WO2010035522A1 - Method and apparatus for etching silicon-containing film - Google Patents

Method and apparatus for etching silicon-containing film Download PDF

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Publication number
WO2010035522A1
WO2010035522A1 PCT/JP2009/054089 JP2009054089W WO2010035522A1 WO 2010035522 A1 WO2010035522 A1 WO 2010035522A1 JP 2009054089 W JP2009054089 W JP 2009054089W WO 2010035522 A1 WO2010035522 A1 WO 2010035522A1
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Prior art keywords
flow rate
gas
etching
fluorine
silicon
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PCT/JP2009/054089
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French (fr)
Japanese (ja)
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俊介 功刀
崇 佐藤
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積水化学工業株式会社
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Priority to KR1020117006861A priority Critical patent/KR101248625B1/en
Priority to CN2009801327624A priority patent/CN102132386B/en
Publication of WO2010035522A1 publication Critical patent/WO2010035522A1/en

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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L21/00—Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof
    • H01L21/02—Manufacture or treatment of semiconductor devices or of parts thereof
    • H01L21/04—Manufacture or treatment of semiconductor devices or of parts thereof the devices having potential barriers, e.g. a PN junction, depletion layer or carrier concentration layer
    • H01L21/18—Manufacture or treatment of semiconductor devices or of parts thereof the devices having potential barriers, e.g. a PN junction, depletion layer or carrier concentration layer the devices having semiconductor bodies comprising elements of Group IV of the Periodic Table or AIIIBV compounds with or without impurities, e.g. doping materials
    • H01L21/30—Treatment of semiconductor bodies using processes or apparatus not provided for in groups H01L21/20 - H01L21/26
    • H01L21/31—Treatment of semiconductor bodies using processes or apparatus not provided for in groups H01L21/20 - H01L21/26 to form insulating layers thereon, e.g. for masking or by using photolithographic techniques; After treatment of these layers; Selection of materials for these layers
    • H01L21/3205—Deposition of non-insulating-, e.g. conductive- or resistive-, layers on insulating layers; After-treatment of these layers
    • H01L21/321—After treatment
    • H01L21/3213—Physical or chemical etching of the layers, e.g. to produce a patterned layer from a pre-deposited extensive layer
    • H01L21/32133—Physical or chemical etching of the layers, e.g. to produce a patterned layer from a pre-deposited extensive layer by chemical means only
    • H01L21/32135—Physical or chemical etching of the layers, e.g. to produce a patterned layer from a pre-deposited extensive layer by chemical means only by vapour etching only
    • H01L21/32136—Physical or chemical etching of the layers, e.g. to produce a patterned layer from a pre-deposited extensive layer by chemical means only by vapour etching only using plasmas
    • H01L21/32137—Physical or chemical etching of the layers, e.g. to produce a patterned layer from a pre-deposited extensive layer by chemical means only by vapour etching only using plasmas of silicon-containing layers
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L21/00—Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof
    • H01L21/02—Manufacture or treatment of semiconductor devices or of parts thereof
    • H01L21/04—Manufacture or treatment of semiconductor devices or of parts thereof the devices having potential barriers, e.g. a PN junction, depletion layer or carrier concentration layer
    • H01L21/18—Manufacture or treatment of semiconductor devices or of parts thereof the devices having potential barriers, e.g. a PN junction, depletion layer or carrier concentration layer the devices having semiconductor bodies comprising elements of Group IV of the Periodic Table or AIIIBV compounds with or without impurities, e.g. doping materials
    • H01L21/30—Treatment of semiconductor bodies using processes or apparatus not provided for in groups H01L21/20 - H01L21/26
    • H01L21/302—Treatment of semiconductor bodies using processes or apparatus not provided for in groups H01L21/20 - H01L21/26 to change their surface-physical characteristics or shape, e.g. etching, polishing, cutting
    • H01L21/306—Chemical or electrical treatment, e.g. electrolytic etching
    • H01L21/3065—Plasma etching; Reactive-ion etching

Definitions

  • the present invention relates to a method and an apparatus for etching a silicon-containing film containing silicon atoms such as amorphous silicon and silicon oxide.
  • the silicon oxide film can be etched by a processing gas containing a fluorine-based reaction gas such as hydrogen fluoride.
  • a silicon film made of substantially silicon atoms such as amorphous silicon can be etched by a processing gas in which a fluorine-based reaction gas such as hydrogen fluoride and an oxidizing reaction gas such as ozone are mixed.
  • Patent Documents 1 and 2 describe that silicon on a wafer surface is oxidized with ozone to form silicon oxide (Equation 1) and then etched using hydrofluoric acid. The hydrofluoric acid is evaporated by a hydrofluoric acid vapor generator and led to the wafer surface.
  • Patent Document 3 HF, and COF 2, etc.
  • Patent Document 5 describes that CF 4 and O 2 are discharged at atmospheric pressure to obtain radicals, which are led from a plasma space to a substrate at a temperature of 20 ° C. or 100 ° C. to etch single crystal silicon.
  • Patent Document 6 describes that humidified CF 4 or dry CF 4 is discharged at atmospheric pressure, and crystalline silicon is etched at a substrate temperature of 90 ° C.
  • Patent Document 7 in etching silicon in a low-pressure chamber, overetching is performed after substituting an etching gas component with a gas species having a high selection ratio with respect to the substrate at the same time or just before the substrate film is exposed. A method is described.
  • etching a silicon-containing film such as amorphous silicon or silicon oxide
  • water added to a fluorine-based raw material for generating a fluorine-based reaction component see Equation 4
  • water generated by an etching reaction see Equation 3
  • the etching reaction is inhibited where there is a condensed water layer. Therefore, the entire silicon-containing film cannot be etched uniformly, and a part of the silicon-containing film tends to remain in spots.
  • the silicon content remaining in the spot shape can be removed by etching, but the base film is etched more than necessary.
  • the composition of the underlying film it can be considered that the greater the moisture content, the greater the selectivity of the silicon-containing film to the underlying film.
  • the present invention provides a method for etching an object to be processed in which a silicon-containing film is laminated on a base film.
  • a treatment gas containing a fluorine-based reaction component is brought into contact with the object to be treated;
  • the flow rate of the processing gas on the object to be processed is changed according to the progress of etching.
  • Water is generated by etching (see Equation 3).
  • the processing gas may contain moisture (see Formula 4).
  • the flow velocity of the processing gas on the object to be processed is increased, the moisture is likely to be scattered from the surface of the object to be processed due to the momentum of the processing gas. Therefore, the amount of moisture adhering to the surface of the workpiece can be adjusted by adjusting the flow rate of the processing gas.
  • the flow rate of the processing gas is preferably set so that the etching rate of the silicon-containing film has a good moisture content. Thereby, processing time can be shortened.
  • the flow rate of the processing gas may be set so that the etching selection ratio of the silicon-containing film to the base film becomes a large amount of moisture. Thereby, the etching of the base film can be suppressed, and the silicon-containing film can be prevented from remaining in the form of spots.
  • silicon-containing material constituting the silicon-containing film examples include silicon (Si), silicon oxide (SiO 2 ), silicon carbide (SiC), silicon oxide carbide (SiOC), and silicon carbonitride (SiCN).
  • Silicon (Si) may be amorphous silicon, polycrystalline silicon, or single crystal silicon.
  • the processing gas further includes an oxidizing reaction component.
  • the oxidizing reaction component is a gas component having an oxidizing action on a substance such as silicon.
  • the silicon-containing film can be oxidized (see Equation 1) and then etched in the same manner as silicon oxide (see Equation 3).
  • Silicon carbide (SiC) and silicon oxide carbide (SiOC) can be converted into silicon (Si) by heating and then etched in the same manner as silicon (see Equations 1 and 3).
  • the oxidizing reaction component include O 3 , O radical, H 2 O 2 , O 2 , NO 2 , N 2 O, and the like, and preferably O 3 .
  • the underlying film only needs to be composed of a component different from the silicon-containing film to be etched, and may be a silicon-containing material.
  • the base film is, for example, silicon oxide (SiO 2 ), silicon nitride (SiN), or the like.
  • the base film is, for example, silicon nitride (SiN).
  • the base film is, for example, silicon nitride (SiN), silicon oxide (SiO 2 ), or the like.
  • Stepwise means that the change in flow rate is discontinuous or stepped.
  • the flow rate may be continuously changed as etching progresses.
  • the flow rate may be changed at least once.
  • the timing for changing is preferably determined in advance by experiments.
  • the flow rate is preferably increased as etching progresses.
  • the flow rate of the processing gas can be made relatively small, and the amount of water adhering to the surface of the object to be processed can be sufficiently increased. Therefore, the etching rate of the silicon-containing film can be increased.
  • the flow rate of the processing gas is relatively increased to dissipate moisture from the surface of the object to be processed and reduce the amount of moisture adhering to the surface of the object to be processed. Can do.
  • the degree of decrease in the etching rate of the base film due to the decrease in the amount of moisture adhering to the surface of the object to be processed is larger than the silicon-containing film made of silicon or the like. . Therefore, the etching selectivity of the silicon-containing film to the base film can be increased. As a result, overetching of the underlying film can be suppressed, and the occurrence of spotted residues in the silicon-containing film can be reliably prevented.
  • the flow rate is preferably increased stepwise as etching progresses. Thereby, control of the flow rate can be facilitated.
  • the flow rate may be gradually increased as etching progresses.
  • the flow rate may be decreased stepwise or continuously in order to increase the selectivity of the silicon-containing film to the underlying film as etching proceeds.
  • the portion of the silicon-containing film to be etched is relatively reduced by relatively reducing the flow rate during a period (hereinafter referred to as “first etching step”) of etching most (or almost the whole) of the silicon-containing film to be etched.
  • first etching step a period of etching a portion remaining after the first etching step
  • second etching step a portion remaining after the first etching step
  • the base film is made of silicon nitride or the like, the selectivity of the silicon-containing film to the base film can be increased. As a result, overetching of the underlying film can be suppressed, and the occurrence of spotted residues in the silicon-containing film can be reliably prevented.
  • “most” means, for example, 50 to 99.9%, preferably 70 to 99.9%, more preferably 80 to 99.9% of the portion to be etched of the silicon-containing film. More preferably 90 to 99.9%.
  • the “substantially the entire” is the upper limit of the “most” and means, for example, 90 to 99.9% of the portion to be etched of the silicon-containing film.
  • the flow rate may be increased stepwise in the first etching step, and the flow rate in the second etching step may be increased from the final step of the first etching step.
  • the flow rate by changing the flow rate of the processing gas. Thereby, the flow velocity can be changed easily and reliably. It is preferable to increase the flow rate of the processing gas as the etching progresses. It is preferable that the flow rate of the processing gas is relatively small in the first etching step, and the flow rate of the processing gas is relatively large in the second etching step.
  • the flow rate of the processing gas it is preferable to change the flow rate of the processing gas by mixing a flow rate adjusting gas with the processing gas or stopping the mixing. Accordingly, the flow rate of the reaction component in the process gas can be kept from changing much regardless of the change in the flow rate of the process gas, and the change in the etching rate of the silicon-containing film can be suppressed. It is preferable to increase the flow rate of the flow rate adjusting gas as the etching progresses. It is preferable that the flow rate of the flow rate adjusting gas is relatively small in the first etching step, and the flow rate of the flow rate adjusting gas is relatively large in the second etching step. By the mixing, the flow rate adjusting gas becomes a component of the processing gas.
  • the fluorine reaction components may be a fluorine-based raw material containing H 2 O and fluorine-based source gas added to be generated through the plasma space of approximately atmospheric pressure.
  • the flow rate adjusting gas may be mixed with the fluorine-based source gas upstream of the plasma space, or the mixing may be stopped, and the flow rate may be adjusted by the flow rate of the flow rate adjusting gas. Since the flow rate of the fluorine-based raw material can be maintained constant, fluctuations in the amount of fluorine-based reaction components generated can be suppressed, and fluctuations in the etching rate of the silicon-containing film can be suppressed.
  • the flow rate adjusting gas may be a dilution gas for the fluorine-based raw material, or may be a gas different from the dilution gas.
  • a flow rate adjusting gas is mixed with the processing gas downstream from the plasma space, or mixing is stopped, and the flow rate is adjusted by the flow rate of the flow rate adjusting gas.
  • the flow rate ratio and flow rate of each component of the gas introduced into the plasma space can be maintained constant regardless of the change in the flow velocity. Thereby, the discharge in the plasma space can be stabilized. Therefore, fluctuations in the etching rate of the silicon-containing film can be more reliably suppressed.
  • the flow rate of the flow rate adjusting gas in the first etching step may be zero.
  • the present invention provides an apparatus for etching an object to be processed in which a silicon-containing film is laminated on a base film.
  • a processing gas supply system for supplying a processing gas containing a fluorine-based reaction component to the object to be processed;
  • a flow rate adjusting means for changing the flow rate of the process gas on the workpiece according to the progress of etching;
  • the amount of water adhesion on the surface of the workpiece can be adjusted by adjusting the flow rate.
  • the etching rate of the silicon-containing film can be adjusted to be good at a stage that does not affect the base film. Therefore, the processing time can be shortened.
  • the silicon-containing film can be adjusted to have a good selectivity with respect to the base film. Therefore, etching of the base film can be suppressed, and the occurrence of spotted residues in the silicon-containing film can be reliably prevented.
  • the flow rate adjusting means preferably changes the flow rate stepwise as etching progresses. Thereby, the control of the flow rate adjusting means can be facilitated.
  • the flow rate adjusting means may continuously change the flow rate as etching progresses.
  • the flow rate adjusting means increase the flow rate as etching progresses.
  • the flow rate of the processing gas is relatively reduced, the amount of moisture attached to the surface of the object to be processed is increased, and the etching rate of the silicon-containing film can be increased. Therefore, the processing time can be reliably shortened.
  • the flow rate of the processing gas is relatively increased to dissipate moisture from the surface of the object to be processed and reduce the amount of moisture adhering to the surface of the object to be processed. Can do.
  • the base film is made of silicon nitride or the like, the selectivity of the silicon-containing film to the base film can be increased. As a result, overetching of the underlying film can be suppressed, and the occurrence of spotted residues in the silicon-containing film can be reliably prevented.
  • the flow rate adjusting means increase the flow rate stepwise as etching progresses. Thereby, the control of the flow rate adjusting means can be facilitated.
  • the flow rate adjusting means may gradually increase the flow rate continuously as etching progresses.
  • the flow rate adjusting means may decrease the flow rate stepwise or continuously in order to increase the selectivity of the silicon-containing film to the underlying film as etching proceeds.
  • the flow rate adjusting means reduces the flow rate relatively until most of the portion to be etched of the silicon-containing film is etched, and relatively increases the flow rate when etching the remaining silicon-containing film. It is preferable. Thus, when most of the portion to be etched of the silicon-containing film is etched, the amount of moisture attached to the surface of the object to be processed can be increased to reliably increase the etching rate. Therefore, the processing time can be reliably shortened. Thereafter, when the remaining silicon-containing film is etched, moisture is scattered from the surface of the object to be processed, and the amount of moisture adhering to the surface of the object to be processed can be reduced.
  • the base film is made of silicon nitride or the like, the selectivity of the silicon-containing film to the base film can be increased. As a result, overetching of the underlying film can be suppressed, and the occurrence of spotted residues in the silicon-containing film can be reliably prevented.
  • the flow rate adjusting means is a flow rate adjusting means for adjusting the flow rate of the processing gas.
  • the flow rate adjusting means can have a simple structure, and the flow rate can be reliably changed.
  • the flow rate adjusting means increases the flow rate of the processing gas as etching progresses.
  • the flow rate adjusting means may reduce the flow rate of the processing gas as etching progresses.
  • the processing gas supply system introduces into the plasma space a plasma generation unit that forms a plasma space near atmospheric pressure, and a fluorine-based source gas that includes a fluorine-based material that serves as the fluorine-based reaction component and to which H 2 O is added. And a raw material supply line.
  • the flow rate adjusting means may mix the flow rate adjusting gas into the raw material supply line or stop mixing, and adjust the flow rate according to the flow rate of the flow rate adjusting gas.
  • the flow rate of the fluorine-based raw material can be kept constant, so that fluctuations in the amount of fluorine-based reaction components generated can be suppressed, and fluctuations in the etching rate of the silicon-containing film can be suppressed.
  • the flow rate adjusting gas constitutes one component of the processing gas.
  • the flow rate adjusting unit mix or stop mixing the flow rate adjusting gas into the processing gas supply system downstream of the plasma space, and adjust the flow rate according to the flow rate of the flow rate adjusting gas. Accordingly, the flow rate ratio and flow rate of each component of the gas introduced into the plasma space can be maintained constant regardless of the change in the flow velocity. Therefore, the discharge in the plasma space can be stabilized. Therefore, fluctuations in the etching rate of the silicon-containing film can be more reliably suppressed.
  • the present invention provides an apparatus for etching an object to be processed in which a silicon-containing film is laminated on a base film.
  • a plurality of processing gas supply systems for blowing out a processing gas containing a fluorine-based reaction component;
  • a switching means for selectively switching a processing gas supply system in which a processing gas is sprayed onto the object to be processed according to the progress of etching; And having different flow rates on the object to be processed when the process gases from at least two of the plurality of process gas supply systems are sprayed on the object to be processed. .
  • the flow rate of the processing gas sprayed on the workpiece can be adjusted by selecting the processing gas supply system.
  • the amount of moisture adhering to the surface of the workpiece can be adjusted by the difference in flow rate.
  • the etching rate of the silicon-containing film can be adjusted to be good at a stage that does not affect the base film. Therefore, the processing time can be shortened.
  • the silicon-containing film can be adjusted to have a good selectivity with respect to the base film. Therefore, etching of the base film can be suppressed, and the occurrence of spotted residues in the silicon-containing film can be reliably prevented.
  • the switching unit selects a processing gas supply system having a relatively high flow rate as etching progresses.
  • the treatment gas from the supply system with a low flow rate is blown onto the object to be processed, so that the amount of moisture adhering to the surface of the object to be processed can be increased, and the etching rate of the silicon-containing film can be ensured.
  • the processing gas from the supply system with a high flow rate is blown onto the object to be processed, so that the water is scattered from the surface of the object to be processed and the water adheres to the surface of the object to be processed.
  • the amount can be reduced. Therefore, when the base film is made of silicon nitride or the like, the selectivity of the silicon-containing film to the base film can be increased. As a result, overetching of the underlying film can be suppressed, and the occurrence of spotted residues in the silicon-containing film can be reliably prevented.
  • the switching means selects a processing gas supply system having a relatively low flow rate until most of the portion to be etched of the silicon-containing film is etched, and when the remaining silicon-containing film is etched, the flow rate is It is preferable to select a relatively large process gas supply system.
  • a processing gas supply system having a relatively low flow rate until most of the portion to be etched of the silicon-containing film is etched, and when the remaining silicon-containing film is etched, the flow rate is It is preferable to select a relatively large process gas supply system.
  • the base film is made of silicon nitride or the like, the selection ratio of the silicon-containing film to the base film can be increased. As a result, over-etching of the base film can be suppressed, and the occurrence of spotted residues in the silicon-containing film can be reliably prevented.
  • the flow rates of the processing gases of at least two processing gas supply systems among the plurality of processing gas supply systems are different from each other. Thereby, the flow rate of the processing gas on the workpiece can be changed by switching the processing gas supply system and changing the flow rate of the processing gas sprayed on the workpiece.
  • the switching unit selects a processing gas supply system in which the flow rate of the processing gas is relatively large as etching progresses.
  • the switching means may select a processing gas supply system in which the flow rate of the processing gas is relatively small as etching progresses.
  • Each processing gas supply system introduces into the plasma space a plasma generation unit that forms a plasma space near atmospheric pressure, and a fluorine-based source gas that includes a fluorine-based material that serves as the fluorine-based reaction component and to which H 2 O is added.
  • a flow rate adjusting gas supply unit that joins the flow rate adjusting gas to the source supply line of at least one processing gas supply system.
  • Each processing gas supply system introduces into the plasma space a plasma generation unit that forms a plasma space near atmospheric pressure, and a fluorine-based source gas that includes a fluorine-based material that serves as the fluorine-based reaction component and to which H 2 O is added.
  • a flow rate adjusting gas supply unit that joins the flow rate adjusting gas to the processing gas supply system downstream of the plasma space of the at least one processing gas supply system. .
  • the processing gas supply system to which the flow rate adjusting gas supply unit is connected it is possible to easily increase the flow rate of the processing gas from the processing gas supply system to which the flow rate adjusting gas supply unit is not connected, and as a result The gas flow rate at can be easily increased.
  • the flow rate adjusting gas is not introduced into the plasma space, the discharge can be stabilized, and the reaction components can be generated stably. it can.
  • Examples of the fluorine-based raw material include perfluorocarbon (PFC), hydrofluorocarbon (HFC), SF 6 , NF 3 , and XeF 2 .
  • Examples of the PFC include CF 4 , C 2 F 6 , C 3 F 6 , C 3 F 8 and the like.
  • Examples of the HFC include CHF 3 , C 2 H 2 F 2 , and CH 3 F.
  • An OH-containing compound may be used in place of H 2 O.
  • Examples of the OH group-containing compound include hydrogen peroxide water and alcohol.
  • Examples of the dilution gas for the fluorine-based material include N 2 and the like in addition to rare gases such as Ar and He.
  • Examples of the fluorine-based reaction component include HF, COF 2 and the like.
  • a dilution gas may be used as the flow rate adjusting gas, and the flow rate of the dilution gas may be changed.
  • the processing gas supply system supplies a processing gas containing a fluorine-based reaction component and an oxidizing reaction component to the object to be processed. It is preferable to do. Thereby, the silicon-containing material can be oxidized with an oxidizing reaction component (Equation 1), and then etched with a fluorine-based reaction component (Equation 3).
  • the silicon-containing material is silicon carbide, silicon oxide carbide, or the like, it is preferable to further include a heating unit.
  • silicon carbide, silicon oxide silicon carbide, or the like can be siliconized, and then etched in the same manner as when the silicon-containing material is silicon.
  • the oxygen-based source gas in which the source supply line becomes the fluorine-based source gas and an oxidizing reaction component (O 3 , O radical, etc.) It is preferable to introduce at least a fluorine source gas into the plasma space.
  • the flow rate adjusting gas is preferably an inert gas or an oxidizing reaction gas.
  • the inert gas include nitrogen (N 2 ) in addition to noble gases such as Ar and He. From the viewpoint of reducing the running cost, it is preferable to use nitrogen as the inert gas serving as the flow rate adjusting gas.
  • the oxidizing reaction gas contains the oxidizing reaction component (ozone (O 3 ), hydrogen peroxide (H 2 O 2 ), oxygen (O 2 ), etc.), and preferably contains ozone (O 3 ).
  • the oxidizing reaction gas may contain a plurality of kinds of oxidizing reaction components, or may contain raw material components of the oxidizing reaction components.
  • the oxidizing reaction gas may be a mixed gas of ozone (O 3 ) and oxygen (O 2 ).
  • the oxidizing reaction gas may contain an inert gas such as nitrogen or Ar.
  • a processing gas is Contains an oxidizing reactive gas for causing an oxidation reaction.
  • the flow rate of the oxidizing gas may be changed to change the flow rate of the processing gas, and thus the flow rate may be changed.
  • the oxidizing reaction gas can be used as a flow rate adjusting gas. Therefore, it is not necessary to separately prepare a gas dedicated for adjusting the flow rate, and the type of gas used can be reduced.
  • the flow rate of the fluorine-based source gas or the fluorine-based reaction gas can be maintained constant regardless of the flow rate change of the entire processing gas. Therefore, fluctuations in the etching rate of the silicon-containing film can be suppressed. Even when no oxidizing reaction component is required to etch the silicon-containing film, an oxidizing reaction gas may be used as the flow rate adjusting gas.
  • the process gas supply system supplies a fluorine-based reaction gas containing the fluorine-based reaction component to the object to be processed, and a fluorine-based reaction gas supply system that supplies the reaction object.
  • the flow rate adjusting means may adjust the flow rate of the supply gas of the oxidizing reaction gas supply system.
  • the supply flow rate of the oxidizing reaction gas can be changed according to the progress of etching, and the supply flow rate of the entire process gas can be changed.
  • the flow rate of the processing gas can be adjusted.
  • the oxidizing reaction gas can be used for etching (oxidation reaction) of the silicon-containing film and also as a flow rate adjusting gas. Therefore, a gas dedicated to the flow rate adjustment is not necessary, and the required gas species can be reduced.
  • the flow rate of the fluorine-based reactive gas by the fluorine-based reactive gas supply system is maintained constant regardless of the flow rate control of the oxidizing reactive gas. be able to. Thereby, fluctuations in the etching rate of the silicon-containing film can be suppressed.
  • the oxidizing reaction gas can be generated by a gas excitation device such as a plasma generation unit or an ozonizer using an oxygen-based source gas as a raw material.
  • a gas excitation device such as a plasma generation unit or an ozonizer using an oxygen-based source gas as a raw material.
  • oxygen gas (O 2 ) as an oxygen-based source gas into the plasma generation unit to generate plasma
  • an oxidizing reaction gas containing an oxidizing reaction component such as oxygen radicals
  • oxygen gas (O 2 ) as an oxygen-based source gas into the ozonizer
  • an oxidizing reaction gas composed of an ozone-containing gas can be generated.
  • the oxidizing reaction gas is used as a flow rate adjusting gas, the supply flow rate of the oxygen-based source gas to the plasma discharge unit or the ozonizer may be adjusted. As a result, the flow rate of the oxidizing reaction gas can be adjusted, and consequently the flow rate of the processing gas can be adjusted.
  • the oxygen-based source gas is a gas that is a raw material for the oxidizing reaction gas.
  • examples of the oxygen-based source gas include O 2 , NO, NO 2 , N 2 O and the like, preferably O 2 . These oxygen-based source gases themselves have some oxidizing action and function as oxidizing reaction gases.
  • the raw material supply line may be configured to mix and introduce the fluorine-based source gas and the oxygen-based source gas into the plasma space.
  • the oxidizing reaction component may be obtained by converting the oxygen-based source gas into plasma, excitation activation, or ozonization on a line different from the source supply line.
  • the fluorine-based reaction component from the raw material supply line and the oxidizing reaction component from the other line may be mixed and supplied to the object to be processed, or supplied to the object to be processed from separate outlets. You may decide to do it.
  • the oxidizing reaction gas is preferably generated in the separate line.
  • the production efficiency of the fluorine-based reaction gas can be reliably maintained constant regardless of the flow rate change of the oxidizing reaction gas.
  • the etching rate of the silicon-containing film can be stabilized.
  • the processing gas supply system may include a container such as a cylinder storing the oxidizing reaction gas.
  • the oxidizing reaction gas may be supplied as it is from the container to the object to be processed. Thereby, the plasma discharge part and the ozonizer for generating the oxidizing reaction gas can be omitted.
  • the oxidizing reaction gas is used as the flow rate adjusting gas, the supply flow rate of the oxidizing reaction gas from the container may be adjusted.
  • the oxidizing reaction gas supply path from the vessel is preferably joined to the fluorine-based reaction gas supply path downstream from the plasma generation unit for generating the fluorine-based reaction gas.
  • the vicinity of atmospheric pressure refers to a range of 1.013 ⁇ 10 4 to 50.663 ⁇ 10 4 Pa, and 1.333 ⁇ 10 4 to 10.664 considering the ease of pressure adjustment and the simplification of the apparatus configuration.
  • ⁇ 10 4 Pa is preferable, and 9.331 ⁇ 10 4 to 10.397 ⁇ 10 4 Pa is more preferable.
  • the silicon-containing film can be etched without residue and at a high rate, and etching of the base film can be suppressed.
  • FIG. 1 is an explanatory diagram showing a schematic configuration of the first embodiment of the present invention.
  • 2A is a cross-sectional view of the workpiece before etching
  • FIG. 2B is a plan view of the workpiece at the end of the first etching step
  • FIG. It is sectional drawing of FIG.2 (b)
  • FIG.2 (d) is a top view of the to-be-processed object at the time of completion
  • FIG. 3 is an explanatory diagram showing a schematic configuration of the second embodiment of the present invention.
  • FIG. 4 is an explanatory diagram showing a schematic configuration of the third embodiment of the present invention.
  • FIG. 5 is an explanatory diagram showing a schematic configuration of the fourth embodiment of the present invention.
  • FIG. 1 is an explanatory diagram showing a schematic configuration of the first embodiment of the present invention.
  • 2A is a cross-sectional view of the workpiece before etching
  • FIG. 2B is a plan
  • FIG. 6 is an explanatory diagram showing a schematic configuration of the fifth embodiment of the present invention.
  • FIG. 7 is an explanatory diagram showing a schematic configuration of the sixth embodiment of the present invention.
  • FIG. 8 is an explanatory diagram showing a schematic configuration of the seventh embodiment of the present invention.
  • FIG. 9 is an explanatory diagram showing a schematic configuration of the eighth embodiment of the present invention.
  • FIG. 10 is a graph showing the results of Example 2.
  • FIG. 11 is a graph showing the results of Example 3.
  • FIG. 2A shows an example of the workpiece 90 before etching.
  • the object 90 to be processed includes, for example, glass for flat panel display as a substrate 91, a base film 92 is formed on the glass substrate 91, and a silicon-containing film 93 to be etched is laminated on the base film 92.
  • the base film 92 is made of, for example, silicon nitride (SiNx).
  • the silicon-containing film 93 to be etched is made of, for example, amorphous silicon (a-Si).
  • a portion of the silicon-containing film 93 of the workpiece 90 that should not be etched is covered with a mask such as a resist.
  • a portion of the silicon-containing film 93 that is not masked becomes a portion to be etched.
  • FIG. 1 shows an example of an etching apparatus 1 used for etching the silicon-containing film 93.
  • the etching apparatus 1 includes a processing gas supply system 10 and a support unit 20.
  • the workpiece 90 is supported by the support unit 20.
  • the support part 20 is composed of a stage, for example.
  • a heating unit 21 is provided inside the support unit 20. The workpiece 90 can be heated by the heating unit 21.
  • the processing gas supply system 10 includes a raw material supply line 30 and a plasma generation unit 40.
  • a fluorine-based material supply unit 31 is provided at the upstream end of the material supply line 30.
  • the fluorine-based material supply unit 31 sends a fluorine-based material gas to the material supply line 30.
  • the fluorine-based raw material include CF 4 , CHF 3 , C 2 F 6 , C 3 F 8 , SF 6 , NF 3 , and XeF 2 .
  • CF 4 is used as the fluorine-based material.
  • the fluorine-based raw material may be diluted with a diluent gas such as Ar, He, N 2 or the like, or may not be diluted.
  • CF 4 diluted with Ar is used as the fluorine-based source gas.
  • An addition unit 32 is connected to the raw material supply line 30.
  • the addition unit 32 is configured by a humidifier that stores liquid water (H 2 O), vaporizes the liquid water, and adds it to the fluorine-based source gas (CF 4 + Ar) in the source supply line 30. ing.
  • a part of the fluorine-based raw material gas flowing through the raw material supply line 30 is diverted to the addition unit 32, and this diverted gas is brought into contact with the liquid surface of the addition unit 32 to vaporize water into the diversion gas.
  • the diverted gas may be bubbled in the water of the addition unit 32 to vaporize the water. Water may be vaporized by heating with a heater and supplied to the raw material supply line 30.
  • An oxygen-based raw material supply unit 34 is connected downstream from the addition unit 32 of the raw material supply line 30.
  • the raw material supply unit 34 supplies an oxygen-based raw material gas to the raw material supply line 30.
  • the fluorine-based source gas and the oxygen-based source gas are mixed in the source supply line 30.
  • the oxygen-based raw material include O 2 , NO, NO 2 , and N 2 O.
  • O 2 gas is used as the oxygen-based source gas.
  • the connection point of the oxygen-based material supply unit 34 to the material supply line 30 may be upstream of the addition unit 32.
  • the raw material supply line 30 is connected to a flow rate adjusting gas supply unit 60 (flow rate adjusting means).
  • the connection point of the flow rate adjusting gas supply unit 60 to the raw material supply line 30 is on the downstream side of the water addition unit 32 and on the downstream side of the connection unit with the oxygen-based raw material supply unit 34, but is not limited thereto. It may be upstream from the oxygen-based raw material supply unit 34, or may be upstream from the water addition unit 32.
  • the flow rate adjusting gas supply unit 60 stores a flow rate adjusting gas.
  • the flow rate adjusting gas is preferably an inert gas.
  • the inert gas include N 2 in addition to noble gases such as Ar and He.
  • N 2 is used as the flow rate adjusting gas.
  • the flow rate adjusting gas supply unit 60 can take two states: a mixing mode in which the flow rate adjusting gas is mixed in the raw material supply line 30 and a stop mode in which mixing is stopped. Although detailed illustration is omitted, the flow rate adjusting gas supply unit 60 is provided with an on-off valve and a flow rate control valve. With these valves, either the mixing mode or the stop mode is selected, and the flow rate of the flow rate adjusting gas (N 2 ) in the mixing mode is adjusted.
  • the downstream end of the raw material supply line 30 extends to the plasma generation unit 40.
  • the plasma generation unit 40 has a pair of electrodes 41 and 41 facing each other.
  • a solid dielectric layer (not shown) is provided on the facing surface of at least one of the electrodes 41.
  • One of these electrodes 41, 41 is connected to a power source 42, and the other is electrically grounded.
  • a raw material supply line 30 is connected to the upstream end of the plasma space 43.
  • an ejection portion 59 made of a nozzle is provided at the downstream end of the plasma space 43.
  • the ejection part 59 faces the workpiece 90 on the support part 20.
  • the ejection part 59 may be relatively moved (scanned) with respect to the support part 20 so as to reciprocate between both ends of the support part 20.
  • the bottom surface of the ejection portion 59 has a certain area, and defines a gas path between the workpiece 90 and the workpiece.
  • the processing gas ejected from the opening of the ejection part 59 flows in a direction away from the opening of the ejection part 59 along the surface of the workpiece 90 in the gas path.
  • the etching process is divided into a first etching process from the initial stage to the middle stage (before reaching the final stage) of etching and a second etching process performed at the final stage of etching.
  • a fluorine-based source gas (CF 4 + Ar) is sent from the fluorine-based source supply unit 31 to the source supply line 30.
  • Water (H 2 O) is added to the fluorine-based source gas by the addition unit 32.
  • the addition amount of water is adjusted by the addition unit 32.
  • the amount of water added is increased as much as possible without causing condensation.
  • the fluorine source gas contains water having a dew point temperature of 10 to 50 ° C.
  • the dew point temperature of the fluorine-based source gas is preferably lower than the ambient temperature or the temperature of the workpiece 90. Thereby, dew condensation can be prevented in the piping constituting the raw material supply line 30 and on the surface of the workpiece 90.
  • the dew point of the fluorine-based source gas is 15 to 20 ° C.
  • the oxygen-based material gas (O 2 ) from the oxygen-based material supply unit 34 is mixed with the fluorine-based material gas (CF 4 + Ar + H 2 O) after adding water to generate a mixed material gas.
  • volume ratio of water is sufficiently small with respect to the fluorine-based source gas and the oxygen-based source gas, the volume ratio between the fluorine-based source gas and the oxygen-based source gas before adding water and the fluorine after adding water
  • the volume ratio of the system material gas and the oxygen system material gas is almost the same.
  • the flow rate adjusting gas supply unit 60 is set to a stop mode, and mixing of the flow rate adjusting gas (N 2 ) into the raw material supply line 30 is stopped.
  • the mixed raw material gas (CF 4 + Ar + O 2 + H 2 O) is introduced as it is into the inter-electrode space 43 from the downstream end of the raw material supply line 30 without being mixed with the flow rate adjusting gas (N 2 ).
  • the first processing gas is a recipe that can etch the silicon 93 at a high rate.
  • the fluorine-based reaction component include HF, COF 2 and the like. These fluorine-based reaction components are mainly produced by the decomposition of CF 4 and H 2 O.
  • the oxidizing reaction component include O 3 and O radicals. These oxidizing reaction components are mainly produced using O 2 as a raw material.
  • the first processing gas is ejected from the plasma generation unit 40 and sprayed onto the workpiece 90 on the support unit 20.
  • the first processing gas flows on the surface of the workpiece 90.
  • the gas flow rate on the surface of the workpiece 90 is smaller than the second etching step described later.
  • the oxidizing reaction component in the first processing gas comes into contact with the silicon-containing film 93 made of amorphous silicon, and an oxidation reaction of silicon occurs to generate silicon oxide (Formula 1).
  • a fluorine-based reaction component comes into contact with this silicon oxide (formula 3), and volatile SiF 4 is generated.
  • the silicon-containing film 93 is etched at a good etching rate.
  • the first processing gas also contains a component of the mixed raw material gas that has not been decomposed in the plasma space 43, and thus also contains water.
  • a part of this water reacts with the fluorine-based reaction component COF 2 to generate HF (Equation 2) and contributes to the etching of silicon.
  • a part of the remaining water adheres to the surface of the workpiece 90 and condenses.
  • water is generated by the etching reaction (formula 3) by HF, and a part of this water adheres to the surface of the workpiece 90 and condenses.
  • a condensed layer of water is formed on the surface of the workpiece 90.
  • the flow rate of the first processing gas on the workpiece 90 is large enough to prevent the moisture on the surface of the workpiece 90 from scattering too much. Therefore, the condensed layer can be made to an appropriate thickness, and the silicon etching rate can be made sufficiently high.
  • the water condensate layer may become thicker than necessary at the surface of the workpiece 90.
  • the etching reaction is hindered where the condensed layer is thick. Therefore, as shown in FIGS. 2B and 2C, the surface of the workpiece 90 just before the etching reaches the final stage, the portion where the base film 92 is exposed, and the silicon-containing film 93 to be etched. Can still be left.
  • the remaining silicon-containing film 93 is referred to as a remaining film 93a.
  • the remaining film 93a has a spotted shape (a mottled shape).
  • the flow rate adjusting gas supply unit 60 is set to the mixed mode.
  • Other operations and processing conditions are preferably the same as those in the first etching step. Therefore, the flow rate adjusting gas (N 2 ) is mixed from the flow rate adjusting gas supply unit 60 to the mixed source gas (CF 4 + Ar + O 2 + H 2 O) having the same component and the same flow rate as the first etching step. Thereby, the flow volume of source gas increases.
  • the mixed raw material gas (CF 4 + Ar + O 2 + H 2 O + N 2 ) is introduced into the plasma space 43 to be converted into plasma.
  • a processing gas containing a fluorine-based reaction component such as HF or COF 2 and an oxidizing reaction component such as O 3 or O radical is generated.
  • the processing gas in the second etching step is appropriately referred to as “second processing gas”.
  • the flow rate of the second processing gas is larger than the flow rate of the first processing gas in the first etching step by the amount of the mixed flow rate adjusting gas (N 2 ).
  • the amounts of the fluorine-based reaction component (such as HF) and the oxidizing reaction component (such as O 3 ) in the second processing gas are substantially equal to those in the first etching step.
  • the second processing gas is ejected from the ejection part 59 and sprayed onto the workpiece 90.
  • the opening degree of the ejection part 59 is constant, so that the blowing speed of the second processing gas from the ejection part 59 is larger than the blowing speed of the first processing gas in the first etching step.
  • the second processing gas flows on the surface of the workpiece 90. While the gas flow rate has increased, the distance (working distance) between the ejection portion 59 and the object to be processed 90 is constant, so the flow rate of the second processing gas on the surface of the object to be processed 90 is It becomes larger than the flow velocity of the first processing gas in one etching process.
  • the amount of moisture adhering to the surface of the workpiece 90 is smaller than that in the first etching step, and the thickness of the condensed layer is smaller than that in the first etching step.
  • the etching rate of the underlying silicon nitride film 92 decreases.
  • the degree of decrease in the etching rate of silicon nitride is greater than the degree of decrease in the etching rate associated with the decrease in the silicon condensation layer. Therefore, the selection ratio of the etching target film 93 to the base film 92 can be increased.
  • the amount of the fluorine-based reaction component (HF or the like) and the oxidizing reaction component (O 3 or the like) in the second processing gas is substantially equal to that in the first etching step, it is possible to suppress a decrease in the etching rate of silicon.
  • the spot-like residual film 93a can be selectively etched and removed at a good etching rate, and the overetching amount d of the base film 92 can be reduced.
  • Switching from the first etching step to the second etching step can be easily performed only by switching the flow rate adjusting gas supply unit 60 from the stop mode to the mixing mode.
  • the addition unit 32 changes the water addition rate. Is also responsive.
  • Second Embodiment As shown in FIG. 3, the second embodiment is different from the first embodiment (FIG. 1) in the mixing location of the flow rate adjusting gas into the processing gas supply system 10.
  • the flow rate adjusting gas supply unit 60 is connected not to the raw material supply line 30 upstream of the plasma generation unit 40 but to the ejection line 50 downstream of the plasma generation unit 40.
  • the ejection line 50 extends from the plasma space 43.
  • a jet part 59 is provided at the downstream end of the jet line 50.
  • a flow rate adjusting gas supply unit 60 is connected to an intermediate portion of the ejection line 50.
  • the flow rate adjusting gas supply unit 60 is in a stop mode in the first etching step. Therefore, the operation of the first etching process is the same as that of the first embodiment.
  • the flow rate adjusting gas supply unit 60 is in a mixed mode.
  • a mixed raw material gas (CF 4 + Ar + O 2 + H 2 O) having the same component and the same flow rate as the first etching step is generated and introduced into the plasma generation unit 40.
  • the flow rate adjusting gas is not mixed with the mixed raw material gas before being introduced into the plasma generating unit 40. Therefore, even when the first etching process is switched to the second etching process, the gas state in the plasma space 43 does not change, and the discharge can be stabilized.
  • a processing gas containing a fluorine-based reaction component (HF or the like) and an oxidizing reaction component (O 3 or the like) is obtained.
  • the amount of these reaction components generated can be the same as in the first etching step.
  • This processing gas is led out to the ejection line 50.
  • the processing gas is mixed with a flow rate adjusting gas (N 2 ) from the supply unit 60.
  • N 2 flow rate adjusting gas
  • the processing gas supply system 10 of the third embodiment generates a fluorine-based reaction component and an oxidizing reaction component separately.
  • the processing gas supply system 10 has a fluorine-based reaction gas supply system 33 and an oxidizing reaction gas supply system 35 separately.
  • the fluorine-based reactive gas supply system 33 includes a raw material supply line 30, a plasma generation unit 40, and a fluorine-based ejection path 51.
  • the raw material supply line 30 is the same as that of the second embodiment (FIG. 3) except that the oxygen-based raw material supply unit 34 is not connected.
  • a flow rate adjusting gas supply unit 60 is connected to the fluorine-based jet passage 51.
  • the material supply line 30 introduces only the fluorine-based material gas (CF 4 + Ar + H 2 O) into the plasma generation unit 40.
  • the oxygen-based source gas is not introduced into the plasma generation unit 40.
  • a fluorine-based ejection path 51 extends from the downstream end of the plasma space 43 of the plasma generation unit 40.
  • the oxidizing reaction gas supply system 35 includes an oxygen-based material supply unit 34, a plasma generation unit 44 different from the plasma generation unit 40, and an oxygen-based ejection path 52.
  • the plasma generation unit 44 has a pair of electrodes 45 and 45 facing each other.
  • a solid dielectric layer (not shown) is provided on the opposing surface of at least one of the electrodes 45.
  • One of these electrodes 45, 45 is connected to a power source 46, and the other is electrically grounded.
  • An oxygen-based material supply unit 34 is connected to the upstream end of the plasma space 47.
  • An oxygen-based ejection path 52 extends from the downstream end of the plasma space 47 of the plasma generation unit 44.
  • the ejection path 51 of the fluorine-based reaction gas supply system 33 and the ejection path 52 of the oxidizing reaction gas supply system 35 are joined together.
  • the common jet part 53 is continued to this merge part.
  • the common ejection part 53 faces the workpiece 90 on the support part 20.
  • the common ejection part 53 may be moved relative to the support part 20 so as to reciprocate between both ends of the support part 20.
  • the fluorine-based source gas (CF 4 + Ar + H 2 O) is converted into plasma by the plasma generation unit 40, and a fluorine-based reaction gas containing a fluorine-based reaction component (HF or the like). Is generated and led to the ejection path 51.
  • the oxygen-based source gas (O 2 ) from the oxygen-based source supply unit 34 is introduced into the plasma space 47 of the plasma generation unit 44 to be converted into plasma, and the oxidation reaction occurs.
  • An oxidizing reaction gas containing components (such as O 3 ) is generated.
  • This oxidizing reaction gas is led out from the plasma generation unit 44 to the ejection path 52 and mixed with the fluorine-based reaction gas from the ejection path 51.
  • the fluorine-based source gas and the oxygen-based source gas are converted into plasma by separate plasma generation units 40 and 44, the generation amount of the fluorine-based reaction component and the generation amount of the oxidizing reaction component are sufficiently large. can do. Thereby, the etching rate of the silicon-containing film 93 in each of the first and second etching steps can be increased, and the processing time can be further shortened.
  • the flow rate adjusting gas supply unit 60 is in the stop mode in the first etching step, and the flow rate adjusting gas supply unit 60 is in the mixed mode in the second etching step. It is the same. Therefore, in the second etching step, the flow rate adjusting gas (N 2 ) from the supply unit 60 is introduced into the ejection path 51 and mixed with the fluorine-based reaction gas.
  • an ozonizer 48 is used in place of the plasma generation unit 44 as an oxidizing reaction gas generating device in the oxidizing reaction gas supply system 35.
  • Oxygen gas (O 2 ) from the oxygen-based raw material supply unit 34 is introduced into the ozonizer 48 to generate an oxidizing reaction gas containing O 3 , and this oxidizing reaction gas is led out to the ejection path 52. Yes.
  • Other configurations and operations are the same as those of the third embodiment (FIG. 4).
  • the etching apparatus 1 of the fifth embodiment includes a plurality (two) of processing gas supply systems 10.
  • Each processing gas supply system 10 has substantially the same configuration as the processing gas supply system 10 of the first and second embodiments (FIGS. 1 and 3).
  • each component of the first process gas supply system 10 ⁇ / b> A is denoted by the same reference numeral as the corresponding component in the process gas supply system 10 of the above-described embodiment.
  • the constituent elements of the second processing gas supply system 10B are denoted by the same reference numerals as those of the corresponding constituent elements in the processing gas supply system 10 of the above-described embodiment.
  • the first processing gas supply system 10A is different from the processing gas supply system 10 of the first and second embodiments (FIGS. 1 and 3) in that the flow rate adjusting gas supply unit 60 is not connected. . Therefore, the first processing gas that does not contain the flow rate adjusting gas (N 2 ) is constantly ejected from the first processing gas supply system 10A.
  • the component and flow rate of the first processing gas from the supply system 10A are the same as the first processing gas in the first etching step of the first and second embodiments.
  • the second processing gas supply system 10B has the same configuration as the processing gas supply system 10 of the second embodiment (FIG. 3). However, the flow rate adjusting gas supply unit 60B of the second processing gas supply system 10B is always operated in the mixed mode. Therefore, the second processing gas including the flow rate adjusting gas (N 2 ) is constantly ejected from the second processing gas supply system 10B. The component and flow rate of the second processing gas from the supply system 10B are the same as the second processing gas in the second etching process of the first and second embodiments.
  • the ejection flow rate of the first processing gas supply system 10A is relatively small by the amount not mixed with the flow rate adjusting gas, and the ejection flow rate of the second processing gas supply system 10B is relatively large by the mixing amount of the flow rate adjusting gas. .
  • the opening degree of the ejection part 59A of the first processing gas supply system 10A and the opening degree of the ejection part 59A of the second processing gas supply system 10B are equal to each other. Therefore, the blow-off flow rate from the first processing gas supply system 10A is relatively small.
  • the blowing flow rate from the second processing gas supply system 10A is relatively large.
  • the moving means 22 is connected to the support part 20.
  • the moving means 22 includes, for example, a drive unit such as a motor and a slide unit that is advanced and retracted by the drive unit, and the support unit 20 is connected to the slide unit.
  • the moving unit 22 causes the support unit 20 to have a first position (solid line in FIG. 6) facing the first processing gas ejection part 59A and a second position (in FIG. 6) facing the second processing gas ejection part 59A. It is designed to move between the two-dot chain line).
  • the support unit 20 is positioned at the first position by the moving means 22.
  • the first processing gas ejected from the first processing gas supply system 10 ⁇ / b> A contacts the workpiece 90.
  • the flow rate of the first processing gas is relatively low, and the flow rate on the workpiece 90 is relatively small. Therefore, a condensed layer of water having an appropriate thickness is easily formed on the surface of the workpiece 90, and the etching rate of the silicon-containing film 93 can be increased.
  • the support unit 20 When most of the silicon-containing film 93 is etched, the support unit 20 is moved from the first position to the second position by the moving means 22. Thereby, it is possible to shift from the first etching process to the second etching process with little time.
  • the second processing gas ejected from the second processing gas supply system 10 ⁇ / b> B comes into contact with the workpiece 90.
  • the flow rate of the second process gas is higher than the gas flow rate of the first process gas supply system 10A. Therefore, moisture can be scattered from the surface of the object to be processed 90, and formation of a condensed layer of water on the surface of the object to be processed 90 can be suppressed.
  • the moving unit 22 constitutes a switching unit that selectively switches between the processing gas supply systems 10 ⁇ / b> A and 10 ⁇ / b> B through which the processing gas is blown onto the workpiece 90.
  • the moving speed of the support part 20 and the number of the processing gas supply systems 10 used in the first etching step are determined in advance so that the base film 92 is exposed in the first etching step or is left on the base film 92 by experiments.
  • the thickness of the silicon-containing film 93 is determined to be extremely small.
  • the moving means 22 may be connected to the ejection parts 59A, 59B instead of the support part 20, and instead of moving the support part 20 between the first position and the second position, the ejection parts 59A, By moving 59B, the ejection part 59A may be opposed to the support part 20 in the first etching process, and the ejection part 59B may be opposed to the support part 20 in the second etching process.
  • the workpiece 94 is a continuous sheet.
  • the continuous sheet-like workpiece 94 is fed from the feed roll 23 and taken up by the take-up roll 24.
  • a heating unit 21 is provided on the back side of the workpiece 94 between the rolls 23 and 24.
  • the ejection part 59A of the first processing gas supply system 10A is disposed at a position between the rolls 23 and 24 near the feeding roll 23.
  • An ejection portion 59B of the second processing gas supply system 10B is disposed at a position near the take-up roll 24 between the rolls 23 and 24.
  • the workpiece 94 fed out from the feed roll 23 comes into contact with the low-flow first processing gas at a low flow rate from the first processing gas supply system 10A. Thereafter, the second process gas is brought into contact with the second process gas at a high flow rate and high speed from the second process gas supply system 10B. Thereby, it can transfer to a 2nd etching process continuously from a 1st etching process.
  • the feeding roll 23 and the take-up roll 24 function as a workpiece support section that replaces the stage-shaped support section 20.
  • the feed roll 23 and the take-up roll 24 constitute a switching unit that selectively switches between the processing gas supply systems 10A and 10B in which the processing gas is blown to the workpiece 90.
  • the change of the flow rate of the processing gas and thus the flow velocity is not limited to two steps, and may be performed in three or more steps.
  • the gas flow rate and thus the flow rate may be changed over two or more stages.
  • the gas flow rate and thus the flow rate may be changed over two or more stages.
  • FIG. 8 shows an embodiment in which the flow rate of the processing gas, and hence the flow rate, is changed over three stages in the first etching process and the second etching process.
  • the etching apparatus 1 includes three processing gas supply systems 10. When these three process gas supply systems 10 are distinguished from each other, X is added to the reference numerals of the first stage (left side in FIG. 8) of the process gas supply system 10 and its components, and the second stage (center in FIG. 8). ) Is attached to the reference numerals of the processing gas supply system 10 and its constituent elements, and Z is attached to the reference numerals of the third stage (right side in FIG. 8) of the processing gas supply system 10 and its constituent elements.
  • the first-stage and second-stage process gas supply systems 10X and 10Y become the first process gas supply system for executing the first etching process.
  • the processing gas supply system 10Z at the final stage (third stage) becomes the second processing gas supply system for executing the second etching process.
  • the first stage processing gas supply system 10X has the same configuration as the first processing gas supply system 10A of the fifth embodiment (FIG. 6) and the sixth embodiment (FIG. 7). That is, the flow rate adjusting gas supply unit 60 is not connected to the processing gas supply system 10X.
  • the processing gas ejected from the first processing gas supply system 10A does not include the flow rate adjusting gas (N 2 ) and has a small flow rate.
  • the second stage processing gas supply system 10Y has the same configuration as the second processing gas supply system 10B of the fifth and sixth embodiments (FIGS. 6 and 7). It is always operated in mixed mode. However, the mixing flow rate of the flow rate adjusting gas is smaller than the mixing flow rate of the flow rate adjusting gas in the second processing gas supply system 10B.
  • the third stage (final stage) processing gas supply system 10Z has the same configuration as the second processing gas supply system 10B of the fifth and sixth embodiments (FIGS. 6 and 7), and the flow rate adjusting gas.
  • Supply unit 60Y is always operated in the mixed mode.
  • the mixed flow rate of the flow rate adjusting gas is also the same as that of the second processing gas supply system 10B.
  • the mixed flow rate of the flow rate adjusting gas by the third stage flow rate adjusting gas supply unit 60Z is preferably 1 to 4 times the mixed flow rate of the flow rate adjusting gas by the second stage flow rate adjusting gas supply unit 60Y. More preferably, it is 2 to 3 times.
  • the ejection portions 59 of the three processing gas supply systems 10 are arranged in a line at intervals.
  • a roller conveyor 25 is installed below these ejection portions 59.
  • the roller conveyor 25 is extended in the arrangement direction of the ejection parts 59.
  • the workpiece 90 is conveyed by the roller conveyor 25 in the order below the first stage ejection part 59X, below the second stage ejection part 59Y, and below the third stage ejection part 59Z.
  • the roller conveyor 25 constitutes a conveying unit and a supporting unit for the workpiece 90.
  • the roller conveyor 25 comprises the switching means which selectively switches the process gas supply system 10 with which process gas is sprayed on the to-be-processed object 90.
  • FIG. The moving speed of the roller conveyor 25 and the number of processing gas supply systems 10 are determined in advance by experiments.
  • the workpiece 90 comes into contact with the processing gas from the second stage processing gas supply system 10Y and is etched.
  • a flow rate adjusting gas (N 2 ) is mixed with the second stage processing gas. Therefore, the flow rate of the second stage processing gas is larger than that of the first stage, and the gas flow rate on the workpiece 90 is larger than that of the first stage.
  • moisture is scattered from the surface of the workpiece 90, and the thickness of the condensed layer on the surface of the workpiece 90 can be made smaller than in the first stage. Therefore, the selection ratio of the silicon-containing film 93 to the base film 92 can be increased. Therefore, when the concave portion of the uneven surface of the silicon-containing film 93 reaches the interface with the base film 92, the base film 92 can be prevented from being scraped.
  • FIG. 9 shows an eighth embodiment of the present invention.
  • the oxidizing reaction gas is used as a flow rate adjusting gas.
  • the processing gas supply system 10 of the eighth embodiment includes a fluorine-based reaction gas supply system 33 and an oxidizing reaction gas supply system 35 having an ozonizer 48, as in the fourth embodiment (FIG. 5). Including.
  • the fluorine-based reactive gas supply system 33 is not connected to a flow rate adjusting gas supply unit 60 as a flow rate adjusting means.
  • an oxidizing reactive gas flow rate adjusting unit 61 is provided as a flow rate adjusting unit on a line connecting the oxygen-based raw material supplying unit 34 and the ozonizer 48 of the oxidizing reactive gas supply system 35.
  • the flow rate adjusting unit 61 includes a flow rate control valve and a mass flow controller.
  • the flow rate adjusting unit 61 adjusts the flow rate of the oxygen-based source gas (O 2 ) supplied from the oxygen-based source supply unit 34 to the ozonizer 48, and as a result, the oxidizing reaction gas (O 2 + O 3 ) from the ozonizer 48. Adjust the supply gas flow rate.
  • the flow rate adjusting unit 61 may be provided in the ejection path 52 downstream from the ozonizer 48.
  • the first etching process of the eighth embodiment is substantially the same as the first etching process of the third and fourth embodiments.
  • the humidified fluorine-based source gas (CF 4 + Ar + H 2 O) is turned into plasma to generate a fluorine-based reaction gas.
  • oxygen-based source gas (O 2 ) is supplied from the oxygen-based source supply unit 34 of the oxidizing reaction gas supply system 35 to the ozonizer 48, and the oxidizing reaction gas (O 2 + O 3 ) is generated by the ozonizer 48.
  • a processing gas is obtained by mixing these fluorine-based reaction gas and oxidizing reaction gas.
  • This processing gas is ejected from the ejection part 53 and brought into contact with the workpiece 90.
  • the supply flow rate of the oxygen-based source gas (O 2 ) and, therefore, the oxidizing reaction gas (O 2 + O 3 ) is increased by the flow rate adjusting unit 61 compared to the first etching process.
  • the supply flow rate of the fluorine-based reaction gas is preferably the same as that in the first etching step.
  • the selection ratio of the silicon film 93 to the base film 92 can be increased.
  • silicone can be suppressed by setting it as the same flow rate as a 1st etching process.
  • the silicon residual film 93a can be selectively etched and removed at a good etching rate, and the overetching amount d of the base film 92 can be reduced.
  • the oxidizing reaction gas also serves as the flow rate adjusting gas, a gas dedicated to the flow rate adjustment (for example, N 2 ) is unnecessary. Therefore, the required gas species can be reduced.
  • the silicon-containing film 93 to be etched is not limited to amorphous silicon, but may be polysilicon or single crystal silicon.
  • the silicon-containing film 93 to be etched is not limited to silicon, and may be silicon oxide, silicon carbide, silicon oxide carbide, or the like.
  • the processing gas does not need to contain an oxidizing reaction component. Therefore, the oxygen-based raw material supply unit 34 can be omitted.
  • the silicon-containing film 93 to be etched is silicon carbide or silicon oxide carbide, it can be converted into silicon by a heating operation, and then etched in the same manner as in the above embodiment.
  • the base film 92 is not limited to silicon nitride, and may be any component different from the silicon-containing film 93 to be etched.
  • the base film 92 may be silicon oxide.
  • the base film may be, for example, silicon nitride.
  • the base film 92 may be, for example, silicon nitride or silicon oxide.
  • the processing gas flow rate on the workpiece 90 may be reduced in order to increase the selectivity of silicon to the underlying film as etching proceeds.
  • the processing gas flow rate in the second etching step may be smaller than that in the first etching step.
  • the processing gas flow rate may be reduced and then increased.
  • the processing gas flow rate may be increased and then decreased.
  • the process gas flow rate is not limited to being changed stepwise, but may be continuously changed (gradual decrease or increase).
  • the mixing flow rate of the flow rate adjusting gas (N 2 ) may be changed stepwise or continuously.
  • Flow rate adjusting means for changing the flow rate of the processing gas, instead of mixing the flow rate adjusting gas (N 2) to the processing gas supply system 10, or to mix the flow rate adjusting gas (N 2)
  • the flow rate of the fluorine-based source gas (CF 4 + Ar) may be changed
  • the flow rate of the dilution gas (Ar) in the fluorine-based source gas may be changed
  • the oxygen-based source material (O 2 ) The flow rate may be changed.
  • the flow rate adjusting means may adjust the opening degree of the ejection portion 59 instead of adjusting the gas flow rate or in addition to adjusting the gas flow rate. You may adjust the thickness (distance between the ejection part 59 and the to-be-processed object 90) of the gas path defined between the ejection part 59 and the to-be-processed object 90.
  • fluorine-based raw material such as C 2 F 6 , C 3 F 6 , and C 3 F 8 may be used as the fluorine-based raw material.
  • CHF 3 , CH 2 F 2 , and CH 3 HFC (hydrofluorocarbon) such as F may be used, and fluorine-containing compounds other than PFC and HFC such as SF 6 , NF 3 , and XeF 2 may be used.
  • fluorine-containing compounds other than PFC and HFC such as SF 6 , NF 3 , and XeF 2 may be used.
  • As a dilution gas other inert gas such as He, Ne, N 2 may be used instead of Ar.
  • oxygen-based raw material oxygen-containing compounds such as NO, NO 2 , and N 2 O may be used instead of O 2 .
  • an OH group-containing compound may be used instead of water (H 2 O).
  • the OH group-containing compound include hydrogen peroxide water (H 2 O 2 ) and alcohols such as ethanol and methanol.
  • H 2 O 2 hydrogen peroxide water
  • alcohols such as ethanol and methanol.
  • H 2 O 2 the reactivity is high and it is difficult to stably add it to the gas of the fluorine-based reaction component.
  • the carbon component (C) reacts when it is introduced into the plasma, and an organic polymer is produced. Therefore, it is necessary to decompose and remove it. Therefore, H 2 O that can be supplied simply and stably is preferable.
  • the oxidizing reaction component itself such as O 3 is stored in a tank or the like, and the oxidizing reaction component is taken out from the tank to remove fluorine. You may mix with a system reaction component.
  • the fluorine-based reaction gas and the oxidizing reaction gas are not mixed and blown out from different jetting parts toward the object to be processed. Also good.
  • the timing of switching from the first etching process to the second etching process is not limited to the stage where the base film 92 is exposed, and may be set to a stage just before the base film 92 is exposed.
  • two processing gas supply systems 10X may be provided side by side, and four processing gas supply systems 10 may be provided in the entire apparatus 1.
  • This structure is suitable when the thickness of the silicon-containing film 93 is large and the amount that can be etched by one processing gas supply system 10X is less than half the thickness of the silicon-containing film 93. That is, by providing two processing gas supply systems 10X, more than half or most of the silicon-containing film 93 can be etched at a good etching rate. Thereafter, etching is performed by increasing the silicon selection ratio in the processing gas supply system 10Y, and then etching is performed by further increasing the silicon selection ratio in the processing gas supply system 10Z.
  • processing gas supply systems 10X may be arranged in parallel.
  • the flow rate adjusting gas supply unit 60 may also be provided in the first stage process gas supply system 10X.
  • a plurality of embodiments may be combined with each other.
  • the flow rate adjusting gas supply unit 60 of the third to seventh embodiments (FIGS. 4 to 8) may be connected to the raw material supply line 30 as in the first embodiment (FIG. 1).
  • Each of the processing gas supply systems 10 of the fifth to seventh embodiments (FIGS. 6 to 8) is similar to that of the third and fourth embodiments (FIGS. 4 and 5). May be generated by different routes.
  • the plasma generator 44 of the third embodiment (FIG. 4) may be used instead of the ozonizer 48.
  • the first and second embodiments (FIGS.
  • the flow rate adjusting gas supply unit 60 is omitted, and instead, the material supply line of the oxygen-based material supply unit 34 is used.
  • the flow rate adjusting unit 61 may be provided on the connection path to the No. 30, and the oxygen-based source gas and thus the oxidizing reaction component may be substituted for the flow rate adjusting gas. In this case, attention is paid to the influence on the stability of the discharge in the plasma generation unit 40 and the generation efficiency of the fluorine-based reaction gas due to the change in the flow rate of the oxygen-based source gas.
  • the flow rate adjusting gas supply unit 60B of the processing gas supply system 10B is omitted, and instead, an oxygen-based material supply is provided.
  • the flow rate adjusting unit 61 may be provided on the connection path of the unit 34B to the raw material supply line 30B, and the oxygen-based raw material gas, and thus the oxidizing reaction component, may be used as the flow rate adjusting gas. In this case, attention is paid to the influence on the stability of the discharge in the plasma generation unit 40B and the generation efficiency of the fluorine-based reactive gas accompanying the change in the flow rate of the oxygen-based source gas.
  • FIG. 1 In the seventh embodiment (FIG.
  • the flow rate adjusting gas supply units 60Y and 60Z of the processing gas supply systems 10Y and 10Z are omitted, and instead, the oxygen-based material supply unit 34Y. , 34Z may be provided on each connection path to the raw material supply lines 30Y, 30Z, and the oxygen-based raw material gas, and thus the oxidizing reaction component, may be substituted for the flow rate adjusting gas.
  • the processing gas supply systems 10 of the fifth to seventh embodiments FIGS.
  • the etching method and the etching apparatus according to the present invention are designed to remove contaminants including silicon adhering to the surface of an object to be processed, and to remove a roughened portion of a silicon wafer or glass in addition to pattern etching of an object to be processed patterned with a resist or the like. It can also be applied to planarization, roughening of the front or back surface of a silicon wafer or glass.
  • the amorphous silicon film was etched in two stages, a first etching process and a second etching process.
  • the base film was silicon nitride, and a sample in which amorphous silicon was laminated on the base film was used.
  • the first etching process was performed.
  • CF 4 was used as a fluorine-based raw material.
  • Ar was used as a dilution gas.
  • CF 4 was diluted with Ar to obtain a fluorine-based source gas (CF 4 + Ar).
  • the fluorine-based source gas (CF 4 + Ar) was added to the fluorine-based source gas (CF 4 + Ar) with a commercially available water addition device. The amount of water was controlled so that the dew point temperature was 18 ° C. The flow rate adjusting gas supply unit 60 was set to the stop mode.
  • the fluorine-based source gas (CF 4 + Ar + H 2 O) after the addition of water was turned into plasma by the plasma generation unit 40 to obtain a fluorine-based reaction gas.
  • the plasma discharge conditions are as follows. Distance between electrodes: 1mm Voltage between electrodes: 12kV Power frequency: 40 kHz (pulse wave)
  • O 2 gas as an oxygen-based source gas was introduced into the ozonizer 48 to obtain an oxidizing reaction gas (O 2 + O 3 ).
  • the ozone concentration of the oxidizing reaction gas was about 8%.
  • the fluorine-based reaction gas from the plasma generation unit 40 and the oxidizing reaction gas from the plasma generation unit 44 were mixed to obtain a first processing gas.
  • the volume mixing ratio of the fluorine-based reaction gas and the oxidizing reaction gas was 1: 1.
  • the workpiece 90 was placed on the stage 20, and the ejection portion 53 was disposed above the workpiece. While the first processing gas was blown out from the ejection portion 53, the ejection portion 53 was moved (scanned) so as to reciprocate from one end to the other end of the workpiece 90. The moving speed was 4 m / min. The one-way movement in the forward direction or the backward direction was set as one scan, the scan was performed 18 times, and the first etching process was completed. At this time, spot-like amorphous silicon 93a having a thickness of 0.1 to 10 ⁇ m remained on the surface of the workpiece 90 (see FIGS. 2B and 2C). The etching rate of the amorphous silicon film in the first etching step was 10.1 nm / scan, and the selectivity of the amorphous silicon film to the silicon nitride film was about 1.3.
  • a second etching step was performed.
  • the flow rate adjusting gas supply unit 60 was set to the mixed mode.
  • the number of scans of the ejection part 53 was four.
  • Other processing conditions in the second etching step were the same as those in the first etching step.
  • the remaining amorphous silicon 93a could be completely removed by the second etching process.
  • the etching rate of the amorphous silicon film in the second etching process was 8.6 nm / scan, and the selection ratio of the amorphous silicon film to the silicon nitride film was higher than that in the first etching process and was about 2.3. Therefore, it was confirmed that the overetching of the underlying silicon nitride film 92 can be reduced.
  • Example 1 The relationship between the mixing ratio of the flow rate adjusting gas to the processing gas and the selectivity of amorphous silicon to silicon nitride was investigated.
  • the etching apparatus shown in FIG. The raw material components and generation conditions of the processing gas were the same as those in Example 1. Nitrogen (N 2 ) was mixed with this processing gas as a flow rate adjusting gas, and the mixed flow rate of nitrogen was changed.
  • the etching rate of amorphous silicon (a-Si) and silicon nitride (SiNx) was measured, and the selection ratio of amorphous silicon (a-Si) to silicon nitride (SiNx) was calculated.
  • Example 3 does not use N 2 gas as a flow rate adjusting gas.
  • an oxidizing reaction gas composed of an ozone-containing gas (O 2 + O 3 ) was generated by the ozonizer 48 as in Example 1.
  • the flow rate of the oxidizing reaction gas was changed so that the volume mixing ratio of the fluorine-based reaction gas and the oxidizing reaction gas was 2: 1 to 1: 2.
  • the flow rate of the fluorine-based reaction gas was constant.
  • the etching rate of amorphous silicon (a-Si) and silicon nitride (SiNx) was measured, and the selection ratio of amorphous silicon (a-Si) to silicon nitride (SiNx) was calculated.
  • the present invention is applicable, for example, to the manufacture of flat panel displays (FPD) and semiconductor wafers.
  • FPD flat panel displays
  • semiconductor wafers semiconductor wafers

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Abstract

Disclosed are a method and an apparatus for etching a silicon-containing film such as a silicon film or a silicon oxide film at a high rate without leaving residues, while suppressing etching of a base film. A silicon-containing film (93) on a base film (92) is etched by bringing a process gas, which contains a fluorine-based reaction component and an oxidizing reaction component, into contact with an object (90) to be processed. The flow rate of the process gas on the object (90) to be processed is changed by a flow rate-regulating means (60) in accordance with the progress of the etching. Preferably, the gas flow rate is changed by regulating the amount of the process gas flow. More preferably, the amount of the process gas flow is regulated by mixing a flow rate-regulating gas into a process gas supply system (10) or by stopping the mixing.

Description

シリコン含有膜のエッチング方法および装置Method and apparatus for etching silicon-containing film
　本発明は、アモルファスシリコンや酸化シリコン等のシリコン原子を含有するシリコン含有膜をエッチングする方法及び装置に関する。 The present invention relates to a method and an apparatus for etching a silicon-containing film containing silicon atoms such as amorphous silicon and silicon oxide.
　酸化シリコン膜は、フッ化水素などのフッ素系反応ガスを含む処理ガスによってエッチングできる。アモルファスシリコン等ほぼシリコン原子からなるシリコン膜は、フッ化水素などのフッ素系反応ガスとオゾンなどの酸化性反応ガスを混合した処理ガスによってエッチングできる。
　例えば、特許文献１、２には、ウェハ表面のシリコンをオゾンによって酸化させ、酸化シリコンとしたうえで（式１）、フッ酸を用いてエッチングすることが記載されている。フッ酸は、フッ酸蒸気発生器で蒸発させ、これをウェハ表面に導いている。
　特許文献３には、ＣＦ４等のフッ素系ガス中に大気圧近傍放電を起こすことによりＨＦ、ＣＯＦ２等を生成し、更にＣＯＦ２についてはＣＦ４等に混合させておいた水と反応させてＨＦとし（式２）、このようにして得たＨＦによって酸化シリコンをエッチング（式３）することが記載されている。
　Ｓｉ＋２Ｏ３→ＳｉＯ２＋２Ｏ２　　　　　　　　　（式１）
　ＣＯＦ２＋Ｈ２Ｏ→ＣＯ２＋２ＨＦ　　　　　　　　（式２）
　ＳｉＯ２＋４ＨＦ＋Ｈ２Ｏ→ＳｉＦ４＋３Ｈ２Ｏ　　（式３）
　特許文献４には、加湿したＣＦ４から大気圧プラズマ放電によってＨＦを得（式４）、これにＯ３を添加し、酸化シリコンをエッチングすることが記載されている。
　ＣＦ４＋２Ｈ２Ｏ→ ４ＨＦ＋ＣＯ２　　　　　　　（式４）
　特許文献５には、ＣＦ４とＯ２を大気圧放電させてラジカルを得、これをプラズマ空間から温度２０℃又は１００℃の基板に導き、単結晶シリコンをエッチングすることが記載されている。
　特許文献６には、加湿ＣＦ４又は乾燥ＣＦ４を大気圧放電させ、基板温度９０℃で結晶シリコンをエッチングすることが記載されている。
　特許文献７には、低圧チャンバー内でのシリコンのエッチングにおいて、下地膜が露出するのと同時もしくは直前に、エッチングガスの成分を下地に対する選択比が高いガス種に置換した後に、オーバーエッチングをする方法が記載されている。 The silicon oxide film can be etched by a processing gas containing a fluorine-based reaction gas such as hydrogen fluoride. A silicon film made of substantially silicon atoms such as amorphous silicon can be etched by a processing gas in which a fluorine-based reaction gas such as hydrogen fluoride and an oxidizing reaction gas such as ozone are mixed.
For example, Patent Documents 1 and 2 describe that silicon on a wafer surface is oxidized with ozone to form silicon oxide (Equation 1) and then etched using hydrofluoric acid. The hydrofluoric acid is evaporated by a hydrofluoric acid vapor generator and led to the wafer surface.
Patent Document 3, HF, and COF 2, etc. generated by causing a pressure near atmospheric pressure discharge fluoric gas such as CF 4, is reacted with water which had been mixed with CF 4 or the like for further COF 2 It is described that silicon oxide is etched (formula 3) with HF thus obtained (formula 2).
Si + 2O 3 → SiO 2 + 2O 2 (Formula 1)
COF 2 + H 2 O → CO 2 + 2HF (Formula 2)
SiO 2 + 4HF + H 2 O → SiF 4 + 3H 2 O (Formula 3)
Patent Document 4 describes that HF is obtained from humidified CF 4 by atmospheric pressure plasma discharge (formula 4), O 3 is added thereto, and silicon oxide is etched.
CF 4 + 2H 2 O → 4HF + CO 2 (Formula 4)
Patent Document 5 describes that CF 4 and O 2 are discharged at atmospheric pressure to obtain radicals, which are led from a plasma space to a substrate at a temperature of 20 ° C. or 100 ° C. to etch single crystal silicon.
Patent Document 6 describes that humidified CF 4 or dry CF 4 is discharged at atmospheric pressure, and crystalline silicon is etched at a substrate temperature of 90 ° C.
In Patent Document 7, in etching silicon in a low-pressure chamber, overetching is performed after substituting an etching gas component with a gas species having a high selection ratio with respect to the substrate at the same time or just before the substrate film is exposed. A method is described.
先行技術文献Prior art documents
特開２００３－２６４１６０号公報JP 2003-264160 A 特開２００４－５５７５３号公報JP 2004-55753 A 特開２０００－５８５０８号公報JP 2000-58508 A 特開２００２－２７０５７５号公報JP 2002-270575 A 特開平０４－３５８０７６号公報Japanese Patent Laid-Open No. 04-358076 特開２０００－１６４５５９号公報JP 2000-164559 A 特開２００２－３４３７９８号公報JP 2002-343798 A
　アモルファスシリコンや酸化シリコン等のシリコン含有膜のエッチングでは、フッ素系反応成分を生成するためのフッ素系原料に添加する水（式４参照）やエッチング反応によって生成される水（式３参照）が、シリコン含有膜の表面に付着して凝縮する。凝縮した水の層がある箇所ではエッチング反応が阻害される。したがって、シリコン含有膜の全体を均一にエッチングすることができず、シリコン含有膜の一部が斑点状に残りやすい。
　シリコン含有膜の表面に水分が付着する度に乾燥工程を行なって水分を除去することも考えられるが、処理時間が長くなり、実用的ではない。
　オーバーエッチングを十分に行なうと、斑点状に残ったシリコン含有をエッチングして除去することができるが、下地膜が必要以上にエッチングされてしまう。
　下地膜の成分等によっては水分が多いほうがシリコン含有膜の下地膜に対する選択比が大きくなることも考えられる。 In etching a silicon-containing film such as amorphous silicon or silicon oxide, water added to a fluorine-based raw material for generating a fluorine-based reaction component (see Equation 4) or water generated by an etching reaction (see Equation 3) It adheres to the surface of the silicon-containing film and condenses. The etching reaction is inhibited where there is a condensed water layer. Therefore, the entire silicon-containing film cannot be etched uniformly, and a part of the silicon-containing film tends to remain in spots.
Although it may be possible to remove the moisture by performing a drying process every time moisture adheres to the surface of the silicon-containing film, the processing time becomes long and is not practical.
When the over-etching is sufficiently performed, the silicon content remaining in the spot shape can be removed by etching, but the base film is etched more than necessary.
Depending on the composition of the underlying film, it can be considered that the greater the moisture content, the greater the selectivity of the silicon-containing film to the underlying film.
　上記課題を解決するため、本発明は、シリコン含有膜が下地膜に積層された被処理物をエッチングする方法において、
　フッ素系反応成分を含む処理ガスを前記被処理物に接触させ、
　前記処理ガスの被処理物上での流速をエッチングの進行に応じて変化させることを特徴とする。
　エッチングにより水が生成される（式３参照）。また、処理ガスに水分が含まれている場合もある（式４参照）。ここで、処理ガスの被処理物上での流速を大きくすると、上記の水分が、処理ガスの勢いによって被処理物の表面から飛散して行きやすい。したがって、処理ガスの流速を調節することで被処理物の表面に付着する水分の量を調節できる。下地膜に影響しない段階ではシリコン含有膜のエッチングレートが良好な水分量になるよう処理ガスの流速を設定するとよい。これにより、処理時間を短縮できる。下地膜に影響する段階では、シリコン含有膜の下地膜に対するエッチングの選択比が大きな水分量になるよう処理ガスの流速を設定するとよい。これにより、下地膜のエッチングを抑制でき、かつシリコン含有膜が斑点状に残るのを防止できる。 In order to solve the above problems, the present invention provides a method for etching an object to be processed in which a silicon-containing film is laminated on a base film.
A treatment gas containing a fluorine-based reaction component is brought into contact with the object to be treated;
The flow rate of the processing gas on the object to be processed is changed according to the progress of etching.
Water is generated by etching (see Equation 3). In addition, the processing gas may contain moisture (see Formula 4). Here, when the flow velocity of the processing gas on the object to be processed is increased, the moisture is likely to be scattered from the surface of the object to be processed due to the momentum of the processing gas. Therefore, the amount of moisture adhering to the surface of the workpiece can be adjusted by adjusting the flow rate of the processing gas. At a stage where the base film is not affected, the flow rate of the processing gas is preferably set so that the etching rate of the silicon-containing film has a good moisture content. Thereby, processing time can be shortened. In the stage that affects the base film, the flow rate of the processing gas may be set so that the etching selection ratio of the silicon-containing film to the base film becomes a large amount of moisture. Thereby, the etching of the base film can be suppressed, and the silicon-containing film can be prevented from remaining in the form of spots.
　前記シリコン含有膜を構成するシリコン含有物として、シリコン（Ｓｉ）、酸化シリコン（ＳｉＯ２）、炭化シリコン（ＳｉＣ）、酸化炭化シリコン（ＳｉＯＣ）、炭化窒化シリコン（ＳｉＣＮ）等が挙げられる。シリコン（Ｓｉ）は、アモルファスシリコンでもよく、多結晶シリコンでもよく、単結晶シリコンでもよい。前記シリコン含有膜が、シリコン（Ｓｉ）、炭化シリコン（ＳｉＣ）、炭化酸化シリコン（ＳｉＯＣ）、炭化窒化シリコン（ＳｉＣＮ）等である場合、前記処理ガスが、酸化性反応成分を更に含むことが好ましい。酸化性反応成分は、シリコン等の物質に対し酸化作用を有するガス成分である。これにより、シリコン含有膜を酸化でき（式１参照）、その後、酸化シリコンと同様にしてエッチングできる（式３参照）。炭化シリコン（ＳｉＣ）や酸化炭化シリコン（ＳｉＯＣ）は、加熱によりシリコン（Ｓｉ）に変換でき、その後、シリコンと同様にしてエッチングできる（式１、式３参照）。酸化性反応成分としては、Ｏ３、Ｏラジカル、Ｈ２Ｏ２、Ｏ２、ＮＯ２、Ｎ２Ｏ等が挙げられ、好ましくはＯ３が挙げられる。 Examples of the silicon-containing material constituting the silicon-containing film include silicon (Si), silicon oxide (SiO 2 ), silicon carbide (SiC), silicon oxide carbide (SiOC), and silicon carbonitride (SiCN). Silicon (Si) may be amorphous silicon, polycrystalline silicon, or single crystal silicon. When the silicon-containing film is silicon (Si), silicon carbide (SiC), silicon carbide oxide (SiOC), silicon carbonitride (SiCN), or the like, it is preferable that the processing gas further includes an oxidizing reaction component. . The oxidizing reaction component is a gas component having an oxidizing action on a substance such as silicon. As a result, the silicon-containing film can be oxidized (see Equation 1) and then etched in the same manner as silicon oxide (see Equation 3). Silicon carbide (SiC) and silicon oxide carbide (SiOC) can be converted into silicon (Si) by heating and then etched in the same manner as silicon (see Equations 1 and 3). Examples of the oxidizing reaction component include O 3 , O radical, H 2 O 2 , O 2 , NO 2 , N 2 O, and the like, and preferably O 3 .
　下地膜は、エッチング対象のシリコン含有膜とは異なる成分で構成されていればよく、シリコン含有物であってもよい。エッチング対象のシリコン含有膜がシリコン（Ｓｉ）である場合、下地膜は、例えば酸化シリコン（ＳｉＯ２）、窒化シリコン（ＳｉＮ）等である。エッチング対象のシリコン含有膜が酸化シリコン（ＳｉＯ２）である場合、下地膜は、例えば窒化シリコン（ＳｉＮ）等である。エッチング対象のシリコン含有膜が炭化シリコン（ＳｉＣ）又は酸化炭化シリコン（ＳｉＯＣ）である場合、下地膜は、例えば窒化シリコン（ＳｉＮ）、酸化シリコン（ＳｉＯ２）等である。 The underlying film only needs to be composed of a component different from the silicon-containing film to be etched, and may be a silicon-containing material. When the silicon-containing film to be etched is silicon (Si), the base film is, for example, silicon oxide (SiO 2 ), silicon nitride (SiN), or the like. When the silicon-containing film to be etched is silicon oxide (SiO 2 ), the base film is, for example, silicon nitride (SiN). When the silicon-containing film to be etched is silicon carbide (SiC) or silicon oxide carbide (SiOC), the base film is, for example, silicon nitride (SiN), silicon oxide (SiO 2 ), or the like.
　前記流速をエッチングが進むにしたがって段階的に変化させるのが好ましい。これにより、流速の制御を容易化できる。「段階的」とは、前記流速の変化が不連続的ないしはステップ状であることを言う。
　前記流速をエッチングが進むにしたがって連続的に変化させてもよい。
　流速の変化は少なくとも１回あればよい。変化させるタイミングは、予め実験で決めておくのが好ましい。 It is preferable to change the flow rate stepwise as etching progresses. Thereby, control of the flow rate can be facilitated. “Stepwise” means that the change in flow rate is discontinuous or stepped.
The flow rate may be continuously changed as etching progresses.
The flow rate may be changed at least once. The timing for changing is preferably determined in advance by experiments.
　前記流速をエッチングが進むにしたがって大きくすることが好ましい。
　これによって、下地膜に影響しない段階では、処理ガスの流速を相対的に小さくし、被処理物の表面に付着する水分量を十分多くできる。したがって、シリコン含有膜のエッチングレートを高くできる。エッチングが進み、下地膜に影響する段階になると、処理ガスの流速を相対的に大きくすることで、被処理物の表面から水分を飛散させ、被処理物の表面の水分付着量を減少させることができる。下地膜が窒化シリコン等で構成されている場合、被処理物の表面の水分付着量の減少に伴なう下地膜のエッチングレートの低下の度合いは、シリコン等で構成されるシリコン含有膜より大きい。したがって、シリコン含有膜の下地膜に対するエッチングの選択比を大きくできる。これにより、下地膜のオーバーエッチングを抑制でき、かつシリコン含有膜の斑点状の残渣が出来るのを確実に防止できる。 The flow rate is preferably increased as etching progresses.
As a result, at a stage that does not affect the underlying film, the flow rate of the processing gas can be made relatively small, and the amount of water adhering to the surface of the object to be processed can be sufficiently increased. Therefore, the etching rate of the silicon-containing film can be increased. When etching progresses and affects the underlying film, the flow rate of the processing gas is relatively increased to dissipate moisture from the surface of the object to be processed and reduce the amount of moisture adhering to the surface of the object to be processed. Can do. When the base film is made of silicon nitride or the like, the degree of decrease in the etching rate of the base film due to the decrease in the amount of moisture adhering to the surface of the object to be processed is larger than the silicon-containing film made of silicon or the like. . Therefore, the etching selectivity of the silicon-containing film to the base film can be increased. As a result, overetching of the underlying film can be suppressed, and the occurrence of spotted residues in the silicon-containing film can be reliably prevented.
　前記流速をエッチングが進むにしたがって段階的に大きくするが好ましい。これにより、流速の制御を容易化できる。
　前記流速をエッチングが進むにしたがって連続的に漸増させてもよい。 The flow rate is preferably increased stepwise as etching progresses. Thereby, control of the flow rate can be facilitated.
The flow rate may be gradually increased as etching progresses.
　下地膜の成分等によっては、エッチングが進むにしたがってシリコン含有膜の下地膜に対する選択比を大きくするために、前記流速を段階的又は連続的に低くしてもよい。 Depending on the composition of the underlying film, the flow rate may be decreased stepwise or continuously in order to increase the selectivity of the silicon-containing film to the underlying film as etching proceeds.
　前記シリコン含有膜のエッチングすべき部分の大半（又はほぼ全体）をエッチングする期間（以下「第１エッチング工程」と称す）の前記流速を相対的に小さくし、前記シリコン含有膜のエッチングすべき部分のうち前記第１エッチング工程後に残った部分をエッチングする期間（以下「第２エッチング工程」と称す）の前記流速を相対的に大きくすることが好ましい。
　これによって、シリコン含有膜のエッチングすべき部分の大半をエッチングする際は、被処理物の表面に水分が付着しやすい状態にでき、エッチングレートを確実に高くできる。したがって、処理時間を確実に短縮できる。その後、残ったシリコン含有膜をエッチングする際は、被処理物の表面から水分を飛散させ、被処理物の表面の水分付着量を減少させることができる。したがって、下地膜が窒化シリコン等で構成されている場合、シリコン含有膜の下地膜に対する選択比を大きくできる。これにより、下地膜のオーバーエッチングを抑制でき、かつシリコン含有膜の斑点状の残渣が出来るのを確実に防止できる。
　ここで、「大半」とは、シリコン含有膜のエッチングすべき部分のうち例えば５０～９９．９％を言い、好ましくは７０～９９．９％を言い、より好ましくは８０～９９．９％を言い、一層好ましくは９０～９９．９％を言う。「ほぼ全体」とは、上記「大半」の上限部分であり、シリコン含有膜のエッチングすべき部分のうち例えば９０～９９．９％を言う。 The portion of the silicon-containing film to be etched is relatively reduced by relatively reducing the flow rate during a period (hereinafter referred to as “first etching step”) of etching most (or almost the whole) of the silicon-containing film to be etched. Of these, it is preferable to relatively increase the flow rate during a period of etching a portion remaining after the first etching step (hereinafter referred to as a “second etching step”).
Thus, when most of the portion to be etched of the silicon-containing film is etched, moisture can be easily attached to the surface of the object to be processed, and the etching rate can be reliably increased. Therefore, the processing time can be reliably shortened. Thereafter, when the remaining silicon-containing film is etched, moisture is scattered from the surface of the object to be processed, and the amount of moisture adhering to the surface of the object to be processed can be reduced. Therefore, when the base film is made of silicon nitride or the like, the selectivity of the silicon-containing film to the base film can be increased. As a result, overetching of the underlying film can be suppressed, and the occurrence of spotted residues in the silicon-containing film can be reliably prevented.
Here, “most” means, for example, 50 to 99.9%, preferably 70 to 99.9%, more preferably 80 to 99.9% of the portion to be etched of the silicon-containing film. More preferably 90 to 99.9%. The “substantially the entire” is the upper limit of the “most” and means, for example, 90 to 99.9% of the portion to be etched of the silicon-containing film.
　前記第１エッチング工程で前記流速を段階的に大きくし、前記第２エッチング工程での前記流速を前記第１エッチング工程の最終段階より大きくしてもよい。
　これによって、下地膜のオーバーエッチングを一層確実に抑制でき、かつシリコン含有膜の斑点状の残渣が出来るのを確実に防止できる。 The flow rate may be increased stepwise in the first etching step, and the flow rate in the second etching step may be increased from the final step of the first etching step.
As a result, over-etching of the underlying film can be more reliably suppressed, and the occurrence of spotted residues in the silicon-containing film can be reliably prevented.
　前記処理ガスの流量を変化させることにより、前記流速を変化させることが好ましい。
　これにより、簡易かつ確実に流速を変化させることができる。
　前記処理ガスの流量をエッチングが進むにしたがって大きくすることが好ましい。第１エッチング工程では処理ガスの流量を相対的に小さくし、第２エッチング工程では処理ガスの流量を相対的に大きくすることが好ましい。 It is preferable to change the flow rate by changing the flow rate of the processing gas.
Thereby, the flow velocity can be changed easily and reliably.
It is preferable to increase the flow rate of the processing gas as the etching progresses. It is preferable that the flow rate of the processing gas is relatively small in the first etching step, and the flow rate of the processing gas is relatively large in the second etching step.
　前記処理ガスに流速調節用ガスを混合し、又は混合を停止することで、処理ガスの流量を変化させることが好ましい。
　これによって、処理ガスの流量変化に拘わらず、処理ガス中の反応成分の流量についてはあまり変動しないようにでき、シリコン含有膜のエッチングレートの変動を抑制できる。
　前記流速調節用ガスの流量をエッチングが進むにしたがって大きくすることが好ましい。第１エッチング工程では流速調節用ガスの流量を相対的に小さくし、第２エッチング工程では流速調節用ガスの流量を相対的に大きくすることが好ましい。
　前記混合によって、前記流速調節用ガスが前記処理ガスの一成分となる。 It is preferable to change the flow rate of the processing gas by mixing a flow rate adjusting gas with the processing gas or stopping the mixing.
Accordingly, the flow rate of the reaction component in the process gas can be kept from changing much regardless of the change in the flow rate of the process gas, and the change in the etching rate of the silicon-containing film can be suppressed.
It is preferable to increase the flow rate of the flow rate adjusting gas as the etching progresses. It is preferable that the flow rate of the flow rate adjusting gas is relatively small in the first etching step, and the flow rate of the flow rate adjusting gas is relatively large in the second etching step.
By the mixing, the flow rate adjusting gas becomes a component of the processing gas.
　前記フッ素系反応成分が、フッ素系原料を含みＨ２Ｏが添加されたフッ素系原料ガスを大気圧近傍のプラズマ空間に通して生成されるようにしてもよい。
　前記プラズマ空間より上流側で前記フッ素系原料ガスに流速調節用ガスを混合し、又は混合を停止し、この流速調節用ガスの流量によって前記流速を調節することにしてもよい。
　フッ素系原料の流量については一定に維持できるため、フッ素系反応成分の生成量の変動を抑制でき、シリコン含有膜のエッチングレートの変動を抑制できる。この場合、流速調節用ガスは、フッ素系原料のための希釈ガスであってもよく、希釈ガスとは別のガスであってもよい。 The fluorine reaction components may be a fluorine-based raw material containing H 2 O and fluorine-based source gas added to be generated through the plasma space of approximately atmospheric pressure.
The flow rate adjusting gas may be mixed with the fluorine-based source gas upstream of the plasma space, or the mixing may be stopped, and the flow rate may be adjusted by the flow rate of the flow rate adjusting gas.
Since the flow rate of the fluorine-based raw material can be maintained constant, fluctuations in the amount of fluorine-based reaction components generated can be suppressed, and fluctuations in the etching rate of the silicon-containing film can be suppressed. In this case, the flow rate adjusting gas may be a dilution gas for the fluorine-based raw material, or may be a gas different from the dilution gas.
　前記プラズマ空間より下流側で前記処理ガスに流速調節用ガスを混合し、又は混合を停止し、この流速調節用ガスの流量によって前記流速を調節することが好ましい。
　この場合、前記流速の変化に拘らず、プラズマ空間に導入されるガスの各成分の流量比及び流量を一定に維持できる。これによって、プラズマ空間での放電を安定させることができる。よって、シリコン含有膜のエッチングレートの変動を一層確実に抑制できる。
　なお、第１エッチング工程における流速調節用ガスの流量はゼロであってもよい。 It is preferable that a flow rate adjusting gas is mixed with the processing gas downstream from the plasma space, or mixing is stopped, and the flow rate is adjusted by the flow rate of the flow rate adjusting gas.
In this case, the flow rate ratio and flow rate of each component of the gas introduced into the plasma space can be maintained constant regardless of the change in the flow velocity. Thereby, the discharge in the plasma space can be stabilized. Therefore, fluctuations in the etching rate of the silicon-containing film can be more reliably suppressed.
Note that the flow rate of the flow rate adjusting gas in the first etching step may be zero.
　本発明は、シリコン含有膜が下地膜に積層された被処理物をエッチングする装置において、
　フッ素系反応成分を含む処理ガスを前記被処理物に供給する処理ガス供給系と、
　前記処理ガスの被処理物上での流速をエッチングの進行に応じて変化させる流速調節手段と、
　を備えたことを他の特徴とする。
　この特徴によれば、前記流速の調節によって、被処理物の表面の水分付着量を調節できる。これによって、下地膜に影響しない段階ではシリコン含有膜のエッチングレートが良好になるように調節できる。したがって、処理時間を短縮できる。下地膜に影響する段階ではシリコン含有膜の下地膜に対する選択比が良好になるよう調節できる。したがって、下地膜のエッチングを抑制でき、かつシリコン含有膜の斑点状の残渣が出来るのを確実に防止できる。 The present invention provides an apparatus for etching an object to be processed in which a silicon-containing film is laminated on a base film.
A processing gas supply system for supplying a processing gas containing a fluorine-based reaction component to the object to be processed;
A flow rate adjusting means for changing the flow rate of the process gas on the workpiece according to the progress of etching;
The other feature is that
According to this feature, the amount of water adhesion on the surface of the workpiece can be adjusted by adjusting the flow rate. Thus, the etching rate of the silicon-containing film can be adjusted to be good at a stage that does not affect the base film. Therefore, the processing time can be shortened. At the stage of affecting the base film, the silicon-containing film can be adjusted to have a good selectivity with respect to the base film. Therefore, etching of the base film can be suppressed, and the occurrence of spotted residues in the silicon-containing film can be reliably prevented.
　前記流速調節手段が、前記流速をエッチングが進むにしたがって段階的に変化させることが好ましい。これによって、流速調節手段の制御を容易化できる。
　前記流速調節手段が、前記流速をエッチングが進むにしたがって連続的に変化させてもよい。 The flow rate adjusting means preferably changes the flow rate stepwise as etching progresses. Thereby, the control of the flow rate adjusting means can be facilitated.
The flow rate adjusting means may continuously change the flow rate as etching progresses.
　前記流速調節手段が、前記流速をエッチングが進むにしたがって大きくすることが好ましい。
　これによって、下地膜に影響しない段階では、処理ガスの流速を相対的に小さくし、被処理物の表面に付着する水分量を多くして、シリコン含有膜のエッチングレートを高くできる。したがって、処理時間を確実に短縮できる。エッチングが進み、下地膜に影響する段階になると、処理ガスの流速を相対的に大きくすることで、被処理物の表面から水分を飛散させ、被処理物の表面の水分付着量を減少させることができる。したがって、下地膜が窒化シリコン等で構成されている場合、シリコン含有膜の下地膜に対する選択比を大きくできる。これにより、下地膜のオーバーエッチングを抑制でき、かつシリコン含有膜の斑点状の残渣が出来るのを確実に防止できる。 It is preferable that the flow rate adjusting means increase the flow rate as etching progresses.
As a result, at a stage that does not affect the base film, the flow rate of the processing gas is relatively reduced, the amount of moisture attached to the surface of the object to be processed is increased, and the etching rate of the silicon-containing film can be increased. Therefore, the processing time can be reliably shortened. When etching progresses and affects the underlying film, the flow rate of the processing gas is relatively increased to dissipate moisture from the surface of the object to be processed and reduce the amount of moisture adhering to the surface of the object to be processed. Can do. Therefore, when the base film is made of silicon nitride or the like, the selectivity of the silicon-containing film to the base film can be increased. As a result, overetching of the underlying film can be suppressed, and the occurrence of spotted residues in the silicon-containing film can be reliably prevented.
　前記流速調節手段が、前記流速をエッチングが進むにしたがって段階的に大きくすることが好ましい。これによって、流速調節手段の制御を容易化できる。
　前記流速調節手段が、前記流速をエッチングが進むにしたがって連続的に漸増させてもよい。 It is preferable that the flow rate adjusting means increase the flow rate stepwise as etching progresses. Thereby, the control of the flow rate adjusting means can be facilitated.
The flow rate adjusting means may gradually increase the flow rate continuously as etching progresses.
　下地膜の成分等によっては、エッチングが進むにしたがってシリコン含有膜の下地膜に対する選択比を大きくするために、前記流速調節手段が前記流速を段階的又は連続的に小さくしてもよい。 Depending on the components of the underlying film, the flow rate adjusting means may decrease the flow rate stepwise or continuously in order to increase the selectivity of the silicon-containing film to the underlying film as etching proceeds.
　前記流速調節手段が、前記シリコン含有膜のエッチングすべき部分の大半がエッチングされる迄、前記流速を相対的に小さくし、残りのシリコン含有膜をエッチングするとき、前記流速を相対的に大きくすることが好ましい。
　これによって、シリコン含有膜のエッチングすべき部分の大半をエッチングする際は、被処理物の表面の水分付着量を大きくしてエッチングレートを確実に高くできる。したがって、処理時間を確実に短縮できる。その後、残ったシリコン含有膜をエッチングする際は、被処理物の表面から水分を飛散させ、被処理物の表面の水分付着量を減少させることができる。したがって、下地膜が窒化シリコン等で構成されている場合、シリコン含有膜の下地膜に対する選択比を大きくできる。これにより、下地膜のオーバーエッチングを抑制でき、かつシリコン含有膜の斑点状の残渣が出来るのを確実に防止できる。 The flow rate adjusting means reduces the flow rate relatively until most of the portion to be etched of the silicon-containing film is etched, and relatively increases the flow rate when etching the remaining silicon-containing film. It is preferable.
Thus, when most of the portion to be etched of the silicon-containing film is etched, the amount of moisture attached to the surface of the object to be processed can be increased to reliably increase the etching rate. Therefore, the processing time can be reliably shortened. Thereafter, when the remaining silicon-containing film is etched, moisture is scattered from the surface of the object to be processed, and the amount of moisture adhering to the surface of the object to be processed can be reduced. Therefore, when the base film is made of silicon nitride or the like, the selectivity of the silicon-containing film to the base film can be increased. As a result, overetching of the underlying film can be suppressed, and the occurrence of spotted residues in the silicon-containing film can be reliably prevented.
　前記流速調節手段が、前記処理ガスの流量を調節する流量調節手段であることが好ましい。
　これにより、流速調節手段を簡易な構造にでき、かつ流速を確実に変化させることができる。
　前記流速調節手段（流量調節手段）が、前記処理ガスの流量をエッチングが進むにしたがって大きくすることが好ましい。
　前記流速調節手段（流量調節手段）が、前記シリコン含有膜のエッチングすべき部分の大半がエッチングされる迄、前記処理ガスの流量を相対的に小さくし、残りのシリコン含有膜をエッチングするとき、前記処理ガスの流量を相対的に大きくすることが好ましい。前記流速調節手段が、前記処理ガスの流量をエッチングが進むにしたがって小さくしてもよい。 It is preferable that the flow rate adjusting means is a flow rate adjusting means for adjusting the flow rate of the processing gas.
As a result, the flow rate adjusting means can have a simple structure, and the flow rate can be reliably changed.
Preferably, the flow rate adjusting means (flow rate adjusting means) increases the flow rate of the processing gas as etching progresses.
When the flow rate adjusting means (flow rate adjusting means) relatively reduces the flow rate of the processing gas until most of the portion to be etched of the silicon-containing film is etched, and etches the remaining silicon-containing film, It is preferable to relatively increase the flow rate of the processing gas. The flow rate adjusting means may reduce the flow rate of the processing gas as etching progresses.
　前記処理ガス供給系が、大気圧近傍のプラズマ空間を形成するプラズマ生成部と、前記フッ素系反応成分となるフッ素系原料を含みＨ２Ｏが添加されたフッ素系原料ガスを前記プラズマ空間に導入する原料供給ラインと、を含むことが好ましい。
　前記流速調節手段が、前記原料供給ラインに流速調節用ガスを混合し、又は混合を停止し、この流速調節用ガスの流量によって前記流速を調節してもよい。
　これにより、フッ素系原料の流量については一定に維持できるため、フッ素系反応成分の生成量の変動を抑制でき、シリコン含有膜のエッチングレートの変動を抑制できる。
　前記流速調節用ガスは、前記処理ガスの一成分を構成する。 The processing gas supply system introduces into the plasma space a plasma generation unit that forms a plasma space near atmospheric pressure, and a fluorine-based source gas that includes a fluorine-based material that serves as the fluorine-based reaction component and to which H 2 O is added. And a raw material supply line.
The flow rate adjusting means may mix the flow rate adjusting gas into the raw material supply line or stop mixing, and adjust the flow rate according to the flow rate of the flow rate adjusting gas.
As a result, the flow rate of the fluorine-based raw material can be kept constant, so that fluctuations in the amount of fluorine-based reaction components generated can be suppressed, and fluctuations in the etching rate of the silicon-containing film can be suppressed.
The flow rate adjusting gas constitutes one component of the processing gas.
　前記流速調節部が、前記プラズマ空間より下流側の処理ガス供給系に流速調節用ガスを混合し、又は混合を停止し、この流速調節用ガスの流量によって前記流速を調節することが好ましい。
　これによって、前記流速の変化に拘らず、プラズマ空間に導入されるガスの各成分の流量比及び流量を一定に維持できる。したがって、プラズマ空間での放電を安定させることができる。よって、シリコン含有膜のエッチングレートの変動を一層確実に抑制できる。 It is preferable that the flow rate adjusting unit mix or stop mixing the flow rate adjusting gas into the processing gas supply system downstream of the plasma space, and adjust the flow rate according to the flow rate of the flow rate adjusting gas.
Accordingly, the flow rate ratio and flow rate of each component of the gas introduced into the plasma space can be maintained constant regardless of the change in the flow velocity. Therefore, the discharge in the plasma space can be stabilized. Therefore, fluctuations in the etching rate of the silicon-containing film can be more reliably suppressed.
　本発明は、シリコン含有膜が下地膜に積層された被処理物をエッチングする装置において、
　フッ素系反応成分を含む処理ガスを噴き出す複数の処理ガス供給系と、
　処理ガスが前記被処理物に吹き付けられる処理ガス供給系をエッチングの進行に応じて選択的に切り替える切替手段と、
　を備え、前記複数の処理ガス供給系のうち少なくとも２つの処理ガス供給系からの処理ガスが被処理物に吹き付けられたときの被処理物上での流速が互いに異なることを他の特徴とする。
　この特徴によれば、前記処理ガス供給系の選択によって、被処理物に吹き付けられた処理ガスの被処理物上での流速を調節できる。この流速の違いによって被処理物の表面の水分付着量を調節できる。これによって、下地膜に影響しない段階ではシリコン含有膜のエッチングレートが良好になるように調節できる。したがって、処理時間を短縮できる。下地膜に影響する段階ではシリコン含有膜の下地膜に対する選択比が良好になるよう調節できる。したがって、下地膜のエッチングを抑制でき、かつシリコン含有膜の斑点状の残渣が出来るのを確実に防止できる。 The present invention provides an apparatus for etching an object to be processed in which a silicon-containing film is laminated on a base film.
A plurality of processing gas supply systems for blowing out a processing gas containing a fluorine-based reaction component;
A switching means for selectively switching a processing gas supply system in which a processing gas is sprayed onto the object to be processed according to the progress of etching;
And having different flow rates on the object to be processed when the process gases from at least two of the plurality of process gas supply systems are sprayed on the object to be processed. .
According to this feature, the flow rate of the processing gas sprayed on the workpiece can be adjusted by selecting the processing gas supply system. The amount of moisture adhering to the surface of the workpiece can be adjusted by the difference in flow rate. Thus, the etching rate of the silicon-containing film can be adjusted to be good at a stage that does not affect the base film. Therefore, the processing time can be shortened. At the stage of affecting the base film, the silicon-containing film can be adjusted to have a good selectivity with respect to the base film. Therefore, etching of the base film can be suppressed, and the occurrence of spotted residues in the silicon-containing film can be reliably prevented.
　前記切替手段が、エッチングが進むにしたがって前記流速が相対的に大きい処理ガス供給系を選択することが好ましい。
　これによって、下地膜に影響しない段階では、流速が小さい供給系からの処理ガスを被処理物に吹き付けることで、被処理物の表面の水分付着量を大きくでき、シリコン含有膜のエッチングレートを確実に高くできる。したがって、処理時間を確実に短縮できる。エッチングが進み、下地膜に影響する段階になると、流速が大きい供給系からの処理ガスを被処理物に吹き付けることで、被処理物の表面から水分を飛散させ、被処理物の表面の水分付着量を減少させることができる。したがって、下地膜が窒化シリコン等で構成されている場合、シリコン含有膜の下地膜に対する選択比を大きくできる。これにより、下地膜のオーバーエッチングを抑制でき、かつシリコン含有膜の斑点状の残渣が出来るのを確実に防止できる。 It is preferable that the switching unit selects a processing gas supply system having a relatively high flow rate as etching progresses.
As a result, at a stage that does not affect the underlying film, the treatment gas from the supply system with a low flow rate is blown onto the object to be processed, so that the amount of moisture adhering to the surface of the object to be processed can be increased, and the etching rate of the silicon-containing film can be ensured. Can be expensive. Therefore, the processing time can be reliably shortened. When the etching progresses and affects the underlying film, the processing gas from the supply system with a high flow rate is blown onto the object to be processed, so that the water is scattered from the surface of the object to be processed and the water adheres to the surface of the object to be processed. The amount can be reduced. Therefore, when the base film is made of silicon nitride or the like, the selectivity of the silicon-containing film to the base film can be increased. As a result, overetching of the underlying film can be suppressed, and the occurrence of spotted residues in the silicon-containing film can be reliably prevented.
　前記切替手段が、前記シリコン含有膜のエッチングすべき部分の大半がエッチングされる迄、前記流速が相対的に小さい処理ガス供給系を選択し、残りのシリコン含有膜をエッチングするとき、前記流速が相対的に大きい処理ガス供給系を選択することが好ましい。　これによって、シリコン含有膜のエッチングすべき部分の大半をエッチングする際は、被処理物の表面の水分付着量を大きくしてエッチングレートを確実に高くできる。したがって、処理時間を確実に短縮できる。その後、残ったシリコン含有膜をエッチングする際は、被処理物の表面から水分を飛散させ、被処理物の表面の水分付着量を減少させることができる。したがって、下地膜が窒化シリコン等で構成されている場合、シリコン含有膜の下地膜に対する選択比を大きくできる。これにより、下地膜のオーバーエッチングを抑制でき、かつシリコン含有膜の斑点状の残渣が出来るのを確実に防止できる。 The switching means selects a processing gas supply system having a relatively low flow rate until most of the portion to be etched of the silicon-containing film is etched, and when the remaining silicon-containing film is etched, the flow rate is It is preferable to select a relatively large process gas supply system. Thus, when most of the portion to be etched of the silicon-containing film is etched, the amount of moisture attached to the surface of the object to be processed can be increased, and the etching rate can be reliably increased. Therefore, the processing time can be reliably shortened. Thereafter, when the remaining silicon-containing film is etched, moisture is scattered from the surface of the object to be processed, and the amount of moisture adhering to the surface of the object to be processed can be reduced. Therefore, when the base film is made of silicon nitride or the like, the selection ratio of the silicon-containing film to the base film can be increased. As a result, over-etching of the base film can be suppressed, and the occurrence of spotted residues in the silicon-containing film can be reliably prevented.
　前記複数の処理ガス供給系のうち少なくとも２つの処理ガス供給系の処理ガスの流量が、互いに異なることが好ましい。
　これにより、処理ガス供給系を切り替えて、被処理物に噴き付けられる処理ガスの流量を変えることで、被処理物上での処理ガスの流速を変化させることができる。前記切替手段が、エッチングが進むにしたがって処理ガスの流量が相対的に大きい処理ガス供給系を選択するのが好ましい。前記切替手段が、エッチングが進むにしたがって処理ガスの流量が相対的に小さい処理ガス供給系を選択することにしてもよい。 It is preferable that the flow rates of the processing gases of at least two processing gas supply systems among the plurality of processing gas supply systems are different from each other.
Thereby, the flow rate of the processing gas on the workpiece can be changed by switching the processing gas supply system and changing the flow rate of the processing gas sprayed on the workpiece. It is preferable that the switching unit selects a processing gas supply system in which the flow rate of the processing gas is relatively large as etching progresses. The switching means may select a processing gas supply system in which the flow rate of the processing gas is relatively small as etching progresses.
　各処理ガス供給系が、大気圧近傍のプラズマ空間を形成するプラズマ生成部と、前記フッ素系反応成分となるフッ素系原料を含みＨ２Ｏが添加されたフッ素系原料ガスを前記プラズマ空間に導入する原料供給ラインと、を含み、少なくとも１つの処理ガス供給系の原料供給ラインに流速調節用ガスを合流させる流速調節用ガス供給部が接続されていてもよい。
　上記流速調節用ガス供給部が接続された処理ガス供給系については、流速調節用ガス供給部が接続されていない処理ガス供給系より処理ガスの噴き出し流量を容易に大きくでき、ひいては被処理物上でのガス流速を容易に大きくできる。 Each processing gas supply system introduces into the plasma space a plasma generation unit that forms a plasma space near atmospheric pressure, and a fluorine-based source gas that includes a fluorine-based material that serves as the fluorine-based reaction component and to which H 2 O is added. A flow rate adjusting gas supply unit that joins the flow rate adjusting gas to the source supply line of at least one processing gas supply system.
For the processing gas supply system to which the flow rate adjusting gas supply unit is connected, it is possible to easily increase the flow rate of the processing gas from the processing gas supply system to which the flow rate adjusting gas supply unit is not connected, and as a result The gas flow rate at can be easily increased.
　各処理ガス供給系が、大気圧近傍のプラズマ空間を形成するプラズマ生成部と、前記フッ素系反応成分となるフッ素系原料を含みＨ２Ｏが添加されたフッ素系原料ガスを前記プラズマ空間に導入する原料供給ラインと、を含み、少なくとも１つの処理ガス供給系の前記プラズマ空間より下流側の処理ガス供給系に流速調節用ガスを合流させる流速調節用ガス供給部が接続されていることが好ましい。
　上記流速調節用ガス供給部が接続された処理ガス供給系については、流速調節用ガス供給部が接続されていない処理ガス供給系より処理ガスの噴き出し流量を容易に大きくでき、ひいては被処理物上でのガス流速を容易に大きくできる。しかも、上記流速調節用ガス供給部が接続された処理ガス供給系においてもプラズマ空間には流速調節用ガスが導入されることがなく、放電を安定させることができ、反応成分を安定的に生成できる。
　上記流速調節用ガス供給部が接続された処理ガス供給系が２つ以上あってもよい。その場合、これら２つ以上の処理ガス供給系のうち少なくとも２つの処理ガス供給系について、上記流速調節用ガス供給部からの流速調節用ガスの合流量を互いに異ならせてもよい。 Each processing gas supply system introduces into the plasma space a plasma generation unit that forms a plasma space near atmospheric pressure, and a fluorine-based source gas that includes a fluorine-based material that serves as the fluorine-based reaction component and to which H 2 O is added. A flow rate adjusting gas supply unit that joins the flow rate adjusting gas to the processing gas supply system downstream of the plasma space of the at least one processing gas supply system. .
For the processing gas supply system to which the flow rate adjusting gas supply unit is connected, it is possible to easily increase the flow rate of the processing gas from the processing gas supply system to which the flow rate adjusting gas supply unit is not connected, and as a result The gas flow rate at can be easily increased. Moreover, even in the processing gas supply system to which the flow rate adjusting gas supply unit is connected, the flow rate adjusting gas is not introduced into the plasma space, the discharge can be stabilized, and the reaction components can be generated stably. it can.
There may be two or more processing gas supply systems connected to the gas flow adjusting portion. In that case, the combined flow rate of the flow rate adjusting gas from the flow rate adjusting gas supply unit may be different for at least two of the two or more process gas supply systems.
　前記フッ素系原料としては、パーフルオロカーボン（ＰＦＣ）、ハイドロフルオロカーボン（ＨＦＣ）、ＳＦ６、ＮＦ３、ＸｅＦ２等が挙げられる。ＰＦＣとしては、ＣＦ４、Ｃ２Ｆ６、Ｃ３Ｆ６、Ｃ３Ｆ８等が挙げられる。ＨＦＣとしては、ＣＨＦ３、Ｃ２Ｈ２Ｆ２、ＣＨ３Ｆ等が挙げられる。
　Ｈ２Ｏに代えてＯＨ含有化合物を用いてもよい。ＯＨ基含有化合物としては、過酸化水素水、アルコール等が挙げられる。
　前記フッ素系原料の希釈ガスとしては、Ａｒ、Ｈｅ等の希ガスの他、Ｎ２等が挙げられる。
　フッ素系反応成分としては、ＨＦ、ＣＯＦ２等が挙げられる。希釈ガスを前記流速調節用ガスとして用い、希釈ガスの流量を変化させてもよい。 Examples of the fluorine-based raw material include perfluorocarbon (PFC), hydrofluorocarbon (HFC), SF 6 , NF 3 , and XeF 2 . Examples of the PFC include CF 4 , C 2 F 6 , C 3 F 6 , C 3 F 8 and the like. Examples of the HFC include CHF 3 , C 2 H 2 F 2 , and CH 3 F.
An OH-containing compound may be used in place of H 2 O. Examples of the OH group-containing compound include hydrogen peroxide water and alcohol.
Examples of the dilution gas for the fluorine-based material include N 2 and the like in addition to rare gases such as Ar and He.
Examples of the fluorine-based reaction component include HF, COF 2 and the like. A dilution gas may be used as the flow rate adjusting gas, and the flow rate of the dilution gas may be changed.
　前記シリコン含有物が、シリコン、炭化シリコン、酸化炭化シリコン、炭化窒化シリコン等である場合、前記処理ガス供給系が、フッ素系反応成分と酸化性反応成分を含む処理ガスを前記被処理物に供給することが好ましい。これにより、前記シリコン含有物を酸化性反応成分にて酸化でき（式１）、その後、フッ素系反応成分にてエッチングできる（式３）。
　前記シリコン含有物が、炭化シリコン、酸化炭化シリコン等である場合、加熱手段を更に備えることが好ましい。加熱手段で被処理物を加熱することで、炭化シリコン、酸化炭化シリコン等をシリコン化でき、その後、シリコン含有物がシリコンである場合と同様にしてエッチングできる。
　前記シリコン含有物が、シリコン、炭化シリコン、酸化炭化シリコン等である場合、前記原料供給ラインが、前記フッ素系原料ガスと、酸化性反応成分（Ｏ３、Ｏラジカル等）となる酸素系原料ガスとのうち少なくともフッ素系原料ガスを前記プラズマ空間に導入することが好ましい。 When the silicon-containing material is silicon, silicon carbide, silicon oxycarbide, silicon carbonitride, or the like, the processing gas supply system supplies a processing gas containing a fluorine-based reaction component and an oxidizing reaction component to the object to be processed. It is preferable to do. Thereby, the silicon-containing material can be oxidized with an oxidizing reaction component (Equation 1), and then etched with a fluorine-based reaction component (Equation 3).
When the silicon-containing material is silicon carbide, silicon oxide carbide, or the like, it is preferable to further include a heating unit. By heating the object to be processed with a heating means, silicon carbide, silicon oxide silicon carbide, or the like can be siliconized, and then etched in the same manner as when the silicon-containing material is silicon.
When the silicon-containing material is silicon, silicon carbide, silicon oxycarbide, or the like, the oxygen-based source gas in which the source supply line becomes the fluorine-based source gas and an oxidizing reaction component (O 3 , O radical, etc.) It is preferable to introduce at least a fluorine source gas into the plasma space.
　前記流速調節用ガスは、不活性ガス又は酸化性反応ガスであることが好ましい。
　不活性ガスとして、Ａｒ、Ｈｅ等の希ガスの他、窒素（Ｎ２）が挙げられる。ランニングコストを下げる観点からは、前記流速調節用ガスとなる不活性ガスとして、窒素を用いることが好ましい。 The flow rate adjusting gas is preferably an inert gas or an oxidizing reaction gas.
Examples of the inert gas include nitrogen (N 2 ) in addition to noble gases such as Ar and He. From the viewpoint of reducing the running cost, it is preferable to use nitrogen as the inert gas serving as the flow rate adjusting gas.
　酸化性反応ガスは、前記酸化性反応成分（オゾン（Ｏ３）、過酸化水素（Ｈ２Ｏ２）、酸素（Ｏ２）など）を含み、好ましくはオゾン（Ｏ３）を含む。酸化性反応ガスは、複数種の酸化性反応成分を含んでいてもよく、酸化性反応成分の原料成分を含んでいてもよい。例えば、酸化性反応ガスが、オゾン（Ｏ３）と酸素（Ｏ２）の混合ガスでもよい。更に、酸化性反応ガスが、窒素、Ａｒ等の不活性ガスを含んでいてもよい。 The oxidizing reaction gas contains the oxidizing reaction component (ozone (O 3 ), hydrogen peroxide (H 2 O 2 ), oxygen (O 2 ), etc.), and preferably contains ozone (O 3 ). The oxidizing reaction gas may contain a plurality of kinds of oxidizing reaction components, or may contain raw material components of the oxidizing reaction components. For example, the oxidizing reaction gas may be a mixed gas of ozone (O 3 ) and oxygen (O 2 ). Furthermore, the oxidizing reaction gas may contain an inert gas such as nitrogen or Ar.
　上述したように、シリコン（Ｓｉ）、炭化シリコン（ＳｉＣ）、炭化酸化シリコン（ＳｉＯＣ）、炭化窒化シリコン（ＳｉＣＮ）等の、酸化反応を経てエッチングされるシリコン含有膜においては、処理ガスが、前記酸化反応を起こすための酸化性反応ガスを含む。この場合、酸化性反応ガスの流量を変化させることにより、前記処理ガスの流量を変化させ、ひいては前記流速を変化させることにしてもよい。これによって、酸化性反応ガスを流速調節用ガスとしても代用することができる。したがって、流速調節専用のガスを別途に用意する必要がなく、使用するガス種を減らすことができる。また、処理ガス全体の流量変化に拘わらず、フッ素系原料ガス又はフッ素系反応ガスについては流量を一定に維持できる。したがって、シリコン含有膜のエッチングレートの変動を抑制できる。
　シリコン含有膜をエッチングするのに酸化性反応成分を必要としない場合でも、流速調節用ガスとして酸化性反応ガスを用いてもよい。 As described above, in a silicon-containing film etched through an oxidation reaction, such as silicon (Si), silicon carbide (SiC), silicon carbide oxide (SiOC), silicon carbonitride (SiCN), a processing gas is Contains an oxidizing reactive gas for causing an oxidation reaction. In this case, the flow rate of the oxidizing gas may be changed to change the flow rate of the processing gas, and thus the flow rate may be changed. As a result, the oxidizing reaction gas can be used as a flow rate adjusting gas. Therefore, it is not necessary to separately prepare a gas dedicated for adjusting the flow rate, and the type of gas used can be reduced. Further, the flow rate of the fluorine-based source gas or the fluorine-based reaction gas can be maintained constant regardless of the flow rate change of the entire processing gas. Therefore, fluctuations in the etching rate of the silicon-containing film can be suppressed.
Even when no oxidizing reaction component is required to etch the silicon-containing film, an oxidizing reaction gas may be used as the flow rate adjusting gas.
　前記処理ガス供給系が、前記フッ素系反応成分を含有するフッ素系反応ガスを前記被処理物に供給するフッ素系反応ガス供給系と、酸化性反応成分を含有する酸化性反応ガスを前記被処理物に供給する酸化性反応ガス供給系とを含み、前記流速調節手段が、前記酸化性反応ガス供給系の供給ガス流量を調節することにしてもよい。
　これによって、エッチングの進行に応じて、酸化性反応ガスの供給流量を変え、ひいては処理ガス全体の供給流量を変えることができる。この結果、処理ガスの流速を調節できる。酸化性反応ガスを、シリコン含有膜のエッチング（酸化反応）に用いるとともに、流速調節用ガスとしても用いることができる。したがって、流速調節専用のガスが不要であり、所要のガス種を減らすことができる。
　フッ素系反応ガス供給系と酸化性反応ガス供給系を別々に設けることで、酸化性反応ガスの流量調節に拘わらず、フッ素系反応ガス供給系によるフッ素系反応ガスの供給流量を一定に維持することができる。これによって、シリコン含有膜のエッチングレートの変動を抑制できる。 The process gas supply system supplies a fluorine-based reaction gas containing the fluorine-based reaction component to the object to be processed, and a fluorine-based reaction gas supply system that supplies the reaction object. The flow rate adjusting means may adjust the flow rate of the supply gas of the oxidizing reaction gas supply system.
As a result, the supply flow rate of the oxidizing reaction gas can be changed according to the progress of etching, and the supply flow rate of the entire process gas can be changed. As a result, the flow rate of the processing gas can be adjusted. The oxidizing reaction gas can be used for etching (oxidation reaction) of the silicon-containing film and also as a flow rate adjusting gas. Therefore, a gas dedicated to the flow rate adjustment is not necessary, and the required gas species can be reduced.
By separately providing a fluorine-based reactive gas supply system and an oxidizing reactive gas supply system, the flow rate of the fluorine-based reactive gas by the fluorine-based reactive gas supply system is maintained constant regardless of the flow rate control of the oxidizing reactive gas. be able to. Thereby, fluctuations in the etching rate of the silicon-containing film can be suppressed.
　酸化性反応ガスは、酸素系原料ガスを原料とし、プラズマ生成部やオゾナイザー等のガス励起装置によって生成できる。プラズマ生成部に酸素系原料ガスとして例えば酸素ガス（Ｏ２）を導入してプラズマ化することで、酸素ラジカル等の酸化性反応成分を含む酸化性反応ガスを生成できる。オゾナイザーに酸素系原料ガスとして酸素ガス（Ｏ２）を導入することで、オゾン含有ガスからなる酸化性反応ガスを生成できる。
　酸化性反応ガスを流速調節用ガスとして代用する場合、プラズマ放電部やオゾナイザーへの酸素系原料ガスの供給流量を調節するとよい。これによって、酸化性反応ガスの流量を調節でき、ひいては処理ガスの流量を調節できる。 The oxidizing reaction gas can be generated by a gas excitation device such as a plasma generation unit or an ozonizer using an oxygen-based source gas as a raw material. By introducing, for example, oxygen gas (O 2 ) as an oxygen-based source gas into the plasma generation unit to generate plasma, an oxidizing reaction gas containing an oxidizing reaction component such as oxygen radicals can be generated. By introducing oxygen gas (O 2 ) as an oxygen-based source gas into the ozonizer, an oxidizing reaction gas composed of an ozone-containing gas can be generated.
When the oxidizing reaction gas is used as a flow rate adjusting gas, the supply flow rate of the oxygen-based source gas to the plasma discharge unit or the ozonizer may be adjusted. As a result, the flow rate of the oxidizing reaction gas can be adjusted, and consequently the flow rate of the processing gas can be adjusted.
　酸素系原料ガスは、酸化性反応ガスの原料となるガスである。酸素系原料ガスとしては、Ｏ２、ＮＯ、ＮＯ２、Ｎ２Ｏ等が挙げられ、好ましくはＯ２が挙げられる。これら酸素系原料ガスは、それ自体が多少の酸化作用を有しており、酸化性反応ガスとしても機能する。 The oxygen-based source gas is a gas that is a raw material for the oxidizing reaction gas. Examples of the oxygen-based source gas include O 2 , NO, NO 2 , N 2 O and the like, preferably O 2 . These oxygen-based source gases themselves have some oxidizing action and function as oxidizing reaction gases.
　前記原料供給ラインが、前記フッ素系原料ガスと前記酸素系原料ガスを混合して前記プラズマ空間に導入するようになっていてもよい。
　酸素系原料ガスを前記原料供給ラインとは別のラインでプラズマ化、励起活性化、又はオゾン化し、前記酸化性反応成分を得ることにしてもよい。その場合、前記原料供給ラインからのフッ素系反応成分と前記別のラインからの酸化性反応成分とは混合したうえで被処理物に供給してもよく、別々の吹き出し口から被処理物に供給することにしてもよい。 The raw material supply line may be configured to mix and introduce the fluorine-based source gas and the oxygen-based source gas into the plasma space.
The oxidizing reaction component may be obtained by converting the oxygen-based source gas into plasma, excitation activation, or ozonization on a line different from the source supply line. In that case, the fluorine-based reaction component from the raw material supply line and the oxidizing reaction component from the other line may be mixed and supplied to the object to be processed, or supplied to the object to be processed from separate outlets. You may decide to do it.
　酸化性反応ガスを流速調節用ガスとして代用する場合、酸化性反応ガスを前記別のラインにて生成することが好ましい。これによって、フッ素系反応ガスの生成効率を、酸化性反応ガスの流量変化に拘わらず確実に一定に維持することができる。ひいては、シリコン含有膜のエッチングレートを安定させることができる。 When the oxidizing reaction gas is used as the flow rate adjusting gas, the oxidizing reaction gas is preferably generated in the separate line. As a result, the production efficiency of the fluorine-based reaction gas can be reliably maintained constant regardless of the flow rate change of the oxidizing reaction gas. As a result, the etching rate of the silicon-containing film can be stabilized.
　前記処理ガス供給系（又は前記酸化性反応ガス供給系）が、酸化性反応ガスを蓄えたボンベなどの容器を含んでいてもよい。この容器から酸化性反応ガスをそのまま被処理物に供給してもよい。これによって、酸化性反応ガスを生成するためのプラズマ放電部やオゾナイザーを省略できる。
　酸化性反応ガスを流速調節用ガスとして用いる場合は、前記容器からの酸化性反応ガスの供給流量を調節するとよい。前記容器からの酸化性反応ガス供給路は、フッ素系反応ガス生成用のプラズマ生成部より下流のフッ素系反応ガス供給路に合流させることが好ましい。 The processing gas supply system (or the oxidizing reaction gas supply system) may include a container such as a cylinder storing the oxidizing reaction gas. The oxidizing reaction gas may be supplied as it is from the container to the object to be processed. Thereby, the plasma discharge part and the ozonizer for generating the oxidizing reaction gas can be omitted.
When the oxidizing reaction gas is used as the flow rate adjusting gas, the supply flow rate of the oxidizing reaction gas from the container may be adjusted. The oxidizing reaction gas supply path from the vessel is preferably joined to the fluorine-based reaction gas supply path downstream from the plasma generation unit for generating the fluorine-based reaction gas.
　大気圧近傍とは、１．０１３×１０４～５０．６６３×１０４Ｐａの範囲を言い、圧力調整の容易化や装置構成の簡便化を考慮すると、１．３３３×１０４～１０．６６４×１０４Ｐａが好ましく、９．３３１×１０４～１０．３９７×１０４Ｐａがより好ましい。 The vicinity of atmospheric pressure refers to a range of 1.013 × 10 4 to 50.663 × 10 4 Pa, and 1.333 × 10 4 to 10.664 considering the ease of pressure adjustment and the simplification of the apparatus configuration. × 10 4 Pa is preferable, and 9.331 × 10 4 to 10.397 × 10 4 Pa is more preferable.
　本発明によれば、シリコン含有膜を残渣無く、かつ高レートでエッチングでき、しかも下地膜のエッチングを抑制できる。 According to the present invention, the silicon-containing film can be etched without residue and at a high rate, and etching of the base film can be suppressed.
図１は、本発明の第１実施形態の概略構成を示す解説図である。FIG. 1 is an explanatory diagram showing a schematic configuration of the first embodiment of the present invention. 図２（ａ）は、エッチング前の被処理物の断面図であり、図２（ｂ）は、第１エッチング工程の終了時の被処理物の平面図であり、図２（ｃ）は、図２（ｂ）の断面図であり、図２（ｄ）は、第２エッチング工程の終了時の被処理物の平面図である。2A is a cross-sectional view of the workpiece before etching, FIG. 2B is a plan view of the workpiece at the end of the first etching step, and FIG. It is sectional drawing of FIG.2 (b), FIG.2 (d) is a top view of the to-be-processed object at the time of completion | finish of a 2nd etching process. 図３は、本発明の第２実施形態の概略構成を示す解説図である。FIG. 3 is an explanatory diagram showing a schematic configuration of the second embodiment of the present invention. 図４は、本発明の第３実施形態の概略構成を示す解説図である。FIG. 4 is an explanatory diagram showing a schematic configuration of the third embodiment of the present invention. 図５は、本発明の第４実施形態の概略構成を示す解説図である。FIG. 5 is an explanatory diagram showing a schematic configuration of the fourth embodiment of the present invention. 図６は、本発明の第５実施形態の概略構成を示す解説図である。FIG. 6 is an explanatory diagram showing a schematic configuration of the fifth embodiment of the present invention. 図７は、本発明の第６実施形態の概略構成を示す解説図である。FIG. 7 is an explanatory diagram showing a schematic configuration of the sixth embodiment of the present invention. 図８は、本発明の第７実施形態の概略構成を示す解説図である。FIG. 8 is an explanatory diagram showing a schematic configuration of the seventh embodiment of the present invention. 図９は、本発明の第８実施形態の概略構成を示す解説図である。FIG. 9 is an explanatory diagram showing a schematic configuration of the eighth embodiment of the present invention. 図１０は、実施例２の結果を示すグラフである。FIG. 10 is a graph showing the results of Example 2. 図１１は、実施例３の結果を示すグラフである。FIG. 11 is a graph showing the results of Example 3.
発明を実施するための形態BEST MODE FOR CARRYING OUT THE INVENTION
　以下、本発明の実施形態を説明する。
第１実施形態
　本発明は、被処理物に形成されたシリコン含有膜のエッチングに適用される。
　図２（ａ）は、エッチング前の被処理物９０の一例を示したものである。被処理物９０は、例えばフラットパネルディスプレイ用のガラスを基板９１とし、このガラス基板９１上に下地膜９２が形成され、この下地膜９２上にエッチング対象のシリコン含有膜９３が積層されている。下地膜９２は、例えば窒化シリコン（ＳｉＮｘ）からなる。エッチング対象のシリコン含有膜９３は、例えばアモルファスシリコン（ａ－Ｓｉ）からなる。図示は省略するが、被処理物９０のシリコン含有膜９３のうちエッチングすべきでない部分にはレジスト等のマスクが被せられている。シリコン含有膜９３のうちマスクされていない部分が、エッチングされるべき部分となる。 Embodiments of the present invention will be described below.
First Embodiment The present invention is applied to etching a silicon-containing film formed on an object to be processed.
FIG. 2A shows an example of the workpiece 90 before etching. The object 90 to be processed includes, for example, glass for flat panel display as a substrate 91, a base film 92 is formed on the glass substrate 91, and a silicon-containing film 93 to be etched is laminated on the base film 92. The base film 92 is made of, for example, silicon nitride (SiNx). The silicon-containing film 93 to be etched is made of, for example, amorphous silicon (a-Si). Although illustration is omitted, a portion of the silicon-containing film 93 of the workpiece 90 that should not be etched is covered with a mask such as a resist. A portion of the silicon-containing film 93 that is not masked becomes a portion to be etched.
　図１は、シリコン含有膜９３のエッチングに用いるエッチング装置１の一例を示したものである。エッチング装置１は、処理ガス供給系１０と、支持部２０を備えている。支持部２０によって被処理物９０が支持されている。支持部２０は例えばステージで構成されている。支持部２０の内部に加熱部２１が設けられている。加熱部２１によって被処理物９０を加熱することができる。 FIG. 1 shows an example of an etching apparatus 1 used for etching the silicon-containing film 93. The etching apparatus 1 includes a processing gas supply system 10 and a support unit 20. The workpiece 90 is supported by the support unit 20. The support part 20 is composed of a stage, for example. A heating unit 21 is provided inside the support unit 20. The workpiece 90 can be heated by the heating unit 21.
　処理ガス供給系１０は、原料供給ライン３０と、プラズマ生成部４０を含んでいる。原料供給ライン３０の上流端にはフッ素系原料供給部３１が設けられている。フッ素系原料供給部３１は、フッ素系原料ガスを原料供給ライン３０に送出する。フッ素系原料として、ＣＦ４、ＣＨＦ３、Ｃ２Ｆ６、Ｃ３Ｆ８、ＳＦ６、ＮＦ３、ＸｅＦ２などが挙げられる。ここでは、フッ素系原料としてＣＦ４が用いられている。フッ素系原料は、Ａｒ、Ｈｅ、Ｎ２等の希釈ガスで希釈されていてもよく、希釈されていなくてもよい。ここでは、フッ素系原料ガスとしてＡｒで希釈されたＣＦ４が用いられている。ＣＦ４とＡｒの体積混合比は、ＣＦ４：Ａｒ＝５：９５～８０：２０が好ましく、ＣＦ４：Ａｒ＝１０：９０～３０：７０がより好ましい。 The processing gas supply system 10 includes a raw material supply line 30 and a plasma generation unit 40. A fluorine-based material supply unit 31 is provided at the upstream end of the material supply line 30. The fluorine-based material supply unit 31 sends a fluorine-based material gas to the material supply line 30. Examples of the fluorine-based raw material include CF 4 , CHF 3 , C 2 F 6 , C 3 F 8 , SF 6 , NF 3 , and XeF 2 . Here, CF 4 is used as the fluorine-based material. The fluorine-based raw material may be diluted with a diluent gas such as Ar, He, N 2 or the like, or may not be diluted. Here, CF 4 diluted with Ar is used as the fluorine-based source gas. The volume mixing ratio of CF 4 and Ar is preferably CF 4 : Ar = 5: 95 to 80:20, and more preferably CF 4 : Ar = 10: 90 to 30:70.
　原料供給ライン３０には、添加部３２が接続されている。添加部３２は、液体の水（Ｈ２Ｏ）を蓄えた加湿器で構成され、液体の水を気化させて、原料供給ライン３０のフッ素系原料ガス（ＣＦ４＋Ａｒ）に添加するようになっている。添加の方法として、原料供給ライン３０を流れるフッ素系原料ガスの一部を添加部３２に分流させ、この分流ガスを添加部３２の液面に接触させて、水を分流ガス中に気化させてもよく、分流ガスを添加部３２の水中でバブリングさせて水を気化させてもよい。水をヒータで加熱して気化させ原料供給ライン３０に供給してもよい。 An addition unit 32 is connected to the raw material supply line 30. The addition unit 32 is configured by a humidifier that stores liquid water (H 2 O), vaporizes the liquid water, and adds it to the fluorine-based source gas (CF 4 + Ar) in the source supply line 30. ing. As a method of addition, a part of the fluorine-based raw material gas flowing through the raw material supply line 30 is diverted to the addition unit 32, and this diverted gas is brought into contact with the liquid surface of the addition unit 32 to vaporize water into the diversion gas. Alternatively, the diverted gas may be bubbled in the water of the addition unit 32 to vaporize the water. Water may be vaporized by heating with a heater and supplied to the raw material supply line 30.
　原料供給ライン３０の添加部３２より下流側に酸素系原料供給部３４が連なっている。原料供給部３４は、酸素系原料ガスを原料供給ライン３０に供給する。これにより、原料供給ライン３０内でフッ素系原料ガスと酸素系原料ガスとが混合される。酸素系原料として、Ｏ２、ＮＯ、ＮＯ２、Ｎ２Ｏ等が挙げられる。ここでは、酸素系原料ガスとしてＯ２ガスが用いられている。酸素系原料供給部３４の原料供給ライン３０への接続箇所は、添加部３２より上流側であってもよい。 An oxygen-based raw material supply unit 34 is connected downstream from the addition unit 32 of the raw material supply line 30. The raw material supply unit 34 supplies an oxygen-based raw material gas to the raw material supply line 30. Thereby, the fluorine-based source gas and the oxygen-based source gas are mixed in the source supply line 30. Examples of the oxygen-based raw material include O 2 , NO, NO 2 , and N 2 O. Here, O 2 gas is used as the oxygen-based source gas. The connection point of the oxygen-based material supply unit 34 to the material supply line 30 may be upstream of the addition unit 32.
　原料供給ライン３０には、流速調節用ガス供給部６０（流速調節手段）が接続されている。流速調節用ガス供給部６０の原料供給ライン３０への接続箇所は、水添加部３２より下流側であり、かつ酸素系原料供給部３４との接続部より下流側であるが、これに限定されるものではなく、酸素系原料供給部３４より上流側であってもよく、水添加部３２より上流側であってもよい。 The raw material supply line 30 is connected to a flow rate adjusting gas supply unit 60 (flow rate adjusting means). The connection point of the flow rate adjusting gas supply unit 60 to the raw material supply line 30 is on the downstream side of the water addition unit 32 and on the downstream side of the connection unit with the oxygen-based raw material supply unit 34, but is not limited thereto. It may be upstream from the oxygen-based raw material supply unit 34, or may be upstream from the water addition unit 32.
　流速調節用ガス供給部６０は、流速調節用ガスを蓄えている。流速調節用ガスは、不活性ガスであることが好ましい。不活性ガスとして、Ａｒ、Ｈｅ等の希ガスの他、Ｎ２が挙げられる。ここでは、流速調節用ガスとしてＮ２が用いられている。 The flow rate adjusting gas supply unit 60 stores a flow rate adjusting gas. The flow rate adjusting gas is preferably an inert gas. Examples of the inert gas include N 2 in addition to noble gases such as Ar and He. Here, N 2 is used as the flow rate adjusting gas.
　流速調節用ガス供給部６０は、原料供給ライン３０に流速調節用ガスを混合する混合モードと、混合を停止する停止モードの２つの状態をとり得る。詳細な図示は省略するが、流速調節用ガス供給部６０には開閉弁や流量制御弁が設けられている。これら弁によって、混合モードと停止モードの何れかを選択したり、混合モードにおける流速調節用ガス（Ｎ２）の流量を調節したりするようになっている。フッ素系原料ガス（ＣＦ４＋Ａｒ）と流速調節用ガス（Ｎ２）との混合比は、（ＣＦ４＋Ａｒ）：Ｎ２＝１０：１～２：１の範囲で設定するのが好ましい。 The flow rate adjusting gas supply unit 60 can take two states: a mixing mode in which the flow rate adjusting gas is mixed in the raw material supply line 30 and a stop mode in which mixing is stopped. Although detailed illustration is omitted, the flow rate adjusting gas supply unit 60 is provided with an on-off valve and a flow rate control valve. With these valves, either the mixing mode or the stop mode is selected, and the flow rate of the flow rate adjusting gas (N 2 ) in the mixing mode is adjusted. The mixing ratio of the fluorine-based source gas (CF 4 + Ar) and the flow rate adjusting gas (N 2 ) is preferably set in the range of (CF 4 + Ar): N 2 = 10: 1 to 2: 1.
　原料供給ライン３０の下流端は、プラズマ生成部４０へ延びている。
　プラズマ生成部４０は、互いに対向する一対の電極４１，４１を有している。少なくとも一方の電極４１の対向面には固体誘電体層（図示せず）が設けられている。これら電極４１，４１のうち一方は、電源４２に接続され、他方は、電気的に接地されている。電源４２からの電圧供給によって電極４１，４１間の空間４３が大気圧近傍のプラズマ空間となる。プラズマ空間４３の上流端に原料供給ライン３０が連なっている。プラズマ空間４３の下流端にはノズルからなる噴出部５９が設けられている。噴出部５９は、支持部２０上の被処理物９０に面している。噴出部５９が、支持部２０の両端間を往復するように支持部２０に対し相対移動（スキャン）されるようになっていてもよい。 The downstream end of the raw material supply line 30 extends to the plasma generation unit 40.
The plasma generation unit 40 has a pair of electrodes 41 and 41 facing each other. A solid dielectric layer (not shown) is provided on the facing surface of at least one of the electrodes 41. One of these electrodes 41, 41 is connected to a power source 42, and the other is electrically grounded. By supplying voltage from the power source 42, the space 43 between the electrodes 41 and 41 becomes a plasma space near atmospheric pressure. A raw material supply line 30 is connected to the upstream end of the plasma space 43. At the downstream end of the plasma space 43, an ejection portion 59 made of a nozzle is provided. The ejection part 59 faces the workpiece 90 on the support part 20. The ejection part 59 may be relatively moved (scanned) with respect to the support part 20 so as to reciprocate between both ends of the support part 20.
　図示は省略するが、噴出部５９の底面はある程度の面積を持ち、被処理物９０との間にガス路を画成する。噴出部５９の開口から噴き出された処理ガスは、上記ガス路内を被処理物９０の表面に沿って噴出部５９の開口から離れる方向へ流れるようになっている。 Although illustration is omitted, the bottom surface of the ejection portion 59 has a certain area, and defines a gas path between the workpiece 90 and the workpiece. The processing gas ejected from the opening of the ejection part 59 flows in a direction away from the opening of the ejection part 59 along the surface of the workpiece 90 in the gas path.
　上記構成のエッチング装置１を用いて、被処理物９０のシリコン含有膜９３をエッチングする方法を説明する。
　エッチングの工程は、エッチングの初期から中期（終期に至る前）までの第１エッチング工程と、エッチング終期に行なう第２エッチング工程とに分けられる。 A method of etching the silicon-containing film 93 of the workpiece 90 using the etching apparatus 1 having the above configuration will be described.
The etching process is divided into a first etching process from the initial stage to the middle stage (before reaching the final stage) of etching and a second etching process performed at the final stage of etching.
［第１エッチング工程］
　第１エッチング工程では、フッ素系原料供給部３１からフッ素系原料ガス（ＣＦ４＋Ａｒ）を原料供給ライン３０に送出する。このフッ素系原料ガスに、添加部３２によって水（Ｈ２Ｏ）を添加する。水の添加量を添加部３２によって調節する。水の添加量は、結露が生じない程度になるべく多くする。好ましくは、フッ素系原料ガスが露点温度１０～５０℃の水分を含むようにする。フッ素系原料ガスの露点温度は、雰囲気温度や被処理物９０の温度より低いことが好ましい。これによって、原料供給ライン３０を構成する配管内や被処理物９０の表面上での結露を防止することができる。被処理物９０を加熱部２１によって加熱せず、室温にする場合、フッ素系原料ガスの露点が１５～２０℃になるようにするのが好ましい。 [First etching step]
In the first etching step, a fluorine-based source gas (CF 4 + Ar) is sent from the fluorine-based source supply unit 31 to the source supply line 30. Water (H 2 O) is added to the fluorine-based source gas by the addition unit 32. The addition amount of water is adjusted by the addition unit 32. The amount of water added is increased as much as possible without causing condensation. Preferably, the fluorine source gas contains water having a dew point temperature of 10 to 50 ° C. The dew point temperature of the fluorine-based source gas is preferably lower than the ambient temperature or the temperature of the workpiece 90. Thereby, dew condensation can be prevented in the piping constituting the raw material supply line 30 and on the surface of the workpiece 90. When the object to be processed 90 is not heated by the heating unit 21 and is brought to room temperature, it is preferable that the dew point of the fluorine-based source gas is 15 to 20 ° C.
　水を添加した後のフッ素系原料ガス（ＣＦ４＋Ａｒ＋Ｈ２Ｏ）に、酸素系原料供給部３４からの酸素系原料ガス（Ｏ２）を混合し、混合原料ガスを生成する。フッ素系原料ガスと酸素系原料ガスの体積混合比は、フッ素系原料ガス：酸素系原料ガス＝１：９～９：１が好ましく、フッ素系原料ガス：酸素系原料ガス＝１：２～２：１がより好ましい。水の体積比率はフッ素系原料ガス及び酸素系原料ガスに対して十分に小さいため、水を添加する前のフッ素系原料ガスと酸素系原料ガスとの体積比と、水を添加した後のフッ素系原料ガスと酸素系原料ガスとの体積比とは、ほとんど同じである。 The oxygen-based material gas (O 2 ) from the oxygen-based material supply unit 34 is mixed with the fluorine-based material gas (CF 4 + Ar + H 2 O) after adding water to generate a mixed material gas. The volume mixing ratio of the fluorine-based source gas and the oxygen-based source gas is preferably fluorine-based source gas: oxygen-based source gas = 1: 9 to 9: 1, and fluorine-based source gas: oxygen-based source gas = 1: 2 to 2 : 1 is more preferable. Since the volume ratio of water is sufficiently small with respect to the fluorine-based source gas and the oxygen-based source gas, the volume ratio between the fluorine-based source gas and the oxygen-based source gas before adding water and the fluorine after adding water The volume ratio of the system material gas and the oxygen system material gas is almost the same.
　第１エッチング工程では、流速調節用ガス供給部６０を停止モードにし、流速調節用ガス（Ｎ２）の原料供給ライン３０への混合を停止しておく。上記の混合原料ガス（ＣＦ４＋Ａｒ＋Ｏ２＋Ｈ２Ｏ）は、流速調節用ガス（Ｎ２）が混合されることなく、そのまま原料供給ライン３０の下流端から電極間空間４３に導入される。 In the first etching step, the flow rate adjusting gas supply unit 60 is set to a stop mode, and mixing of the flow rate adjusting gas (N 2 ) into the raw material supply line 30 is stopped. The mixed raw material gas (CF 4 + Ar + O 2 + H 2 O) is introduced as it is into the inter-electrode space 43 from the downstream end of the raw material supply line 30 without being mixed with the flow rate adjusting gas (N 2 ).
　併行して、電源４２から電極４１に電圧を供給し、電極間空間４３内に大気圧近傍プラズマを生成する。これによって、混合ガスがプラズマ化（分解、励起、活性化、ラジカル化、イオン化等を含む）され、フッ素系反応成分と酸化性反応成分を含む処理ガスが生成される。以下、第１エッチング工程の処理ガスを、適宜「第１処理ガス」と称す。第１処理ガスは、シリコン９３を高レートでエッチングできるレシピになっている。フッ素系反応成分としては、ＨＦ、ＣＯＦ２等が挙げられる。これらフッ素系反応成分は、主にＣＦ４及びＨ２Ｏが分解して生成されたものである。酸化性反応成分としては、Ｏ３、Ｏラジカル等が挙げられる。これら酸化性反応成分は、主にＯ２を原料として生成されたものである。 At the same time, a voltage is supplied from the power source 42 to the electrode 41, and plasma near atmospheric pressure is generated in the interelectrode space 43. Thereby, the mixed gas is turned into plasma (including decomposition, excitation, activation, radicalization, ionization, etc.), and a processing gas containing a fluorine-based reaction component and an oxidizing reaction component is generated. Hereinafter, the processing gas in the first etching step is appropriately referred to as “first processing gas”. The first processing gas is a recipe that can etch the silicon 93 at a high rate. Examples of the fluorine-based reaction component include HF, COF 2 and the like. These fluorine-based reaction components are mainly produced by the decomposition of CF 4 and H 2 O. Examples of the oxidizing reaction component include O 3 and O radicals. These oxidizing reaction components are mainly produced using O 2 as a raw material.
　第１処理ガスが、プラズマ生成部４０から噴き出され、支持部２０上の被処理物９０に噴き付けられる。第１処理ガスは被処理物９０の表面上を流れる。被処理物９０の表面上でのガス流速は、後記の第２エッチング工程より小さい。この第１処理ガス中の酸化性反応成分が、アモルファスシリコンからなるシリコン含有膜９３と接触し、シリコンの酸化反応が起き、酸化シリコンが生成される（式１）。この酸化シリコンにフッ素系反応成分が接触し（式３）、揮発性のＳｉＦ４が生成される。こうして、シリコン含有膜９３が良好なエッチングレートでエッチングされていく。 The first processing gas is ejected from the plasma generation unit 40 and sprayed onto the workpiece 90 on the support unit 20. The first processing gas flows on the surface of the workpiece 90. The gas flow rate on the surface of the workpiece 90 is smaller than the second etching step described later. The oxidizing reaction component in the first processing gas comes into contact with the silicon-containing film 93 made of amorphous silicon, and an oxidation reaction of silicon occurs to generate silicon oxide (Formula 1). A fluorine-based reaction component comes into contact with this silicon oxide (formula 3), and volatile SiF 4 is generated. Thus, the silicon-containing film 93 is etched at a good etching rate.
　第１処理ガスには、プラズマ空間４３内で分解されなかった混合原料ガスの成分も含まれており、したがって水も含まれている。この水の一部は、フッ素系反応成分のＣＯＦ２と反応してＨＦを生成し（式２）、シリコンのエッチングに寄与する。残りの水の一部は、被処理物９０の表面に付着して凝縮する。また、ＨＦによるエッチング反応（式３）によって水が生成され、この水の一部も被処理物９０の表面に付着して凝縮する。これによって、被処理物９０の表面に水の凝縮層が形成される。第１処理ガスの被処理物９０上での流速は、被処理物９０の表面上の水分をあまり飛散させない程度の大きさである。よって、凝縮層を適度な厚さにでき、シリコンのエッチングレートを十分高くすることができる。 The first processing gas also contains a component of the mixed raw material gas that has not been decomposed in the plasma space 43, and thus also contains water. A part of this water reacts with the fluorine-based reaction component COF 2 to generate HF (Equation 2) and contributes to the etching of silicon. A part of the remaining water adheres to the surface of the workpiece 90 and condenses. Further, water is generated by the etching reaction (formula 3) by HF, and a part of this water adheres to the surface of the workpiece 90 and condenses. Thereby, a condensed layer of water is formed on the surface of the workpiece 90. The flow rate of the first processing gas on the workpiece 90 is large enough to prevent the moisture on the surface of the workpiece 90 from scattering too much. Therefore, the condensed layer can be made to an appropriate thickness, and the silicon etching rate can be made sufficiently high.
　一方、被処理物９０の表面のところどころで水の凝縮層が必要以上に厚くなることがある。凝縮層が厚い箇所では、エッチング反応が阻害される。そのため、図２（ｂ）及び同図（ｃ）に示すように、エッチングが終期に至る直前の被処理物９０の表面には、下地膜９２が露出した箇所と、エッチングすべきシリコン含有膜９３が未だ残っている箇所とが出来る。残ったシリコン含有膜９３を、残膜９３ａと称す。残膜９３ａは、斑点状（まだら状）になっている。 On the other hand, the water condensate layer may become thicker than necessary at the surface of the workpiece 90. The etching reaction is hindered where the condensed layer is thick. Therefore, as shown in FIGS. 2B and 2C, the surface of the workpiece 90 just before the etching reaches the final stage, the portion where the base film 92 is exposed, and the silicon-containing film 93 to be etched. Can still be left. The remaining silicon-containing film 93 is referred to as a remaining film 93a. The remaining film 93a has a spotted shape (a mottled shape).
［第２エッチング工程］
　図２（ｂ）及び同図（ｃ）に示すように、エッチングが進み、下地膜９２の一部が露出したとき、又は露出する直前に、第１エッチング工程から第２エッチング工程に切り替える。下地膜９２の露出や下地膜９２上に残っているシリコン含有膜９３の厚みを検知して第２エッチング工程に切り替えてもよいし、予め実験などにより切り替えるタイミングを決めておき、そのタイミングで第２エッチング工程に切り替えてもよい。 [Second etching step]
As shown in FIGS. 2B and 2C, when the etching progresses and a part of the base film 92 is exposed or just before it is exposed, the first etching process is switched to the second etching process. The exposure of the base film 92 and the thickness of the silicon-containing film 93 remaining on the base film 92 may be detected to switch to the second etching process. You may switch to 2 etching processes.
　第２エッチング工程では、流速調節用ガス供給部６０を混合モードにする。それ以外の動作及び処理条件については第１エッチング工程と好ましくは同じにする。したがって、第１エッチング工程と同成分かつ同流量の混合原料ガス（ＣＦ４＋Ａｒ＋Ｏ２＋Ｈ２Ｏ）に流速調節用ガス供給部６０から流速調節用ガス（Ｎ２）が混合される。これにより、原料ガスの流量が増える。 In the second etching step, the flow rate adjusting gas supply unit 60 is set to the mixed mode. Other operations and processing conditions are preferably the same as those in the first etching step. Therefore, the flow rate adjusting gas (N 2 ) is mixed from the flow rate adjusting gas supply unit 60 to the mixed source gas (CF 4 + Ar + O 2 + H 2 O) having the same component and the same flow rate as the first etching step. Thereby, the flow volume of source gas increases.
　混合後の原料ガス（ＣＦ４＋Ａｒ＋Ｏ２＋Ｈ２Ｏ＋Ｎ２）をプラズマ空間４３に導入してプラズマ化する。これにより、ＨＦ、ＣＯＦ２等のフッ素系反応成分と、Ｏ３、Ｏラジカル等の酸化性反応成分を含む処理ガスが生成される。以下、第２エッチング工程の処理ガスを、適宜「第２処理ガス」と称す。第２処理ガスの流量は、流速調節用ガス（Ｎ２）の混合分だけ第１エッチング工程における第１処理ガスの流量より大きい。第２処理ガス中のフッ素系反応成分（ＨＦ等）及び酸化性反応成分（Ｏ３等）の量は、第１エッチング工程と略等しい。 The mixed raw material gas (CF 4 + Ar + O 2 + H 2 O + N 2 ) is introduced into the plasma space 43 to be converted into plasma. As a result, a processing gas containing a fluorine-based reaction component such as HF or COF 2 and an oxidizing reaction component such as O 3 or O radical is generated. Hereinafter, the processing gas in the second etching step is appropriately referred to as “second processing gas”. The flow rate of the second processing gas is larger than the flow rate of the first processing gas in the first etching step by the amount of the mixed flow rate adjusting gas (N 2 ). The amounts of the fluorine-based reaction component (such as HF) and the oxidizing reaction component (such as O 3 ) in the second processing gas are substantially equal to those in the first etching step.
　この第２処理ガスを噴出部５９から噴き出し、被処理物９０に吹き付ける。ガス流量が増大したのに対し、噴出部５９の開口度は一定であるため、第２処理ガスの噴出部５９からの吹き出し速度は、第１エッチング工程での第１処理ガスの吹き出し速度より大きくなる。さらに、第２処理ガスは、被処理物９０の表面上を流れる。ガス流量が増大したのに対し、噴出部５９と被処理物９０との間の距離（ワーキングディスタンス）は一定であるため、第２処理ガスの被処理物９０の表面上での流速は、第１エッチング工程での第１処理ガスの流速より大きくなる。 The second processing gas is ejected from the ejection part 59 and sprayed onto the workpiece 90. Although the gas flow rate is increased, the opening degree of the ejection part 59 is constant, so that the blowing speed of the second processing gas from the ejection part 59 is larger than the blowing speed of the first processing gas in the first etching step. Become. Further, the second processing gas flows on the surface of the workpiece 90. While the gas flow rate has increased, the distance (working distance) between the ejection portion 59 and the object to be processed 90 is constant, so the flow rate of the second processing gas on the surface of the object to be processed 90 is It becomes larger than the flow velocity of the first processing gas in one etching process.
　ガス流速の増大によって、被処理物９０の表面上の水分が飛散されやすくなる。したがって、被処理物９０の表面の水分付着量が第１エッチング工程より小さくなり、凝縮層の厚さが第１エッチング工程より小さくなる。凝縮層が減少すると、下地の窒化シリコン膜９２のエッチングレートが低下する。この窒化シリコンのエッチングレートの低下度合いは、シリコンの凝縮層減少に伴なうエッチングレートの低下度合いより大きい。したがって、エッチング対象膜９３の下地膜９２に対する選択比を大きくできる。また、第２処理ガス中のフッ素系反応成分（ＨＦ等）及び酸化性反応成分（Ｏ３等）の量は第１エッチング工程と略等しいため、シリコンのエッチングレートの低下を抑制できる。これにより、図２（ｃ）に示すように、斑点状の残膜９３ａを良好なエッチングレートで選択的にエッチングして除去でき、下地膜９２のオーバーエッチング量ｄを小さくできる。 Due to the increase in the gas flow rate, moisture on the surface of the workpiece 90 is likely to be scattered. Therefore, the amount of moisture adhering to the surface of the workpiece 90 is smaller than that in the first etching step, and the thickness of the condensed layer is smaller than that in the first etching step. As the condensed layer decreases, the etching rate of the underlying silicon nitride film 92 decreases. The degree of decrease in the etching rate of silicon nitride is greater than the degree of decrease in the etching rate associated with the decrease in the silicon condensation layer. Therefore, the selection ratio of the etching target film 93 to the base film 92 can be increased. Moreover, since the amount of the fluorine-based reaction component (HF or the like) and the oxidizing reaction component (O 3 or the like) in the second processing gas is substantially equal to that in the first etching step, it is possible to suppress a decrease in the etching rate of silicon. As a result, as shown in FIG. 2C, the spot-like residual film 93a can be selectively etched and removed at a good etching rate, and the overetching amount d of the base film 92 can be reduced.
　第１エッチング工程から第２エッチング工程への切替は、流速調節用ガス供給部６０を停止モードから混合モードに切り替えるだけで容易に行なうことができ、例えば添加部３２によって水の添加率を変えるよりも応答性が良好である。 Switching from the first etching step to the second etching step can be easily performed only by switching the flow rate adjusting gas supply unit 60 from the stop mode to the mixing mode. For example, the addition unit 32 changes the water addition rate. Is also responsive.
　次に、本発明の他の実施形態を説明する。以下の実施形態において、既述の実施形態と重複する構成に関しては、図面に同一符号を付して説明を適宜省略する。
第２実施形態
　図３に示すように、第２実施形態では、流速調節用ガスの処理ガス供給系１０への混合箇所が第１実施形態（図１）と異なっている。流速調節用ガス供給部６０は、プラズマ生成部４０より上流側の原料供給ライン３０にではなく、プラズマ生成部４０より下流側の噴出ライン５０に接続されている。 Next, another embodiment of the present invention will be described. In the following embodiments, the same reference numerals are given to the drawings, and the description thereof is omitted as appropriate for the same configurations as those of the above-described embodiments.
Second Embodiment As shown in FIG. 3, the second embodiment is different from the first embodiment (FIG. 1) in the mixing location of the flow rate adjusting gas into the processing gas supply system 10. The flow rate adjusting gas supply unit 60 is connected not to the raw material supply line 30 upstream of the plasma generation unit 40 but to the ejection line 50 downstream of the plasma generation unit 40.
　噴出ライン５０は、プラズマ空間４３から延びている。噴出ライン５０の下流端に噴出部５９が設けられている。噴出ライン５０の中間部に流速調節用ガス供給部６０が接続されている。 The ejection line 50 extends from the plasma space 43. A jet part 59 is provided at the downstream end of the jet line 50. A flow rate adjusting gas supply unit 60 is connected to an intermediate portion of the ejection line 50.
　流速調節用ガス供給部６０は、第１エッチング工程では停止モードになる。したがって、第１エッチング工程の動作は、第１実施形態と同じである。 The flow rate adjusting gas supply unit 60 is in a stop mode in the first etching step. Therefore, the operation of the first etching process is the same as that of the first embodiment.
　第２エッチング工程では流速調節用ガス供給部６０が混合モードになる。原料供給ライン３０では、第１エッチング工程と同一成分かつ同一流量の混合原料ガス（ＣＦ４＋Ａｒ＋Ｏ２＋Ｈ２Ｏ）を生成し、プラズマ生成部４０に導入する。プラズマ生成部４０への導入前の混合原料ガスに流速調節用ガスが混合されることはない。したがって、第１エッチング工程から第２エッチング工程に切り替わっても、プラズマ空間４３でのガス状態が変化することはなく、放電を安定させることができる。 In the second etching step, the flow rate adjusting gas supply unit 60 is in a mixed mode. In the raw material supply line 30, a mixed raw material gas (CF 4 + Ar + O 2 + H 2 O) having the same component and the same flow rate as the first etching step is generated and introduced into the plasma generation unit 40. The flow rate adjusting gas is not mixed with the mixed raw material gas before being introduced into the plasma generating unit 40. Therefore, even when the first etching process is switched to the second etching process, the gas state in the plasma space 43 does not change, and the discharge can be stabilized.
　プラズマ空間４３でのプラズマ化により、フッ素系反応成分（ＨＦ等）及び酸化性反応成分（Ｏ３等）を含む処理ガスを得る。これら反応成分の生成量は、第１エッチング工程と同じにできる。 By processing into plasma in the plasma space 43, a processing gas containing a fluorine-based reaction component (HF or the like) and an oxidizing reaction component (O 3 or the like) is obtained. The amount of these reaction components generated can be the same as in the first etching step.
　この処理ガスを噴出ライン５０に導出する。この処理ガスに供給部６０から流速調節用ガス（Ｎ２）を混合する。これにより、処理ガスの流量が増大する。したがって、第１実施形態の第２エッチング工程と同様に、被処理物９０上でのガス流速を大きくすることができる。 This processing gas is led out to the ejection line 50. The processing gas is mixed with a flow rate adjusting gas (N 2 ) from the supply unit 60. As a result, the flow rate of the processing gas increases. Therefore, similarly to the second etching step of the first embodiment, the gas flow rate on the workpiece 90 can be increased.
第３実施形態
　図４に示すように、第３実施形態の処理ガス供給系１０は、フッ素系反応成分と酸化性反応成分とを別々に生成するようになっている。処理ガス供給系１０は、フッ素系反応ガス供給系３３と、酸化性反応ガス供給系３５を別々に有している。フッ素系反応ガス供給系３３は、原料供給ライン３０と、プラズマ生成部４０と、フッ素系噴出路５１とを含む。原料供給ライン３０は、酸素系原料供給部３４が接続されていない点を除き、第２実施形態（図３）と同じになっている。フッ素系噴出路５１に流速調節用ガス供給部６０が接続されている。原料供給ライン３０は、フッ素系原料ガス（ＣＦ４＋Ａｒ＋Ｈ２Ｏ）だけをプラズマ生成部４０に導入する。プラズマ生成部４０には酸素系原料ガスは導入されない。プラズマ生成部４０のプラズマ空間４３の下流端からフッ素系噴出路５１が延びている。 Third Embodiment As shown in FIG. 4, the processing gas supply system 10 of the third embodiment generates a fluorine-based reaction component and an oxidizing reaction component separately. The processing gas supply system 10 has a fluorine-based reaction gas supply system 33 and an oxidizing reaction gas supply system 35 separately. The fluorine-based reactive gas supply system 33 includes a raw material supply line 30, a plasma generation unit 40, and a fluorine-based ejection path 51. The raw material supply line 30 is the same as that of the second embodiment (FIG. 3) except that the oxygen-based raw material supply unit 34 is not connected. A flow rate adjusting gas supply unit 60 is connected to the fluorine-based jet passage 51. The material supply line 30 introduces only the fluorine-based material gas (CF 4 + Ar + H 2 O) into the plasma generation unit 40. The oxygen-based source gas is not introduced into the plasma generation unit 40. A fluorine-based ejection path 51 extends from the downstream end of the plasma space 43 of the plasma generation unit 40.
　酸化性反応ガス供給系３５は、酸素系原料供給部３４と、プラズマ生成部４０とは別のプラズマ生成部４４と、酸素系噴出路５２とを含む。
　プラズマ生成部４４は、互いに対向する一対の電極４５，４５を有している。少なくとも一方の電極４５の対向面には固体誘電体層（図示せず）が設けられている。これら電極４５，４５のうち一方は、電源４６に接続され、他方は、電気的に接地されている。電源４６からの電圧供給によって電極４５，４５間の空間４７が大気圧近傍のプラズマ空間となる。プラズマ空間４７の上流端に酸素系原料供給部３４が連なっている。プラズマ生成部４４のプラズマ空間４７の下流端から酸素系噴出路５２が延びている。 The oxidizing reaction gas supply system 35 includes an oxygen-based material supply unit 34, a plasma generation unit 44 different from the plasma generation unit 40, and an oxygen-based ejection path 52.
The plasma generation unit 44 has a pair of electrodes 45 and 45 facing each other. A solid dielectric layer (not shown) is provided on the opposing surface of at least one of the electrodes 45. One of these electrodes 45, 45 is connected to a power source 46, and the other is electrically grounded. By supplying voltage from the power supply 46, the space 47 between the electrodes 45 and 45 becomes a plasma space near atmospheric pressure. An oxygen-based material supply unit 34 is connected to the upstream end of the plasma space 47. An oxygen-based ejection path 52 extends from the downstream end of the plasma space 47 of the plasma generation unit 44.
　フッ素系反応ガス供給系３３の噴出路５１と酸化性反応ガス供給系３５の噴出路５２が互いに合流している。この合流部に共通噴出部５３が連なっている。共通噴出部５３が、支持部２０上の被処理物９０に面している。共通噴出部５３が、支持部２０の両端間を往復するように支持部２０に対し相対移動されるようになっていてもよい。 The ejection path 51 of the fluorine-based reaction gas supply system 33 and the ejection path 52 of the oxidizing reaction gas supply system 35 are joined together. The common jet part 53 is continued to this merge part. The common ejection part 53 faces the workpiece 90 on the support part 20. The common ejection part 53 may be moved relative to the support part 20 so as to reciprocate between both ends of the support part 20.
　第３実施形態では、フッ素系反応ガス供給系３３において、フッ素系原料ガス（ＣＦ４＋Ａｒ＋Ｈ２Ｏ）をプラズマ生成部４０でプラズマ化して、フッ素系反応成分（ＨＦ等）を含むフッ素系反応ガスを生成し、噴出路５１に導出する。これと併行して、酸化性反応ガス供給系３５において、酸素系原料供給部３４からの酸素系原料ガス（Ｏ２）をプラズマ生成部４４のプラズマ空間４７に導入してプラズマ化し、酸化性反応成分（Ｏ３等）を含む酸化性反応ガスを生成する。この酸化性反応ガスをプラズマ生成部４４から噴出路５２に導出し、噴出路５１からのフッ素系反応ガスと混合する。フッ素系反応ガスと酸化性反応ガスの体積混合比は、フッ素系反応ガス：酸化性反応ガス＝１：９～９：１が好ましく、フッ素系反応ガス：酸化性反応ガス＝１：２～２：１がより好ましい。混合により、フッ素系反応成分及び酸化性反応成分を含む処理ガスが得られる。この処理ガスを噴出部５３から被処理物９０に噴き付ける。 In the third embodiment, in the fluorine-based reaction gas supply system 33, the fluorine-based source gas (CF 4 + Ar + H 2 O) is converted into plasma by the plasma generation unit 40, and a fluorine-based reaction gas containing a fluorine-based reaction component (HF or the like). Is generated and led to the ejection path 51. At the same time, in the oxidizing reaction gas supply system 35, the oxygen-based source gas (O 2 ) from the oxygen-based source supply unit 34 is introduced into the plasma space 47 of the plasma generation unit 44 to be converted into plasma, and the oxidation reaction occurs. An oxidizing reaction gas containing components (such as O 3 ) is generated. This oxidizing reaction gas is led out from the plasma generation unit 44 to the ejection path 52 and mixed with the fluorine-based reaction gas from the ejection path 51. The volume mixing ratio of the fluorine-based reaction gas and the oxidizing reaction gas is preferably fluorine-based reaction gas: oxidation reaction gas = 1: 9 to 9: 1, and the fluorine-based reaction gas: oxidation reaction gas = 1: 2 to 2 : 1 is more preferable. By mixing, a processing gas containing a fluorine-based reaction component and an oxidizing reaction component is obtained. This processing gas is sprayed from the ejection part 53 to the workpiece 90.
　第３実施形態では、フッ素系原料ガスと酸素系原料ガスを別々のプラズマ生成部４０，４４でプラズマ化するため、フッ素系反応成分の生成量と酸化性反応成分の生成量をそれぞれ十分に大きくすることができる。これにより、第１、第２の各エッチング工程でのシリコン含有膜９３のエッチングレートを高めることができ、処理時間を一層短縮することができる。 In the third embodiment, since the fluorine-based source gas and the oxygen-based source gas are converted into plasma by separate plasma generation units 40 and 44, the generation amount of the fluorine-based reaction component and the generation amount of the oxidizing reaction component are sufficiently large. can do. Thereby, the etching rate of the silicon-containing film 93 in each of the first and second etching steps can be increased, and the processing time can be further shortened.
　第３実施形態において、第１エッチング工程では流速調節用ガス供給部６０が停止モードになり、第２エッチング工程では流速調節用ガス供給部６０が混合モードになる点は、既述の実施形態と同様である。したがって、第２エッチング工程では、供給部６０からの流速調節用ガス（Ｎ２）が、噴出路５１に導入され、フッ素系反応ガスと混合される。 In the third embodiment, the flow rate adjusting gas supply unit 60 is in the stop mode in the first etching step, and the flow rate adjusting gas supply unit 60 is in the mixed mode in the second etching step. It is the same. Therefore, in the second etching step, the flow rate adjusting gas (N 2 ) from the supply unit 60 is introduced into the ejection path 51 and mixed with the fluorine-based reaction gas.
第４実施形態
　図５に示すように、第４実施形態では、酸化性反応ガス供給系３５における酸化性反応ガスの生成装置としてプラズマ生成部４４に代えてオゾナイザー４８が用いられている。酸素系原料供給部３４からの酸素ガス（Ｏ２）がオゾナイザー４８に導入され、Ｏ３を含む酸化性反応ガスが生成され、この酸化性反応ガスが噴出路５２に導出されるようになっている。
　その他の構成及び動作は、第３実施形態（図４）と同様である。 Fourth Embodiment As shown in FIG. 5, in the fourth embodiment, an ozonizer 48 is used in place of the plasma generation unit 44 as an oxidizing reaction gas generating device in the oxidizing reaction gas supply system 35. Oxygen gas (O 2 ) from the oxygen-based raw material supply unit 34 is introduced into the ozonizer 48 to generate an oxidizing reaction gas containing O 3 , and this oxidizing reaction gas is led out to the ejection path 52. Yes.
Other configurations and operations are the same as those of the third embodiment (FIG. 4).
第５実施形態
　図６に示すように、第５実施形態のエッチング装置１は、複数（２つ）の処理ガス供給系１０を備えている。各処理ガス供給系１０は、第１、第２実施形態（図１、図３）の処理ガス供給系１０と略同じ構成になっている。２つの供給系１０を区別するときは、第１の処理ガス供給系１０Ａの各構成要素には、既述の実施形態の処理ガス供給系１０における対応する構成要素と同じ符号にＡを付し、第２の処理ガス供給系１０Ｂの各構成要素には、既述の実施形態の処理ガス供給系１０における対応する構成要素と同じ符号にＢを付す。 Fifth Embodiment As shown in FIG. 6, the etching apparatus 1 of the fifth embodiment includes a plurality (two) of processing gas supply systems 10. Each processing gas supply system 10 has substantially the same configuration as the processing gas supply system 10 of the first and second embodiments (FIGS. 1 and 3). When distinguishing between the two supply systems 10, each component of the first process gas supply system 10 </ b> A is denoted by the same reference numeral as the corresponding component in the process gas supply system 10 of the above-described embodiment. The constituent elements of the second processing gas supply system 10B are denoted by the same reference numerals as those of the corresponding constituent elements in the processing gas supply system 10 of the above-described embodiment.
　第１処理ガス供給系１０Ａが第１、第２実施形態（図１、図３）の処理ガス供給系１０と異なっているところは、流速調節用ガス供給部６０が接続されていない点である。したがって、第１処理ガス供給系１０Ａからは、流速調節用ガス（Ｎ２）を含まない第１処理ガスが常時噴き出される。この供給系１０Ａからの第１処理ガスの成分及び流量は、第１、第２実施形態の第１エッチング工程における第１処理ガスと同じである。 The first processing gas supply system 10A is different from the processing gas supply system 10 of the first and second embodiments (FIGS. 1 and 3) in that the flow rate adjusting gas supply unit 60 is not connected. . Therefore, the first processing gas that does not contain the flow rate adjusting gas (N 2 ) is constantly ejected from the first processing gas supply system 10A. The component and flow rate of the first processing gas from the supply system 10A are the same as the first processing gas in the first etching step of the first and second embodiments.
　第２処理ガス供給系１０Ｂは、第２実施形態（図３）の処理ガス供給系１０と同一構成になっている。ただし、第２処理ガス供給系１０Ｂの流速調節用ガス供給部６０Ｂは、常時混合モードで運転されるようになっている。したがって、第２処理ガス供給系１０Ｂからは、流速調節用ガス（Ｎ２）を含む第２処理ガスが常時噴き出される。この供給系１０Ｂからの第２処理ガスの成分及び流量は、第１、第２実施形態の第２エッチング工程における第２処理ガスと同じである。 The second processing gas supply system 10B has the same configuration as the processing gas supply system 10 of the second embodiment (FIG. 3). However, the flow rate adjusting gas supply unit 60B of the second processing gas supply system 10B is always operated in the mixed mode. Therefore, the second processing gas including the flow rate adjusting gas (N 2 ) is constantly ejected from the second processing gas supply system 10B. The component and flow rate of the second processing gas from the supply system 10B are the same as the second processing gas in the second etching process of the first and second embodiments.
　第１処理ガス供給系１０Ａの噴き出し流量は、流速調節用ガスを混合しない分だけ相対的に小さく、第２処理ガス供給系１０Ｂの噴き出し流量は、流速調節用ガスの混合分だけ相対的に大きい。一方、第１処理ガス供給系１０Ａの噴出部５９Ａの開口度と、第２処理ガス供給系１０Ｂの噴出部５９Ａの開口度は、互いに等しい。したがって、第１処理ガス供給系１０Ａからの吹き出し流速は相対的に小さい。第２処理ガス供給系１０Ａからの吹き出し流速は相対的に大きい。 The ejection flow rate of the first processing gas supply system 10A is relatively small by the amount not mixed with the flow rate adjusting gas, and the ejection flow rate of the second processing gas supply system 10B is relatively large by the mixing amount of the flow rate adjusting gas. . On the other hand, the opening degree of the ejection part 59A of the first processing gas supply system 10A and the opening degree of the ejection part 59A of the second processing gas supply system 10B are equal to each other. Therefore, the blow-off flow rate from the first processing gas supply system 10A is relatively small. The blowing flow rate from the second processing gas supply system 10A is relatively large.
　支持部２０には移動手段２２が接続されている。詳細な図示は省略するが、移動手段２２は、例えばモータ等の駆動部と、この駆動部によって進退されるスライド部とを有し、スライド部に支持部２０が接続されている。移動手段２２によって、支持部２０が、第１処理ガスの噴出部５９Ａと対向する第１位置（図６の実線）と、第２処理ガスの噴出部５９Ａと対向する第２位置（図６の二点鎖線）との間で移動されるようになっている。 The moving means 22 is connected to the support part 20. Although detailed illustration is omitted, the moving means 22 includes, for example, a drive unit such as a motor and a slide unit that is advanced and retracted by the drive unit, and the support unit 20 is connected to the slide unit. The moving unit 22 causes the support unit 20 to have a first position (solid line in FIG. 6) facing the first processing gas ejection part 59A and a second position (in FIG. 6) facing the second processing gas ejection part 59A. It is designed to move between the two-dot chain line).
　第１エッチング工程では、移動手段２２によって支持部２０を第１位置に位置させる。これによって、第１処理ガス供給系１０Ａから噴き出された第１処理ガスが被処理物９０に接触する。この第１処理ガスの噴き出し流速ひいては被処理物９０上での流速は比較的小さい。したがって、被処理物９０の表面に適度な厚さの水の凝縮層が形成されやすく、シリコン含有膜９３のエッチングレートを高くできる。 In the first etching step, the support unit 20 is positioned at the first position by the moving means 22. As a result, the first processing gas ejected from the first processing gas supply system 10 </ b> A contacts the workpiece 90. The flow rate of the first processing gas is relatively low, and the flow rate on the workpiece 90 is relatively small. Therefore, a condensed layer of water having an appropriate thickness is easily formed on the surface of the workpiece 90, and the etching rate of the silicon-containing film 93 can be increased.
　シリコン含有膜９３の大半がエッチングされた時点で、移動手段２２によって支持部２０を第１位置から第２位置に移動させる。これによって、第１エッチング工程から第２エッチング工程に時間をほとんど置かずに移行することができる。第２エッチング工程では、第２処理ガス供給系１０Ｂから噴き出された第２処理ガスが被処理物９０に接触する。
この第２処理ガスの噴き出し流速ひいては被処理物９０上での流速は、上記第１処理ガス供給系１０Ａのガス流速より大きい。したがって、被処理物９０の表面から水分を飛散させることができ、被処理物９０の表面に水の凝縮層が形成されるのを抑制できる。よって、シリコンの窒化シリコンに対する選択比を大きくでき、下地膜９２のオーバーエッチングを抑制しつつ、残膜９３ａを選択的にエッチングできる。
　移動手段２２は、処理ガスが被処理物９０に吹き付けられる処理ガス供給系１０Ａ，１０Ｂを選択的に切り替える切替手段を構成する。
　支持部２０の移動速度や、第１エッチング工程で用いられる処理ガス供給系１０の数は、予め実験により第１エッチング工程で下地膜９２が露出し出すように、または下地膜９２上に残っているシリコン含有膜９３の厚みが極わずかになるように決めておく。 When most of the silicon-containing film 93 is etched, the support unit 20 is moved from the first position to the second position by the moving means 22. Thereby, it is possible to shift from the first etching process to the second etching process with little time. In the second etching step, the second processing gas ejected from the second processing gas supply system 10 </ b> B comes into contact with the workpiece 90.
The flow rate of the second process gas is higher than the gas flow rate of the first process gas supply system 10A. Therefore, moisture can be scattered from the surface of the object to be processed 90, and formation of a condensed layer of water on the surface of the object to be processed 90 can be suppressed. Therefore, the selection ratio of silicon to silicon nitride can be increased, and the remaining film 93a can be selectively etched while suppressing overetching of the base film 92.
The moving unit 22 constitutes a switching unit that selectively switches between the processing gas supply systems 10 </ b> A and 10 </ b> B through which the processing gas is blown onto the workpiece 90.
The moving speed of the support part 20 and the number of the processing gas supply systems 10 used in the first etching step are determined in advance so that the base film 92 is exposed in the first etching step or is left on the base film 92 by experiments. The thickness of the silicon-containing film 93 is determined to be extremely small.
　移動手段２２が、支持部２０に代えて噴出部５９Ａ，５９Ｂに接続されていてもよく、支持部２０を第１位置と第２位置との間で移動させるのに代えて、噴出部５９Ａ，５９Ｂを移動させることにより、第１エッチング工程では噴出部５９Ａを支持部２０と対向させ、第２エッチング工程では噴出部５９Ｂを支持部２０と対向させてもよい。 The moving means 22 may be connected to the ejection parts 59A, 59B instead of the support part 20, and instead of moving the support part 20 between the first position and the second position, the ejection parts 59A, By moving 59B, the ejection part 59A may be opposed to the support part 20 in the first etching process, and the ejection part 59B may be opposed to the support part 20 in the second etching process.
第６実施形態
　図７に示すように、第６実施形態では、被処理物９４が連続シート状になっている。連続シート状の被処理物９４は、繰り出しロール２３から繰り出され、巻き取りロール２４に巻き取られるようになっている。ロール２３，２４の間の被処理物９４の裏側に加熱部２１が設けられている。 Sixth Embodiment As shown in FIG. 7, in the sixth embodiment, the workpiece 94 is a continuous sheet. The continuous sheet-like workpiece 94 is fed from the feed roll 23 and taken up by the take-up roll 24. A heating unit 21 is provided on the back side of the workpiece 94 between the rolls 23 and 24.
　ロール２３，２４の間の繰り出しロール２３寄りの位置に第１処理ガス供給系１０Ａの噴出部５９Ａが配置されている。ロール２３，２４の間の巻き取りロール２４寄りの位置に第２処理ガス供給系１０Ｂの噴出部５９Ｂが配置されている。 The ejection part 59A of the first processing gas supply system 10A is disposed at a position between the rolls 23 and 24 near the feeding roll 23. An ejection portion 59B of the second processing gas supply system 10B is disposed at a position near the take-up roll 24 between the rolls 23 and 24.
　繰り出しロール２３から繰り出された被処理物９４は、第１処理ガス供給系１０Ａからの小流量、低速の第１処理ガスと接触する。その後、第２処理ガス供給系１０Ｂからの大流量、高速の第２処理ガスと接触する。これによって、第１エッチング工程から第２エッチング工程に連続的に移行することができる。繰り出しロール２３及び巻き取りロール２４は、ステージ状の支持部２０に代わる被処理物支持部として機能する。かつ、繰り出しロール２３及び巻き取りロール２４は、処理ガスが被処理物９０に吹き付けられる処理ガス供給系１０Ａ，１０Ｂを選択的に切り替える切替手段を構成する。 The workpiece 94 fed out from the feed roll 23 comes into contact with the low-flow first processing gas at a low flow rate from the first processing gas supply system 10A. Thereafter, the second process gas is brought into contact with the second process gas at a high flow rate and high speed from the second process gas supply system 10B. Thereby, it can transfer to a 2nd etching process continuously from a 1st etching process. The feeding roll 23 and the take-up roll 24 function as a workpiece support section that replaces the stage-shaped support section 20. In addition, the feed roll 23 and the take-up roll 24 constitute a switching unit that selectively switches between the processing gas supply systems 10A and 10B in which the processing gas is blown to the workpiece 90.
第７実施形態
　処理ガスの流量ひいては流速の変更は２段階に限られず、３段階以上行なうことにしてもよい。第１エッチング工程でガス流量ひいては流速を２段階以上にわたって変更してもよい。第２エッチング工程でガス流量ひいては流速を２段階以上にわたって変更してもよい。 Seventh Embodiment The change of the flow rate of the processing gas and thus the flow velocity is not limited to two steps, and may be performed in three or more steps. In the first etching step, the gas flow rate and thus the flow rate may be changed over two or more stages. In the second etching step, the gas flow rate and thus the flow rate may be changed over two or more stages.
　図８は、処理ガスの流量ひいては流速を、第１エッチング工程と第２エッチング工程の全体で３段階にわたって変更する実施形態を示したものである。
　エッチング装置１は、３つの処理ガス供給系１０を備えている。これら３つの処理ガス供給系１０を互いに区別するときは、１段目（図８において左側）の処理ガス供給系１０及びその構成要素の符号にＸを付し、２段目（図８において中央）の処理ガス供給系１０及びその構成要素の符号にＹを付し、３段目（図８において右側）の処理ガス供給系１０及びその構成要素の符号にＺを付す。１段目と２段目の処理ガス供給系１０Ｘ，１０Ｙが、第１エッチング工程を実行する第１処理ガス供給系になる。最終段（３段目）の処理ガス供給系１０Ｚが、第２エッチング工程を実行する第２処理ガス供給系になる。 FIG. 8 shows an embodiment in which the flow rate of the processing gas, and hence the flow rate, is changed over three stages in the first etching process and the second etching process.
The etching apparatus 1 includes three processing gas supply systems 10. When these three process gas supply systems 10 are distinguished from each other, X is added to the reference numerals of the first stage (left side in FIG. 8) of the process gas supply system 10 and its components, and the second stage (center in FIG. 8). ) Is attached to the reference numerals of the processing gas supply system 10 and its constituent elements, and Z is attached to the reference numerals of the third stage (right side in FIG. 8) of the processing gas supply system 10 and its constituent elements. The first-stage and second-stage process gas supply systems 10X and 10Y become the first process gas supply system for executing the first etching process. The processing gas supply system 10Z at the final stage (third stage) becomes the second processing gas supply system for executing the second etching process.
　１段目の処理ガス供給系１０Ｘは、第５実施形態（図６）及び第６実施形態（図７）の第１処理ガス供給系１０Ａと同一の構成になっている。すなわち、処理ガス供給系１０Ｘには流速調節用ガス供給部６０が接続されていない。第１処理ガス供給系１０Ａから噴き出される処理ガスは、流速調節用ガス（Ｎ２）を含まず、小流量になる。 The first stage processing gas supply system 10X has the same configuration as the first processing gas supply system 10A of the fifth embodiment (FIG. 6) and the sixth embodiment (FIG. 7). That is, the flow rate adjusting gas supply unit 60 is not connected to the processing gas supply system 10X. The processing gas ejected from the first processing gas supply system 10A does not include the flow rate adjusting gas (N 2 ) and has a small flow rate.
　２段目の処理ガス供給系１０Ｙは、第５、第６実施形態（図６、図７）の第２処理ガス供給系１０Ｂと同一の構成になっており、流速調節用ガス供給部６０Ｙが常時混合モードで運転される。ただし、流速調節用ガスの混合流量は、上記第２処理ガス供給系１０Ｂの流速調節用ガスの混合流量より小さい。 The second stage processing gas supply system 10Y has the same configuration as the second processing gas supply system 10B of the fifth and sixth embodiments (FIGS. 6 and 7). It is always operated in mixed mode. However, the mixing flow rate of the flow rate adjusting gas is smaller than the mixing flow rate of the flow rate adjusting gas in the second processing gas supply system 10B.
　３段目（最終段）の処理ガス供給系１０Ｚは、第５、第６実施形態（図６、図７）の第２処理ガス供給系１０Ｂと同一の構成になっており、流速調節用ガス供給部６０Ｙが常時混合モードで運転される。流速調節用ガスの混合流量についても、上記第２処理ガス供給系１０Ｂと同じである。 The third stage (final stage) processing gas supply system 10Z has the same configuration as the second processing gas supply system 10B of the fifth and sixth embodiments (FIGS. 6 and 7), and the flow rate adjusting gas. Supply unit 60Y is always operated in the mixed mode. The mixed flow rate of the flow rate adjusting gas is also the same as that of the second processing gas supply system 10B.
　３段目の流速調節用ガス供給部６０Ｚによる流速調節用ガスの混合流量は、２段目の流速調節用ガス供給部６０Ｙによる流速調節用ガスの混合流量の好ましくは１倍～４倍であり、より好ましくは２倍～３倍である。 The mixed flow rate of the flow rate adjusting gas by the third stage flow rate adjusting gas supply unit 60Z is preferably 1 to 4 times the mixed flow rate of the flow rate adjusting gas by the second stage flow rate adjusting gas supply unit 60Y. More preferably, it is 2 to 3 times.
　したがって、後段の処理ガス供給系１０になるほど処理ガスの噴き出し流量が大きい。 Therefore, as the process gas supply system 10 in the subsequent stage is reached, the flow rate of the process gas is larger.
　３つの処理ガス供給系１０の噴出部５９が間隔を置いて一列に並べられている。これら噴出部５９の下方にローラコンベア２５が設置されている。ローラコンベア２５は、噴出部５９の配列方向に延設されている。ローラコンベア２５によって被処理物９０が１段目の噴出部５９Ｘの下方、２段目の噴出部５９Ｙの下方、３段目の噴出部５９Ｚの下方の順に搬送される。
　ローラコンベア２５は、被処理物９０の搬送手段及び支持手段を構成する。かつ、ローラコンベア２５は、処理ガスが被処理物９０に吹き付けられる処理ガス供給系１０を選択的に切り替える切替手段を構成する。
　ローラーコンベア２５の移動速度や、処理ガス供給系１０の数は、予め実験により決めておく。 The ejection portions 59 of the three processing gas supply systems 10 are arranged in a line at intervals. A roller conveyor 25 is installed below these ejection portions 59. The roller conveyor 25 is extended in the arrangement direction of the ejection parts 59. The workpiece 90 is conveyed by the roller conveyor 25 in the order below the first stage ejection part 59X, below the second stage ejection part 59Y, and below the third stage ejection part 59Z.
The roller conveyor 25 constitutes a conveying unit and a supporting unit for the workpiece 90. And the roller conveyor 25 comprises the switching means which selectively switches the process gas supply system 10 with which process gas is sprayed on the to-be-processed object 90. FIG.
The moving speed of the roller conveyor 25 and the number of processing gas supply systems 10 are determined in advance by experiments.
[第１エッチング工程]
　被処理物９０は、ローラコンベア２５による搬送に伴ない、先ず１段目の処理ガス供給系１０Ｘからの処理ガスと接触し、エッチングされる。１段目の処理ガスには流速調節用ガス（Ｎ２）が混合されておらず、被処理物９０上でのガス流速が比較的小さい。したがって、被処理物９０の表面上に必要十分な厚さの凝縮層を形成でき、シリコン９３を高エッチングレートでエッチングできる。１段目のエッチングでは、シリコン含有膜９３の表面が粗くなり凸凹の状態になる。下地の窒化シリコン膜９２は未だ露出しない。 [First etching process]
As the workpiece 90 is transported by the roller conveyor 25, it first comes into contact with the processing gas from the first stage processing gas supply system 10X and is etched. The first-stage process gas is not mixed with the flow rate adjusting gas (N 2 ), and the gas flow rate on the workpiece 90 is relatively small. Therefore, a condensed layer having a necessary and sufficient thickness can be formed on the surface of the workpiece 90, and the silicon 93 can be etched at a high etching rate. In the first-stage etching, the surface of the silicon-containing film 93 becomes rough and becomes uneven. The underlying silicon nitride film 92 is not exposed yet.
　次に、被処理物９０は、２段目の処理ガス供給系１０Ｙからの処理ガスと接触し、エッチングされる。２段目の処理ガスには流速調節用ガス（Ｎ２）が混合される。したがって、２段目の処理ガスの流量は１段目より大きく、被処理物９０上でのガス流速が１段目より大きい。これにより、被処理物９０の表面上から水分を飛散させ、被処理物９０の表面上の凝縮層の厚さを１段目のときより小さくできる。よって、シリコン含有膜９３の下地膜９２に対する選択比を大きくできる。したがって、シリコン含有膜９３の凸凹な表面の凹の部分が下地膜９２との界面に到達したとき、下地膜９２が削れるのを抑制できる。 Next, the workpiece 90 comes into contact with the processing gas from the second stage processing gas supply system 10Y and is etched. A flow rate adjusting gas (N 2 ) is mixed with the second stage processing gas. Therefore, the flow rate of the second stage processing gas is larger than that of the first stage, and the gas flow rate on the workpiece 90 is larger than that of the first stage. Thereby, moisture is scattered from the surface of the workpiece 90, and the thickness of the condensed layer on the surface of the workpiece 90 can be made smaller than in the first stage. Therefore, the selection ratio of the silicon-containing film 93 to the base film 92 can be increased. Therefore, when the concave portion of the uneven surface of the silicon-containing film 93 reaches the interface with the base film 92, the base film 92 can be prevented from being scraped.
[第２エッチング工程]
　次に、被処理物９０は、３段目（最終段）の処理ガス供給系１０Ｚからの処理ガスと接触し、エッチングされる。３段目の処理ガスには２段目（第１エッチング工程の最終段階）より多量の流速調節用ガス（Ｎ２）が混合される。したがって、３段目の処理ガスの流量は２段目より更に大きく、被処理物９０上でのガス流速が２段目より更に大きい。これにより、被処理物９０の表面上から水分を十分に飛散させることができ、被処理物９０の表面上の凝縮層の厚さを２段目のときより更に小さくできる。よって、シリコン含有膜９３の下地膜９２に対する選択比を更に大きくできる。下地膜９２のオーバーエッチング量ｄ（図２（ｄ））を十分に小さくしつつ、斑点状の残膜９３ａを確実に除去できる。 [Second etching process]
Next, the workpiece 90 comes into contact with the processing gas from the third stage (final stage) processing gas supply system 10Z and is etched. A larger amount of flow rate adjusting gas (N 2 ) is mixed with the third stage processing gas than in the second stage (the final stage of the first etching step). Therefore, the flow rate of the third stage processing gas is larger than that of the second stage, and the gas flow rate on the workpiece 90 is higher than that of the second stage. Thereby, moisture can be sufficiently scattered from the surface of the object to be processed 90, and the thickness of the condensed layer on the surface of the object to be processed 90 can be made smaller than in the second stage. Therefore, the selection ratio of the silicon-containing film 93 to the base film 92 can be further increased. The spot-like residual film 93a can be reliably removed while sufficiently reducing the overetching amount d (FIG. 2D) of the base film 92.
第８実施形態
　図９は、本発明の第８実施形態を示したものである。第８実施形態では、酸化性反応ガスを流速調節用ガスとして代用している。
　詳述すると、第８実施形態の処理ガス供給系１０は、第４実施形態（図５）と同様に、フッ素系反応ガス供給系３３と、オゾナイザー４８を有する酸化性反応ガス供給系３５とを含む。フッ素系反応ガス供給系３３には、第４実施形態と異なり、流速調節手段としての流速調節用ガス供給部６０が接続されていない。これに代えて、酸化性反応ガス供給系３５の酸素系原料供給部３４とオゾナイザー４８とを結ぶライン上に、流速調節手段として酸化性反応ガス流量調節部６１が設けられている。流量調節部６１は、流量制御弁やマスフローコントローラにて構成されている。流量調節部６１が、酸素系原料供給部３４からオゾナイザー４８に供給される酸素系原料ガス（Ｏ２）の流量を調節し、ひいては、オゾナイザー４８からの酸化性反応ガス（Ｏ２＋Ｏ３）の供給ガス流量を調節する。
　流量調節部６１をオゾナイザー４８より下流の噴出路５２に設けてもよい。 Eighth Embodiment FIG. 9 shows an eighth embodiment of the present invention. In the eighth embodiment, the oxidizing reaction gas is used as a flow rate adjusting gas.
Specifically, the processing gas supply system 10 of the eighth embodiment includes a fluorine-based reaction gas supply system 33 and an oxidizing reaction gas supply system 35 having an ozonizer 48, as in the fourth embodiment (FIG. 5). Including. Unlike the fourth embodiment, the fluorine-based reactive gas supply system 33 is not connected to a flow rate adjusting gas supply unit 60 as a flow rate adjusting means. Instead, an oxidizing reactive gas flow rate adjusting unit 61 is provided as a flow rate adjusting unit on a line connecting the oxygen-based raw material supplying unit 34 and the ozonizer 48 of the oxidizing reactive gas supply system 35. The flow rate adjusting unit 61 includes a flow rate control valve and a mass flow controller. The flow rate adjusting unit 61 adjusts the flow rate of the oxygen-based source gas (O 2 ) supplied from the oxygen-based source supply unit 34 to the ozonizer 48, and as a result, the oxidizing reaction gas (O 2 + O 3 ) from the ozonizer 48. Adjust the supply gas flow rate.
The flow rate adjusting unit 61 may be provided in the ejection path 52 downstream from the ozonizer 48.
［第１エッチング工程］
　第８実施形態の第１エッチング工程は、第３及び第４実施形態の第１エッチング工程と実質的に同じである。フッ素系反応ガス供給系３３において、加湿フッ素系原料ガス（ＣＦ４＋Ａｒ＋Ｈ２Ｏ）をプラズマ化し、フッ素系反応ガスを生成する。併行して、酸化性反応ガス供給系３５の酸素系原料供給部３４から酸素系原料ガス（Ｏ２）をオゾナイザー４８に供給し、オゾナイザー４８によって酸化性反応ガス（Ｏ２＋Ｏ３）を生成する。これらフッ素系反応ガスと酸化性反応ガスを混合して処理ガスを得る。この処理ガスを噴出部５３から噴出し、被処理物９０に接触させる。第１エッチング工程におけるフッ素系反応ガスと酸化性反応ガスの体積混合比は、例えばフッ素系反応ガス：酸化性反応ガス＝２：１～１：２程度が好ましい。 [First etching step]
The first etching process of the eighth embodiment is substantially the same as the first etching process of the third and fourth embodiments. In the fluorine-based reaction gas supply system 33, the humidified fluorine-based source gas (CF 4 + Ar + H 2 O) is turned into plasma to generate a fluorine-based reaction gas. In parallel, oxygen-based source gas (O 2 ) is supplied from the oxygen-based source supply unit 34 of the oxidizing reaction gas supply system 35 to the ozonizer 48, and the oxidizing reaction gas (O 2 + O 3 ) is generated by the ozonizer 48. . A processing gas is obtained by mixing these fluorine-based reaction gas and oxidizing reaction gas. This processing gas is ejected from the ejection part 53 and brought into contact with the workpiece 90. The volume mixing ratio of the fluorine-based reaction gas and the oxidizing reaction gas in the first etching step is preferably, for example, about fluorine-based reaction gas: oxidation reaction gas = 2: 1 to 1: 2.
［第２エッチング工程］
　第８実施形態の第２エッチング工程では、流量調節部６１によって酸素系原料ガス（Ｏ２）ひいては酸化性反応ガス（Ｏ２＋Ｏ３）の供給流量を第１エッチング工程より大きくする。フッ素系反応ガスの供給流量は、好ましくは第１エッチング工程と同じにする。第２エッチング工程におけるフッ素系反応ガスと酸化性反応ガスの混合比は、例えばフッ素系反応ガス：酸化性反応ガス ＝ ９：５～１：３程度が好ましく、１：１～１：２強程度がより好ましい。 [Second etching step]
In the second etching process of the eighth embodiment, the supply flow rate of the oxygen-based source gas (O 2 ) and, therefore, the oxidizing reaction gas (O 2 + O 3 ) is increased by the flow rate adjusting unit 61 compared to the first etching process. The supply flow rate of the fluorine-based reaction gas is preferably the same as that in the first etching step. The mixing ratio of the fluorine-based reactive gas and the oxidizing reactive gas in the second etching step is preferably, for example, fluorine-based reactive gas: oxidative reactive gas = 9: 5 to 1: 3, preferably about 1: 1 to 1: 2 strong. Is more preferable.
　酸化性反応ガスの流量を増大させることによって、処理ガス全体の流量が増大する。これにより、被処理物９０上での処理ガスの流速が増大する。したがって、被処理物９０の表面上の水分が飛散されやすくなる。よって、第１実施形態と同様に、シリコン膜９３の下地膜９２に対する選択比を大きくできる。フッ素系反応ガスについては、第１エッチング工程と同じ流量にすることにより、シリコンのエッチングレートの低下を抑制できる。この結果、シリコン残膜９３ａを良好なエッチングレートで選択的にエッチングして除去でき、かつ下地膜９２のオーバーエッチング量ｄを小さくできる。 By increasing the flow rate of the oxidizing reaction gas, the flow rate of the entire process gas increases. Thereby, the flow velocity of the processing gas on the workpiece 90 increases. Therefore, moisture on the surface of the workpiece 90 is easily scattered. Therefore, as in the first embodiment, the selection ratio of the silicon film 93 to the base film 92 can be increased. About the fluorine-type reaction gas, the fall of the etching rate of silicon | silicone can be suppressed by setting it as the same flow rate as a 1st etching process. As a result, the silicon residual film 93a can be selectively etched and removed at a good etching rate, and the overetching amount d of the base film 92 can be reduced.
　第８実施形態では、酸化性反応ガスが流速調節用ガスを兼ねるため、流速調節専用のガス（例えばＮ２）が不要である。したがって、所要のガス種を減らすことができる。 In the eighth embodiment, since the oxidizing reaction gas also serves as the flow rate adjusting gas, a gas dedicated to the flow rate adjustment (for example, N 2 ) is unnecessary. Therefore, the required gas species can be reduced.
　本発明は、上記実施形態に限定されるものではなく、当業者に自明の範囲内で種々の改変をなすことができる。
　例えば、エッチング対象のシリコン含有膜９３は、アモルファスシリコンに限られず、ポリシリコンであってもよく、単結晶シリコンでもよい。
　エッチング対象のシリコン含有膜９３は、シリコンに限られず、酸化シリコン、炭化シリコン、酸化炭化シリコン等であってもよい。
　エッチング対象のシリコン含有膜９３が酸化シリコンである場合、処理ガスが酸化性反応成分を含む必要はない。したがって、酸素系原料供給部３４を省略できる。
　エッチング対象のシリコン含有膜９３が、炭化シリコン又は酸化炭化シリコンである場合、加熱操作によりシリコンに変換でき、その後、上記実施形態と同様にしてエッチングできる。 The present invention is not limited to the above-described embodiment, and various modifications can be made within the scope obvious to those skilled in the art.
For example, the silicon-containing film 93 to be etched is not limited to amorphous silicon, but may be polysilicon or single crystal silicon.
The silicon-containing film 93 to be etched is not limited to silicon, and may be silicon oxide, silicon carbide, silicon oxide carbide, or the like.
When the silicon-containing film 93 to be etched is silicon oxide, the processing gas does not need to contain an oxidizing reaction component. Therefore, the oxygen-based raw material supply unit 34 can be omitted.
When the silicon-containing film 93 to be etched is silicon carbide or silicon oxide carbide, it can be converted into silicon by a heating operation, and then etched in the same manner as in the above embodiment.
　下地膜９２は、窒化シリコンに限られず、エッチング対象のシリコン含有膜９３とは異なる成分であればよい。
　アモルファスシリコン等のシリコンからなるシリコン含有膜９３に対し、下地膜９２が酸化シリコンであってもよい。
　エッチング対象のシリコン含有膜９３が酸化シリコンである場合、下地膜は例えば窒化シリコンであってもよい。
　エッチング対象のシリコン含有膜９３が炭化シリコンや酸化炭化シリコンである場合、下地膜９２は例えば窒化シリコン又は酸化シリコンであってもよい。 The base film 92 is not limited to silicon nitride, and may be any component different from the silicon-containing film 93 to be etched.
For the silicon-containing film 93 made of silicon such as amorphous silicon, the base film 92 may be silicon oxide.
When the silicon-containing film 93 to be etched is silicon oxide, the base film may be, for example, silicon nitride.
When the silicon-containing film 93 to be etched is silicon carbide or silicon oxide carbide, the base film 92 may be, for example, silicon nitride or silicon oxide.
　下地膜の成分等によっては、エッチングが進行するにしたがってシリコンの下地膜に対する選択比を大きくするために、被処理物９０上での処理ガス流速を小さくしてもよい。第２エッチング工程での処理ガス流速を第１エッチング工程より小さくしてもよい。処理ガス流速を小さくした後、大きくしてもよい。処理ガス流速を大きくした後、小さくしてもよい。処理ガス流速を段階的に変化させるのに限られず、連続的に変化（漸減又は漸増）させてもよい。
　流速調節用ガス供給部６０が、混合モードのとき、流速調節用ガス（Ｎ２）の混合流量を段階的または連続的に変化させてもよい。 Depending on the components of the underlying film, the processing gas flow rate on the workpiece 90 may be reduced in order to increase the selectivity of silicon to the underlying film as etching proceeds. The processing gas flow rate in the second etching step may be smaller than that in the first etching step. The processing gas flow rate may be reduced and then increased. The processing gas flow rate may be increased and then decreased. The process gas flow rate is not limited to being changed stepwise, but may be continuously changed (gradual decrease or increase).
When the flow rate adjusting gas supply unit 60 is in the mixing mode, the mixing flow rate of the flow rate adjusting gas (N 2 ) may be changed stepwise or continuously.
　流速調節手段が、処理ガスの流速を変化させるために、処理ガス供給系１０に流速調節用ガス（Ｎ２）を混合するのに代えて、又は流速調節用ガス（Ｎ２）を混合するのに加えて、フッ素系原料ガス（ＣＦ４＋Ａｒ）の流量を変化させてもよく、フッ素系原料ガス中の希釈ガス（Ａｒ）の流量を変化させてもよく、酸素系原料（Ｏ２）の流量を変化させてもよい。 Flow rate adjusting means, for changing the flow rate of the processing gas, instead of mixing the flow rate adjusting gas (N 2) to the processing gas supply system 10, or to mix the flow rate adjusting gas (N 2) In addition, the flow rate of the fluorine-based source gas (CF 4 + Ar) may be changed, the flow rate of the dilution gas (Ar) in the fluorine-based source gas may be changed, and the oxygen-based source material (O 2 ) The flow rate may be changed.
　流速調節手段が、処理ガスの流速を変化させるために、ガス流量を調節するのに代えて、又はガス流量を調節するのに加えて、噴出部５９の開口度を調節してもよい。噴出部５９と被処理物９０との間に画成されたガス路の厚さ（噴出部５９と被処理物９０との間の距離）を調節してもよい。 In order to change the flow rate of the processing gas, the flow rate adjusting means may adjust the opening degree of the ejection portion 59 instead of adjusting the gas flow rate or in addition to adjusting the gas flow rate. You may adjust the thickness (distance between the ejection part 59 and the to-be-processed object 90) of the gas path defined between the ejection part 59 and the to-be-processed object 90. FIG.
　フッ素系原料として、ＣＦ４に代えて、Ｃ２Ｆ６、Ｃ３Ｆ６、Ｃ３Ｆ８等の他のＰＦＣ（パーフルオロカーボン）を用いてもよく、ＣＨＦ３、ＣＨ２Ｆ２、ＣＨ３Ｆ等のＨＦＣ（ハイドロフルオロカーボン）を用いてもよく、ＳＦ６、ＮＦ３、ＸｅＦ２等のＰＦＣ及びＨＦＣ以外のフッ素含有化合物を用いてもよい。
　希釈ガスとして、Ａｒに代えて、Ｈｅ、Ｎｅ、Ｎ２等の他の不活性ガスを用いてもよい。
　酸素系原料として、Ｏ２に代えて、ＮＯ、ＮＯ２、Ｎ２Ｏ等の酸素含有化合物を用いてもよい。
　水（Ｈ２Ｏ）に代えて、ＯＨ基含有化合物を用いてもよい。ＯＨ基含有化合物として、過酸化水素水（Ｈ２Ｏ２）やエタノールやメタノール等のアルコールが挙げられる。ただし、過酸化水素水の場合は、反応性が高く、安定してフッ素系反応成分のガスに添加することが難しい。また、アルコールの場合は、プラズマ中に導入された際に炭素成分（Ｃ）が反応し、有機重合体が生成されるため、その分解・除去が必要になる。そのため、簡便で安定に供給できるＨ２Ｏが好ましい。 Instead of CF 4 , other PFCs (perfluorocarbons) such as C 2 F 6 , C 3 F 6 , and C 3 F 8 may be used as the fluorine-based raw material. CHF 3 , CH 2 F 2 , and CH 3 HFC (hydrofluorocarbon) such as F may be used, and fluorine-containing compounds other than PFC and HFC such as SF 6 , NF 3 , and XeF 2 may be used.
As a dilution gas, other inert gas such as He, Ne, N 2 may be used instead of Ar.
As the oxygen-based raw material, oxygen-containing compounds such as NO, NO 2 , and N 2 O may be used instead of O 2 .
Instead of water (H 2 O), an OH group-containing compound may be used. Examples of the OH group-containing compound include hydrogen peroxide water (H 2 O 2 ) and alcohols such as ethanol and methanol. However, in the case of hydrogen peroxide, the reactivity is high and it is difficult to stably add it to the gas of the fluorine-based reaction component. In the case of alcohol, the carbon component (C) reacts when it is introduced into the plasma, and an organic polymer is produced. Therefore, it is necessary to decompose and remove it. Therefore, H 2 O that can be supplied simply and stably is preferable.
　酸化性反応成分をプラズマ生成部４４又はオゾナイザー４８を用いて生成するのに代えて、Ｏ３等の酸化性反応成分そのものをタンク等に蓄えておき、このタンクから酸化性反応成分を取り出してフッ素系反応成分と混合してもよい。
　第３実施形態（図４）及び第４実施形態（図５）において、フッ素系反応ガスと酸化性反応ガスとを混合せずに互いに別の噴出部から被処理物へ向けて吹き出すようにしてもよい。 Instead of generating the oxidizing reaction component using the plasma generating unit 44 or the ozonizer 48, the oxidizing reaction component itself such as O 3 is stored in a tank or the like, and the oxidizing reaction component is taken out from the tank to remove fluorine. You may mix with a system reaction component.
In the third embodiment (FIG. 4) and the fourth embodiment (FIG. 5), the fluorine-based reaction gas and the oxidizing reaction gas are not mixed and blown out from different jetting parts toward the object to be processed. Also good.
　第１エッチング工程から第２エッチング工程に切り替えるタイミングは、下地膜９２が露出した段階に限られず、下地膜９２が露出する少し前の段階に設定してもよい。 The timing of switching from the first etching process to the second etching process is not limited to the stage where the base film 92 is exposed, and may be set to a stage just before the base film 92 is exposed.
　処理ガス供給系１０を複数設け、被処理物９０に対向する系１０を切替手段で選択的に切り替える場合、処理ガス供給系１０は２つ（第５、第６実施形態（図６、図７））又は３つ（第７実施形態（図８））に限られず、４つ以上設けてもよい。
　複数の処理ガス供給系１０のうち少なくとも２つの処理ガス供給系１０のガス流量ひいては流速が異なっていればよく、複数の処理ガス供給系１０のすべてのガス流量ひいては流速が１段ずつ異なっているのに限られず、複数（３つ以上）の処理ガス供給系１０のうち一部（２つ以上）の処理ガス供給系１０のガス流量ひいては流速が互いに同じであってもよい。 In the case where a plurality of processing gas supply systems 10 are provided and the system 10 facing the workpiece 90 is selectively switched by the switching means, there are two processing gas supply systems 10 (fifth and sixth embodiments (FIGS. 6 and 7). )) Or three (seventh embodiment (FIG. 8)), four or more may be provided.
It is only necessary that the gas flow rates of the at least two processing gas supply systems 10 among the plurality of processing gas supply systems 10 and the flow velocities be different, and all the gas flow rates and therefore the flow velocities of the plurality of processing gas supply systems 10 are different by one stage. However, the gas flow rates of the partial (two or more) processing gas supply systems 10 among the plural (three or more) processing gas supply systems 10 and the flow velocities may be the same.
　第７実施形態（図８）において、処理ガス供給系１０Ｘを２つ並設し、装置１全体で処理ガス供給系１０を４つ設けてもよい。この構造は、シリコン含有膜９３の厚さが大きく、１つの処理ガス供給系１０Ｘでエッチングできる量がシリコン含有膜９３の厚さの半分未満である場合に好適である。すなわち、処理ガス供給系１０Ｘを２つ設けることで、シリコン含有膜９３の半分以上ないしは大部分を良好なエッチングレートでエッチングできる。その後、処理ガス供給系１０Ｙでシリコンの選択比を大きくしてエッチングし、続いて処理ガス供給系１０Ｚでシリコンの選択比を更に大きくしてエッチングする。
　シリコン含有膜９３の厚さによっては、処理ガス供給系１０Ｘを３つ以上並設してもよい。
　第７実施形態（図８）において、１段目の処理ガス供給系１０Ｘにも流速調節用ガス供給部６０を設けてもよい。 In the seventh embodiment (FIG. 8), two processing gas supply systems 10X may be provided side by side, and four processing gas supply systems 10 may be provided in the entire apparatus 1. This structure is suitable when the thickness of the silicon-containing film 93 is large and the amount that can be etched by one processing gas supply system 10X is less than half the thickness of the silicon-containing film 93. That is, by providing two processing gas supply systems 10X, more than half or most of the silicon-containing film 93 can be etched at a good etching rate. Thereafter, etching is performed by increasing the silicon selection ratio in the processing gas supply system 10Y, and then etching is performed by further increasing the silicon selection ratio in the processing gas supply system 10Z.
Depending on the thickness of the silicon-containing film 93, three or more processing gas supply systems 10X may be arranged in parallel.
In the seventh embodiment (FIG. 8), the flow rate adjusting gas supply unit 60 may also be provided in the first stage process gas supply system 10X.
　複数の実施形態を互いに組み合わせてもよい。例えば、第３～第７実施形態（図４～図８）の流速調節用ガス供給部６０を、第１実施形態（図１）と同様に原料供給ライン３０に接続してもよい。
　第５～第７実施形態（図６～図８）の各処理ガス供給系１０を、第３、第４実施形態（図４、図５）と同様にフッ素系反応成分と酸化性反応成分とが互いに別ルートで生成される構成にしてもよい。
　第８実施形態（図９）において、オゾナイザー４８に代えて、第３実施形態（図４）のプラズマ生成部４４を用いてもよい。
　第１、第２実施形態（図１、図２）において、第８実施形態と同様に、流速調節用ガス供給部６０を省略し、これに代えて、酸素系原料供給部３４の原料供給ライン３０への接続路上に流量調節部６１を設け、酸素系原料ガスひいては酸化性反応成分を、流速調節用ガスとして代用してもよい。この場合、酸素系原料ガスの流量変化に伴なう、プラズマ生成部４０における放電の安定性及びフッ素系反応ガスの生成効率に対する影響に留意する。
　第５、第６実施形態（図６、図７）において、第８実施形態と同様に、処理ガス供給系１０Ｂの流速調節用ガス供給部６０Ｂを省略し、これに代えて、酸素系原料供給部３４Ｂの原料供給ライン３０Ｂへの接続路上に流量調節部６１を設け、酸素系原料ガスひいては酸化性反応成分を、流速調節用ガスとして代用してもよい。この場合、酸素系原料ガスの流量変化に伴なう、プラズマ生成部４０Ｂにおける放電の安定性及びフッ素系反応ガスの生成効率に対する影響に留意する。
　第７実施形態（図８）において、第８実施形態と同様に、処理ガス供給系１０Ｙ，１０Ｚの流速調節用ガス供給部６０Ｙ，６０Ｚを省略し、これに代えて、酸素系原料供給部３４Ｙ，３４Ｚの原料供給ライン３０Ｙ，３０Ｚへの各接続路上に流量調節部６１を設け、酸素系原料ガスひいては酸化性反応成分を、流速調節用ガスとして代用してもよい。この場合、酸素系原料ガスの流量変化に伴なう、プラズマ生成部４０Ｘ，４０Ｘの放電における安定性及びフッ素系反応ガスの生成効率に対する影響に留意する。
　第５～第７実施形態（図６～図８）の各処理ガス供給系１０を、第３、第４実施形態（図４、図５）と同様にフッ素系反応成分と酸化性反応成分とが互いに別ルートで生成される構成にし、かつ、処理ガス供給系１０Ｂ，１０Ｘ，１０Ｙについて、第８実施形態（図９）と同様に酸化性反応成分を流速調節用ガスとして代用する構成にしてもよい。この場合、酸素系原料ガスの流量変化に拘わらず、プラズマ生成部４０Ｂ，４０Ｘ，４０Ｙにおける放電の安定性を確保でき、フッ素系反応ガスの生成効率を安定させることができ、ひいてはシリコン含有膜のエッチングレートの変動を抑制できる。 A plurality of embodiments may be combined with each other. For example, the flow rate adjusting gas supply unit 60 of the third to seventh embodiments (FIGS. 4 to 8) may be connected to the raw material supply line 30 as in the first embodiment (FIG. 1).
Each of the processing gas supply systems 10 of the fifth to seventh embodiments (FIGS. 6 to 8) is similar to that of the third and fourth embodiments (FIGS. 4 and 5). May be generated by different routes.
In the eighth embodiment (FIG. 9), the plasma generator 44 of the third embodiment (FIG. 4) may be used instead of the ozonizer 48.
In the first and second embodiments (FIGS. 1 and 2), similarly to the eighth embodiment, the flow rate adjusting gas supply unit 60 is omitted, and instead, the material supply line of the oxygen-based material supply unit 34 is used. The flow rate adjusting unit 61 may be provided on the connection path to the No. 30, and the oxygen-based source gas and thus the oxidizing reaction component may be substituted for the flow rate adjusting gas. In this case, attention is paid to the influence on the stability of the discharge in the plasma generation unit 40 and the generation efficiency of the fluorine-based reaction gas due to the change in the flow rate of the oxygen-based source gas.
In the fifth and sixth embodiments (FIGS. 6 and 7), as in the eighth embodiment, the flow rate adjusting gas supply unit 60B of the processing gas supply system 10B is omitted, and instead, an oxygen-based material supply is provided. The flow rate adjusting unit 61 may be provided on the connection path of the unit 34B to the raw material supply line 30B, and the oxygen-based raw material gas, and thus the oxidizing reaction component, may be used as the flow rate adjusting gas. In this case, attention is paid to the influence on the stability of the discharge in the plasma generation unit 40B and the generation efficiency of the fluorine-based reactive gas accompanying the change in the flow rate of the oxygen-based source gas.
In the seventh embodiment (FIG. 8), similarly to the eighth embodiment, the flow rate adjusting gas supply units 60Y and 60Z of the processing gas supply systems 10Y and 10Z are omitted, and instead, the oxygen-based material supply unit 34Y. , 34Z may be provided on each connection path to the raw material supply lines 30Y, 30Z, and the oxygen-based raw material gas, and thus the oxidizing reaction component, may be substituted for the flow rate adjusting gas. In this case, attention is paid to the influence on the stability in the discharge of the plasma generation units 40X and 40X and the generation efficiency of the fluorine-based reaction gas accompanying the change in the flow rate of the oxygen-based source gas.
Each of the processing gas supply systems 10 of the fifth to seventh embodiments (FIGS. 6 to 8) is similar to that of the third and fourth embodiments (FIGS. 4 and 5). Are generated by different routes, and the processing gas supply systems 10B, 10X, and 10Y are configured to substitute the oxidizing reaction component as the flow rate adjusting gas in the same manner as in the eighth embodiment (FIG. 9). Also good. In this case, the stability of discharge in the plasma generation units 40B, 40X, and 40Y can be ensured regardless of the flow rate change of the oxygen-based source gas, and the generation efficiency of the fluorine-based reaction gas can be stabilized. Variation in etching rate can be suppressed.
　本発明のエッチング方法及びエッチング装置は、レジスト等でパターニングされた被処理物のパターンエッチングの他、被処理物の表面に付着したシリコンを含む汚染物質の除去、シリコンウェハやガラスの粗化部分の平坦化、シリコンウェハやガラスの表面又は裏面の粗化等にも応用できる。 The etching method and the etching apparatus according to the present invention are designed to remove contaminants including silicon adhering to the surface of an object to be processed, and to remove a roughened portion of a silicon wafer or glass in addition to pattern etching of an object to be processed patterned with a resist or the like. It can also be applied to planarization, roughening of the front or back surface of a silicon wafer or glass.
　実施例を説明する。本発明は、この実施例に限定されない。
　図５のエッチング装置を用い、アモルファスシリコン膜を第１エッチング工程と第２エッチング工程の２段階でエッチング処理を行なった。下地膜は窒化シリコンであり、この下地膜にアモルファスシリコンが積層されたサンプルを用いた。
　まず、第１エッチング工程を行なった。
　フッ素系原料としてＣＦ４を用いた。希釈ガスとしてＡｒを用いた。ＣＦ４をＡｒで希釈してフッ素系原料ガス（ＣＦ４＋Ａｒ）を得た。混合比は以下の通り。
　　ＣＦ４：Ａｒ＝１０：９０ Examples will be described. The present invention is not limited to this example.
Using the etching apparatus of FIG. 5, the amorphous silicon film was etched in two stages, a first etching process and a second etching process. The base film was silicon nitride, and a sample in which amorphous silicon was laminated on the base film was used.
First, the first etching process was performed.
CF 4 was used as a fluorine-based raw material. Ar was used as a dilution gas. CF 4 was diluted with Ar to obtain a fluorine-based source gas (CF 4 + Ar). The mixing ratio is as follows.
CF 4 : Ar = 10: 90
　上記のフッ素系原料ガス（ＣＦ４＋Ａｒ）に市販の水分添加装置で水分を添加した。水分量は、露点温度が１８℃になるよう制御した。
　流速調節用ガス供給部６０は停止モードとした。
　水添加後のフッ素系原料ガス（ＣＦ４＋Ａｒ＋Ｈ２Ｏ）をプラズマ生成部４０でプラズマ化し、フッ素系反応ガスを得た。プラズマ放電条件は以下のとおりである。
　　電極間間隔：　１ｍｍ
　　電極間電圧：　１２ｋＶ
　　電源周波数：　４０ｋＨｚ（パルス波）
　別途、酸素系原料ガスとしてＯ２ガスをオゾナイザー４８に導入して酸化性反応ガス（Ｏ２＋Ｏ３）を得た。酸化性反応ガスのオゾン濃度は約８％であった。
　プラズマ生成部４０からのフッ素系反応ガスとプラズマ生成部４４からの酸化性反応ガスとを混合し第１処理ガスを得た。フッ素系反応ガスと酸化性反応ガスの体積混合比は１：１とした。 Water was added to the fluorine-based source gas (CF 4 + Ar) with a commercially available water addition device. The amount of water was controlled so that the dew point temperature was 18 ° C.
The flow rate adjusting gas supply unit 60 was set to the stop mode.
The fluorine-based source gas (CF 4 + Ar + H 2 O) after the addition of water was turned into plasma by the plasma generation unit 40 to obtain a fluorine-based reaction gas. The plasma discharge conditions are as follows.
Distance between electrodes: 1mm
Voltage between electrodes: 12kV
Power frequency: 40 kHz (pulse wave)
Separately, O 2 gas as an oxygen-based source gas was introduced into the ozonizer 48 to obtain an oxidizing reaction gas (O 2 + O 3 ). The ozone concentration of the oxidizing reaction gas was about 8%.
The fluorine-based reaction gas from the plasma generation unit 40 and the oxidizing reaction gas from the plasma generation unit 44 were mixed to obtain a first processing gas. The volume mixing ratio of the fluorine-based reaction gas and the oxidizing reaction gas was 1: 1.
　被処理物９０をステージ２０に載せ、その上方に噴出部５３を配置した。噴出部５３から第１処理ガスを吹き出しながら、噴出部５３を被処理物９０の一端から他端までの間を往復するように移動（スキャン）させた。移動速度は、４ｍ／ｍｉｎとした。往方向又は復方向の片道移動をスキャン１回として、スキャンを１８回行ない、第１エッチング工程を終了した。このとき、被処理物９０の表面には、０．１～１０μｍの斑点状のアモルファスシリコン９３ａが残っていた（図２（ｂ）（ｃ）参照）。
　第１エッチング工程のアモルファスシリコン膜のエッチングレートは、１０．１ｎｍ／ｓｃａｎであり、アモルファスシリコン膜のシリコン窒化膜に対する選択比は約１．３であった。 The workpiece 90 was placed on the stage 20, and the ejection portion 53 was disposed above the workpiece. While the first processing gas was blown out from the ejection portion 53, the ejection portion 53 was moved (scanned) so as to reciprocate from one end to the other end of the workpiece 90. The moving speed was 4 m / min. The one-way movement in the forward direction or the backward direction was set as one scan, the scan was performed 18 times, and the first etching process was completed. At this time, spot-like amorphous silicon 93a having a thickness of 0.1 to 10 μm remained on the surface of the workpiece 90 (see FIGS. 2B and 2C).
The etching rate of the amorphous silicon film in the first etching step was 10.1 nm / scan, and the selectivity of the amorphous silicon film to the silicon nitride film was about 1.3.
　続いて、第２エッチング工程を行なった。第２エッチング工程では、流速調節用ガス供給部６０を混合モードにした。フッ素系反応ガスと流速調節用ガス（Ｎ２）との混合比は、フッ素系反応ガス：流速調節用ガス＝２：３とした。噴出部５３のスキャン回数は４回とした。第２エッチング工程のその他の処理条件は、第１エッチング工程と同じとした。 Subsequently, a second etching step was performed. In the second etching step, the flow rate adjusting gas supply unit 60 was set to the mixed mode. The mixing ratio of the fluorine-based reaction gas and the flow rate adjusting gas (N 2 ) was fluorine-based reaction gas: flow rate adjusting gas = 2: 3. The number of scans of the ejection part 53 was four. Other processing conditions in the second etching step were the same as those in the first etching step.
　第２エッチング工程によって残アモルファスシリコン９３ａを完全に除去することができた。
　第２エッチング工程のアモルファスシリコン膜のエッチングレートは、８．６ｎｍ／ｓｃａｎであり、アモルファスシリコン膜のシリコン窒化膜に対する選択比は、第１エッチング工程より高く、約２．３であった。したがって、下地のシリコン窒化膜９２のオーバーエッチングを小さくできることが確認された。 The remaining amorphous silicon 93a could be completely removed by the second etching process.
The etching rate of the amorphous silicon film in the second etching process was 8.6 nm / scan, and the selection ratio of the amorphous silicon film to the silicon nitride film was higher than that in the first etching process and was about 2.3. Therefore, it was confirmed that the overetching of the underlying silicon nitride film 92 can be reduced.
　流速調節用ガスの処理ガスへの混合比と、アモルファスシリコンの窒化シリコンに対する選択比との関係を調べた。実施例１と同様に、図５のエッチング装置を用いた。処理ガスの原料成分及び生成条件は実施例１と同じとした。この処理ガスに流速調節用ガスとして窒素（Ｎ２）を混合し、かつ窒素の混合流量を変化させた。アモルファスシリコン（ａ－Ｓｉ）と窒化シリコン（ＳｉＮｘ）のエッチングレートを測定し、アモルファスシリコン（ａ－Ｓｉ）の窒化シリコン（ＳｉＮｘ）に対する選択比を算出した。 The relationship between the mixing ratio of the flow rate adjusting gas to the processing gas and the selectivity of amorphous silicon to silicon nitride was investigated. As in Example 1, the etching apparatus shown in FIG. The raw material components and generation conditions of the processing gas were the same as those in Example 1. Nitrogen (N 2 ) was mixed with this processing gas as a flow rate adjusting gas, and the mixed flow rate of nitrogen was changed. The etching rate of amorphous silicon (a-Si) and silicon nitride (SiNx) was measured, and the selection ratio of amorphous silicon (a-Si) to silicon nitride (SiNx) was calculated.
　結果を図１０に示す。同図に示すように、流速調節用ガス（Ｎ２）の混合比が増大するにしたがって、アモルファスシリコン（ａ－Ｓｉ）のエッチングレートも窒化シリコン（ＳｉＮｘ）のエッチングレートも共に低下したが、窒化シリコン（ＳｉＮｘ）のほうがアモルファスシリコン（ａ－Ｓｉ）よりエッチングレートの低下度合いが大きかった。そのため、流速調節用ガス（Ｎ２）の混合比が増大するにしたがって、アモルファスシリコン（ａ－Ｓｉ）の窒化シリコン（ＳｉＮｘ）に対する選択比が増大した。この結果から、第２エッチング工程において、適宜な量の流速調節用ガスを処理ガスに混合して流速を増大させることで、窒化シリコン膜９２のオーバーエッチングを抑制できることが確認された。 The results are shown in FIG. As shown in the figure, both the etching rate of amorphous silicon (a-Si) and the etching rate of silicon nitride (SiNx) decreased as the mixing ratio of the flow rate adjusting gas (N 2 ) increased. Silicon (SiNx) had a greater decrease in the etching rate than amorphous silicon (a-Si). Therefore, the selection ratio of amorphous silicon (a-Si) to silicon nitride (SiNx) increased as the mixing ratio of the flow rate adjusting gas (N 2 ) increased. From this result, it was confirmed that overetching of the silicon nitride film 92 can be suppressed by increasing the flow rate by mixing an appropriate amount of flow rate adjusting gas with the processing gas in the second etching step.
　図９のエッチング装置を用い、流速調節用ガスを酸化性反応ガスで代用した場合の、酸化性反応ガスのフッ素系反応ガスへの混合比と、アモルファスシリコンの窒化シリコンに対する選択比との関係を調べた。
　フッ素系反応ガスの原料成分及び生成条件は実施例１と同じとした。ただし、実施例３では、実施例１と異なり、流速調節用ガスとしてのＮ２ガスを使用していない。別途、実施例１と同様に、オゾナイザー４８によってオゾン含有ガス（Ｏ２＋Ｏ３）からなる酸化性反応ガスを生成した。フッ素系反応ガスと酸化性反応ガスの体積混合比を２：１～１：２となるように酸化性反応ガスの流量を変化させた。フッ素系反応ガスの流量は一定とした。アモルファスシリコン（ａ－Ｓｉ）と窒化シリコン（ＳｉＮｘ）のエッチングレートを測定し、アモルファスシリコン（ａ－Ｓｉ）の窒化シリコン（ＳｉＮｘ）に対する選択比を算出した。 The relationship between the mixing ratio of the oxidizing reactive gas to the fluorine-based reactive gas and the selective ratio of amorphous silicon to silicon nitride when the flow rate adjusting gas is replaced with the oxidizing reactive gas using the etching apparatus of FIG. Examined.
The raw material components and production conditions of the fluorine-based reaction gas were the same as those in Example 1. However, unlike Example 1, Example 3 does not use N 2 gas as a flow rate adjusting gas. Separately, an oxidizing reaction gas composed of an ozone-containing gas (O 2 + O 3 ) was generated by the ozonizer 48 as in Example 1. The flow rate of the oxidizing reaction gas was changed so that the volume mixing ratio of the fluorine-based reaction gas and the oxidizing reaction gas was 2: 1 to 1: 2. The flow rate of the fluorine-based reaction gas was constant. The etching rate of amorphous silicon (a-Si) and silicon nitride (SiNx) was measured, and the selection ratio of amorphous silicon (a-Si) to silicon nitride (SiNx) was calculated.
　結果を図１１に示す。同図に示すように、酸化性反応ガスの混合比が増大するにしたがって、アモルファスシリコン（ａ－Ｓｉ）のエッチングレートも窒化シリコン（ＳｉＮｘ）のエッチングレートも共に低下したが、窒化シリコン（ＳｉＮｘ）のほうがアモルファスシリコン（ａ－Ｓｉ）よりエッチングレートの低下度合いが大きかった。そのため、酸化性反応ガスの混合比が増大するにしたがって、アモルファスシリコン（ａ－Ｓｉ）の窒化シリコン（ＳｉＮｘ）に対する選択比が増大した。この結果から、第２エッチング工程において、酸化性反応ガスの流量を増加させ、処理ガスの流速を増大させることで、窒化シリコン膜９２のオーバーエッチングを抑制できることが確認された。 The results are shown in FIG. As shown in the figure, as the mixing ratio of the oxidizing reaction gas increases, both the etching rate of amorphous silicon (a-Si) and the etching rate of silicon nitride (SiNx) decrease, but silicon nitride (SiNx) In this case, the rate of decrease in the etching rate was larger than that of amorphous silicon (a-Si). Therefore, as the mixing ratio of the oxidizing reaction gas increased, the selectivity ratio of amorphous silicon (a-Si) to silicon nitride (SiNx) increased. From this result, it was confirmed that the overetching of the silicon nitride film 92 can be suppressed by increasing the flow rate of the oxidizing reaction gas and increasing the flow rate of the processing gas in the second etching step.
　本発明は、例えばフラットパネルディスプレイ（ＦＰＤ）や半導体ウェハの製造に適用可能である。 The present invention is applicable, for example, to the manufacture of flat panel displays (FPD) and semiconductor wafers.

Claims (27)

  1. 　シリコン含有膜が下地膜に積層された被処理物をエッチングする方法において、
    　フッ素系反応成分を含む処理ガスを前記被処理物に接触させ、
    　前記処理ガスの被処理物上での流速をエッチングの進行に応じて変化させることを特徴とするシリコン含有膜のエッチング方法。     In a method of etching an object to be processed in which a silicon-containing film is laminated on a base film,
    A treatment gas containing a fluorine-based reaction component is brought into contact with the object to be treated;
    A method for etching a silicon-containing film, wherein the flow rate of the processing gas on the object to be processed is changed according to the progress of etching.
  2. 　前記流速をエッチングが進むにしたがって大きくすることを特徴とする請求項１に記載のエッチング方法。 The etching method according to claim 1, wherein the flow rate is increased as etching progresses.
  3. 　前記流速をエッチングが進むにしたがって段階的に大きくすることを特徴とする請求項１に記載のエッチング方法。 2. The etching method according to claim 1, wherein the flow rate is increased stepwise as etching progresses.
  4. 　前記シリコン含有膜のエッチングすべき部分の大半をエッチングする期間（以下「第１エッチング工程」と称す）の前記流速を相対的に小さくし、前記シリコン含有膜のエッチングすべき部分のうち前記第１エッチング工程後に残った部分をエッチングする期間（以下「第２エッチング工程」と称す）の前記流速を相対的に大きくすることを特徴とする請求項１に記載のエッチング方法。 The flow rate during a period in which most of the portion to be etched of the silicon-containing film is etched (hereinafter referred to as “first etching step”) is relatively reduced, and the first portion of the portion to be etched of the silicon-containing film is formed. 2. The etching method according to claim 1, wherein the flow rate during a period of etching a portion remaining after the etching step (hereinafter referred to as a “second etching step”) is relatively increased.
  5. 　前記第１エッチング工程で前記流速を段階的に大きくし、前記第２エッチング工程での前記流速を前記第１エッチング工程の最終段階より大きくすることを特徴とする請求項４に記載のエッチング方法。 5. The etching method according to claim 4, wherein the flow rate is increased stepwise in the first etching step, and the flow rate in the second etching step is made larger than the final step of the first etching step.
  6. 　前記処理ガスの流量を変化させることにより、前記流速を変化させることを特徴とする請求項１に記載のエッチング方法。 The etching method according to claim 1, wherein the flow velocity is changed by changing a flow rate of the processing gas.
  7. 　前記フッ素系反応成分が、フッ素系原料を含みＨ２Ｏ又はＯＨ基含有化合物が添加されたフッ素系原料ガスを大気圧近傍のプラズマ空間に通して生成され、
    　前記プラズマ空間より上流側で前記フッ素系原料ガスに流速調節用ガスを混合し、又は混合を停止し、この流速調節用ガスの流量によって前記流速を調節することを特徴とする請求項１に記載のエッチング方法。     The fluorine-based reaction component is generated by passing a fluorine-based raw material gas containing a fluorine-based raw material and added with a H 2 O or OH group-containing compound through a plasma space near atmospheric pressure,
    The flow rate adjusting gas is mixed with the fluorine-based source gas upstream of the plasma space, or mixing is stopped, and the flow rate is adjusted by the flow rate of the flow rate adjusting gas. Etching method.
  8. 　前記フッ素系反応成分が、フッ素系原料を含みＨ２Ｏ又はＯＨ基含有化合物が添加されたフッ素系原料ガスを大気圧近傍のプラズマ空間に通して生成され、
    　前記プラズマ空間より下流側で前記処理ガスに流速調節用ガスを混合し、又は混合を停止し、この流速調節用ガスの流量によって前記流速を調節することを特徴とする請求項１に記載のエッチング方法。     The fluorine-based reaction component is generated by passing a fluorine-based raw material gas containing a fluorine-based raw material and added with a H 2 O or OH group-containing compound through a plasma space near atmospheric pressure,
    2. The etching according to claim 1, wherein a flow rate adjusting gas is mixed with the processing gas downstream from the plasma space, or mixing is stopped, and the flow rate is adjusted by a flow rate of the flow rate adjusting gas. Method.
  9. 　前記流速調節用ガスが、不活性ガスであることを特徴とする請求項７又は８に記載のエッチング方法。 The etching method according to claim 7 or 8, wherein the flow rate adjusting gas is an inert gas.
  10. 　前記処理ガスが、酸化性反応ガスを含み、
    　前記酸化性反応ガスの流量を変化させることにより、前記処理ガスの流量を変化させ、ひいては前記流速を変化させることを特徴とする請求項６に記載のエッチング方法。     The processing gas includes an oxidizing reaction gas,
    The etching method according to claim 6, wherein the flow rate of the processing gas is changed by changing the flow rate of the oxidizing reaction gas, and thus the flow velocity is changed.
  11. 　前記流速調節用ガスが、酸化性反応ガスであることを特徴とする請求項８に記載のエッチング方法。 The etching method according to claim 8, wherein the flow rate adjusting gas is an oxidizing reaction gas.
  12. 　シリコン含有膜が下地膜に積層された被処理物をエッチングする装置において、
    　フッ素系反応成分を含む処理ガスを前記被処理物に供給する処理ガス供給系と、
    　前記処理ガスの被処理物上での流速をエッチングの進行に応じて変化させる流速調節手段と、
    　を備えたことを特徴とするシリコン含有膜のエッチング装置。     In an apparatus for etching an object to be processed in which a silicon-containing film is laminated on a base film,
    A processing gas supply system for supplying a processing gas containing a fluorine-based reaction component to the object to be processed;
    A flow rate adjusting means for changing the flow rate of the process gas on the workpiece according to the progress of etching;
    An apparatus for etching a silicon-containing film, comprising:
  13. 　前記流速調節手段が、前記流速をエッチングが進むにしたがって大きくすることを特徴とする請求項１２に記載のエッチング装置。 13. The etching apparatus according to claim 12, wherein the flow rate adjusting means increases the flow rate as etching progresses.
  14. 　前記流速調節手段が、前記流速をエッチングが進むにしたがって段階的に大きくすることを特徴とする請求項１２に記載のエッチング装置。 13. The etching apparatus according to claim 12, wherein the flow rate adjusting means increases the flow rate stepwise as etching progresses.
  15. 　前記流速調節手段が、前記シリコン含有膜のエッチングすべき部分の大半がエッチングされる迄、前記流速を相対的に小さくし、残りのシリコン含有膜をエッチングするとき、前記流速を相対的に大きくすることを特徴とする請求項１２に記載のエッチング装置。 The flow rate adjusting means reduces the flow rate relatively until most of the portion to be etched of the silicon-containing film is etched, and relatively increases the flow rate when etching the remaining silicon-containing film. The etching apparatus according to claim 12.
  16. 　前記流速調節手段が、前記処理ガスの流量を調節することを特徴とする請求項１２に記載のエッチング装置。 13. The etching apparatus according to claim 12, wherein the flow rate adjusting means adjusts the flow rate of the processing gas.
  17. 　前記処理ガス供給系が、大気圧近傍のプラズマ空間を形成するプラズマ生成部と、前記フッ素系反応成分となるフッ素系原料を含みＨ２Ｏ又はＯＨ基含有化合物が添加されたフッ素系原料ガスを前記プラズマ空間に導入する原料供給ラインと、を含み、
    　前記流速調節手段が、前記原料供給ラインに流速調節用ガスを混合し、又は混合を停止し、この流速調節用ガスの流量によって前記流速を調節することを特徴とする請求項１２に記載のエッチング装置。     The processing gas supply system includes a plasma generation unit that forms a plasma space near atmospheric pressure, and a fluorine-based source gas that includes a fluorine-based material that serves as the fluorine-based reaction component and to which an H 2 O or OH group-containing compound is added. A raw material supply line to be introduced into the plasma space,
    The etching according to claim 12, wherein the flow rate adjusting means mixes or stops mixing the flow rate adjusting gas in the raw material supply line, and adjusts the flow rate according to the flow rate of the flow rate adjusting gas. apparatus.
  18. 　前記処理ガス供給系が、大気圧近傍のプラズマ空間を形成するプラズマ生成部と、前記フッ素系反応成分となるフッ素系原料を含みＨ２Ｏ又はＯＨ基含有化合物が添加されたフッ素系原料ガスを前記プラズマ空間に導入する原料供給ラインと、を含み、
    　前記流速調節手段が、前記プラズマ空間より下流側の処理ガス供給系に流速調節用ガスを混合し、又は混合を停止し、この流速調節用ガスの流量によって前記流速を調節することを特徴とする請求項１２に記載のエッチング装置。     The processing gas supply system includes a plasma generation unit that forms a plasma space near atmospheric pressure, and a fluorine-based source gas that includes a fluorine-based material that serves as the fluorine-based reaction component and to which an H 2 O or OH group-containing compound is added. A raw material supply line to be introduced into the plasma space,
    The flow rate adjusting means mixes the flow rate adjusting gas into the processing gas supply system downstream of the plasma space or stops mixing, and adjusts the flow rate according to the flow rate of the flow rate adjusting gas. The etching apparatus according to claim 12.
  19. 　前記処理ガス供給系が、前記フッ素系反応成分を含有するフッ素系反応ガスを前記被処理物に供給するフッ素系反応ガス供給系と、酸化性反応成分を含有する酸化性反応ガスを前記被処理物に供給する酸化性反応ガス供給系とを含み、
    　前記流速調節手段が、前記酸化性反応ガス供給系の供給ガス流量を調節することを特徴とする請求項１６に記載のエッチング装置。     The process gas supply system supplies a fluorine-based reaction gas containing the fluorine-based reaction component to the object to be processed, and a fluorine-based reaction gas supply system that supplies the object to be processed, and an oxidizing reaction gas containing an oxidizing reaction component. And an oxidizing reaction gas supply system for supplying the product,
    The etching apparatus according to claim 16, wherein the flow rate adjusting means adjusts a supply gas flow rate of the oxidizing reaction gas supply system.
  20. 　シリコン含有膜が下地膜に積層された被処理物をエッチングする装置において、
    　フッ素系反応成分を含む処理ガスを噴き出す複数の処理ガス供給系と、
    　処理ガスが前記被処理物に吹き付けられる処理ガス供給系をエッチングの進行に応じて選択的に切り替える切替手段と、
    　を備え、前記複数の処理ガス供給系のうち少なくとも２つの処理ガス供給系からの処理ガスが被処理物に吹き付けられたときの被処理物上での流速が互いに異なることを特徴とするシリコン含有膜のエッチング装置。     In an apparatus for etching an object to be processed in which a silicon-containing film is laminated on a base film,
    A plurality of processing gas supply systems for blowing out a processing gas containing a fluorine-based reaction component;
    A switching means for selectively switching a processing gas supply system in which a processing gas is sprayed onto the object to be processed according to the progress of etching;
    The silicon-containing material is characterized in that flow rates on the object to be processed when processing gases from at least two of the plurality of process gas supply systems are sprayed on the object to be processed are different from each other. Film etching equipment.
  21. 　前記切替手段が、エッチングが進むにしたがって前記流速が相対的に大きい処理ガス供給系を選択することを特徴とする請求項２０に記載のエッチング装置。 21. The etching apparatus according to claim 20, wherein the switching unit selects a processing gas supply system having a relatively high flow velocity as etching progresses.
  22. 　前記切替手段が、前記シリコン含有膜のエッチングすべき部分の大半がエッチングされる迄、前記流速が相対的に小さい処理ガス供給系を選択し、残りのシリコン含有膜をエッチングするとき、前記流速が相対的に大きい処理ガス供給系を選択することを特徴とする請求項２０に記載のエッチング装置。 When the switching means selects a processing gas supply system having a relatively low flow rate until most of the portion to be etched of the silicon-containing film is etched, and when etching the remaining silicon-containing film, the flow rate is 21. The etching apparatus according to claim 20, wherein a relatively large processing gas supply system is selected.
  23. 　前記複数の処理ガス供給系のうち少なくとも２つの処理ガス供給系の処理ガスの流量が、互いに異なることを特徴とする請求項２０に記載のエッチング装置。 The etching apparatus according to claim 20, wherein the flow rates of the processing gases of at least two processing gas supply systems among the plurality of processing gas supply systems are different from each other.
  24. 　各処理ガス供給系が、大気圧近傍のプラズマ空間を形成するプラズマ生成部と、前記フッ素系反応成分となるフッ素系原料を含みＨ２Ｏ又はＯＨ基含有化合物が添加されたフッ素系原料ガスを前記プラズマ空間に導入する原料供給ラインと、を含み、
    　少なくとも１つの処理ガス供給系の原料供給ラインに流速調節用ガスを合流させる流速調節用ガス供給部が接続されていることを特徴とする請求項２０に記載のエッチング装置。     Each processing gas supply system includes a plasma generation unit that forms a plasma space near atmospheric pressure, and a fluorine-based source gas that includes a fluorine-based source material that serves as the fluorine-based reaction component and to which an H 2 O or OH group-containing compound is added. A raw material supply line to be introduced into the plasma space,
    21. The etching apparatus according to claim 20, wherein a flow rate adjusting gas supply unit for joining the flow rate adjusting gas to the raw material supply line of at least one processing gas supply system is connected.
  25. 　各処理ガス供給系が、大気圧近傍のプラズマ空間を形成するプラズマ生成部と、前記フッ素系反応成分となるフッ素系原料を含みＨ２Ｏ又はＯＨ基含有化合物が添加されたフッ素系原料ガスを前記プラズマ空間に導入する原料供給ラインと、を含み、
    　少なくとも１つの処理ガス供給系の前記プラズマ空間より下流側の処理ガス供給系に流速調節用ガスを合流させる流速調節用ガス供給部が接続されていることを特徴とする請求項２０に記載のエッチング装置。     Each processing gas supply system includes a plasma generation unit that forms a plasma space near atmospheric pressure, and a fluorine-based source gas that includes a fluorine-based source material that serves as the fluorine-based reaction component and to which an H 2 O or OH group-containing compound is added. A raw material supply line to be introduced into the plasma space,
    21. The etching according to claim 20, wherein a flow rate adjusting gas supply unit for joining the flow rate adjusting gas to the processing gas supply system downstream of the plasma space of at least one processing gas supply system is connected. apparatus.
  26. 　前記流速調節用ガスが、不活性ガスであることを特徴とする請求項１７、１８、２４、２５の何れか１項に記載のエッチング装置。 The etching apparatus according to any one of claims 17, 18, 24, and 25, wherein the flow rate adjusting gas is an inert gas.
  27. 　前記流速調節用ガスが、酸化性反応ガスであることを特徴とする請求項１７、１８、２４、２５の何れか１項に記載のエッチング装置。 The etching apparatus according to any one of claims 17, 18, 24, and 25, wherein the flow rate adjusting gas is an oxidizing reaction gas.
PCT/JP2009/054089 2008-09-25 2009-03-04 Method and apparatus for etching silicon-containing film WO2010035522A1 (en)

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