WO2016031520A1 - 被処理体をエッチングする方法 - Google Patents
被処理体をエッチングする方法 Download PDFInfo
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- WO2016031520A1 WO2016031520A1 PCT/JP2015/072378 JP2015072378W WO2016031520A1 WO 2016031520 A1 WO2016031520 A1 WO 2016031520A1 JP 2015072378 W JP2015072378 W JP 2015072378W WO 2016031520 A1 WO2016031520 A1 WO 2016031520A1
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- Prior art keywords
- gas
- multilayer film
- magnetic layer
- layer
- etching
- Prior art date
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- 238000000034 method Methods 0.000 title claims abstract description 55
- 238000005530 etching Methods 0.000 title claims abstract description 44
- 239000007789 gas Substances 0.000 claims abstract description 141
- 238000012545 processing Methods 0.000 claims abstract description 87
- 230000005291 magnetic effect Effects 0.000 claims abstract description 61
- 229910052756 noble gas Inorganic materials 0.000 claims abstract description 15
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 claims abstract description 11
- 239000001307 helium Substances 0.000 claims description 22
- 229910052734 helium Inorganic materials 0.000 claims description 22
- SWQJXJOGLNCZEY-UHFFFAOYSA-N helium atom Chemical compound [He] SWQJXJOGLNCZEY-UHFFFAOYSA-N 0.000 claims description 22
- 229910052754 neon Inorganic materials 0.000 claims description 19
- GKAOGPIIYCISHV-UHFFFAOYSA-N neon atom Chemical compound [Ne] GKAOGPIIYCISHV-UHFFFAOYSA-N 0.000 claims description 17
- VNWKTOKETHGBQD-UHFFFAOYSA-N methane Chemical compound C VNWKTOKETHGBQD-UHFFFAOYSA-N 0.000 claims description 16
- XKRFYHLGVUSROY-UHFFFAOYSA-N Argon Chemical compound [Ar] XKRFYHLGVUSROY-UHFFFAOYSA-N 0.000 claims description 10
- 229910052743 krypton Inorganic materials 0.000 claims description 10
- DNNSSWSSYDEUBZ-UHFFFAOYSA-N krypton atom Chemical compound [Kr] DNNSSWSSYDEUBZ-UHFFFAOYSA-N 0.000 claims description 9
- 229910019236 CoFeB Inorganic materials 0.000 claims description 5
- 229910052786 argon Inorganic materials 0.000 claims description 5
- 229910052724 xenon Inorganic materials 0.000 claims description 5
- FHNFHKCVQCLJFQ-UHFFFAOYSA-N xenon atom Chemical compound [Xe] FHNFHKCVQCLJFQ-UHFFFAOYSA-N 0.000 claims description 5
- 229910018979 CoPt Inorganic materials 0.000 claims 1
- 239000010408 film Substances 0.000 description 98
- 230000008569 process Effects 0.000 description 15
- 229910052715 tantalum Inorganic materials 0.000 description 11
- GUVRBAGPIYLISA-UHFFFAOYSA-N tantalum atom Chemical compound [Ta] GUVRBAGPIYLISA-UHFFFAOYSA-N 0.000 description 11
- 238000012546 transfer Methods 0.000 description 11
- 230000000052 comparative effect Effects 0.000 description 8
- 239000003507 refrigerant Substances 0.000 description 6
- 230000006870 function Effects 0.000 description 5
- 230000005415 magnetization Effects 0.000 description 5
- IGOJMROYPFZEOR-UHFFFAOYSA-N manganese platinum Chemical compound [Mn].[Pt] IGOJMROYPFZEOR-UHFFFAOYSA-N 0.000 description 5
- KJTLSVCANCCWHF-UHFFFAOYSA-N Ruthenium Chemical compound [Ru] KJTLSVCANCCWHF-UHFFFAOYSA-N 0.000 description 4
- GUBSQCSIIDQXLB-UHFFFAOYSA-N cobalt platinum Chemical compound [Co].[Pt].[Pt].[Pt] GUBSQCSIIDQXLB-UHFFFAOYSA-N 0.000 description 4
- 230000006866 deterioration Effects 0.000 description 4
- 230000000694 effects Effects 0.000 description 4
- 229910052707 ruthenium Inorganic materials 0.000 description 4
- 239000003302 ferromagnetic material Substances 0.000 description 3
- 239000001257 hydrogen Substances 0.000 description 3
- 229910052739 hydrogen Inorganic materials 0.000 description 3
- 230000007246 mechanism Effects 0.000 description 3
- 239000000758 substrate Substances 0.000 description 3
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 2
- CURLTUGMZLYLDI-UHFFFAOYSA-N Carbon dioxide Chemical compound O=C=O CURLTUGMZLYLDI-UHFFFAOYSA-N 0.000 description 2
- UGFAIRIUMAVXCW-UHFFFAOYSA-N Carbon monoxide Chemical compound [O+]#[C-] UGFAIRIUMAVXCW-UHFFFAOYSA-N 0.000 description 2
- 239000002885 antiferromagnetic material Substances 0.000 description 2
- 125000004429 atom Chemical group 0.000 description 2
- 229910002091 carbon monoxide Inorganic materials 0.000 description 2
- 239000004020 conductor Substances 0.000 description 2
- 238000010586 diagram Methods 0.000 description 2
- 230000005684 electric field Effects 0.000 description 2
- 238000011156 evaluation Methods 0.000 description 2
- -1 hydrogen ions Chemical class 0.000 description 2
- 239000012212 insulator Substances 0.000 description 2
- 150000002500 ions Chemical class 0.000 description 2
- 239000000696 magnetic material Substances 0.000 description 2
- 238000004519 manufacturing process Methods 0.000 description 2
- 238000005259 measurement Methods 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
- 238000012986 modification Methods 0.000 description 2
- 238000004544 sputter deposition Methods 0.000 description 2
- 229910052723 transition metal Inorganic materials 0.000 description 2
- 150000003624 transition metals Chemical class 0.000 description 2
- 229910052782 aluminium Inorganic materials 0.000 description 1
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 1
- 239000001569 carbon dioxide Substances 0.000 description 1
- 229910002092 carbon dioxide Inorganic materials 0.000 description 1
- 239000000919 ceramic Substances 0.000 description 1
- 230000008859 change Effects 0.000 description 1
- 238000001816 cooling Methods 0.000 description 1
- 239000000498 cooling water Substances 0.000 description 1
- 229910001873 dinitrogen Inorganic materials 0.000 description 1
- 230000005284 excitation Effects 0.000 description 1
- 238000010438 heat treatment Methods 0.000 description 1
- 125000004435 hydrogen atom Chemical group [H]* 0.000 description 1
- 238000009616 inductively coupled plasma Methods 0.000 description 1
- 238000010030 laminating Methods 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- 239000010453 quartz Substances 0.000 description 1
- 230000009467 reduction Effects 0.000 description 1
- 230000004044 response Effects 0.000 description 1
- 229910052710 silicon Inorganic materials 0.000 description 1
- 239000010703 silicon Substances 0.000 description 1
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N silicon dioxide Inorganic materials O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- 239000010409 thin film Substances 0.000 description 1
Images
Classifications
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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
- H01L21/302—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
-
- 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
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L27/00—Devices consisting of a plurality of semiconductor or other solid-state components formed in or on a common substrate
- H01L27/02—Devices consisting of a plurality of semiconductor or other solid-state components formed in or on a common substrate including semiconductor components specially adapted for rectifying, oscillating, amplifying or switching and having potential barriers; including integrated passive circuit elements having potential barriers
- H01L27/04—Devices consisting of a plurality of semiconductor or other solid-state components formed in or on a common substrate including semiconductor components specially adapted for rectifying, oscillating, amplifying or switching and having potential barriers; including integrated passive circuit elements having potential barriers the substrate being a semiconductor body
- H01L27/10—Devices consisting of a plurality of semiconductor or other solid-state components formed in or on a common substrate including semiconductor components specially adapted for rectifying, oscillating, amplifying or switching and having potential barriers; including integrated passive circuit elements having potential barriers the substrate being a semiconductor body including a plurality of individual components in a repetitive configuration
- H01L27/105—Devices consisting of a plurality of semiconductor or other solid-state components formed in or on a common substrate including semiconductor components specially adapted for rectifying, oscillating, amplifying or switching and having potential barriers; including integrated passive circuit elements having potential barriers the substrate being a semiconductor body including a plurality of individual components in a repetitive configuration including field-effect components
-
- H—ELECTRICITY
- H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
- H10N—ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
- H10N50/00—Galvanomagnetic devices
-
- H—ELECTRICITY
- H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
- H10N—ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
- H10N50/00—Galvanomagnetic devices
- H10N50/01—Manufacture or treatment
-
- H—ELECTRICITY
- H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
- H10N—ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
- H10N50/00—Galvanomagnetic devices
- H10N50/10—Magnetoresistive devices
-
- H—ELECTRICITY
- H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
- H10N—ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
- H10N50/00—Galvanomagnetic devices
- H10N50/80—Constructional details
- H10N50/85—Magnetic active materials
Definitions
- Embodiments of the present invention relate to a method for etching an object to be processed.
- an MRAM Magnetic Random Access Memory
- MTJ Magnetic Tunnel Junction
- the MRAM element includes a multilayer film composed of a difficult-to-etch material such as a transition metal or a magnetic material.
- a PtMn (platinum manganese) layer may be etched through a mask containing Ta (tantalum). It is desirable that the shape formed by this etching has high perpendicularity.
- Japanese Patent Application Laid-Open No. H10-228667 describes that plasma of an etching gas containing hydrogen gas, carbon dioxide gas, methane gas, and rare gas is generated, and the platinum manganese layer is dry-etched using the tantalum layer as a mask. In the method described in Patent Document 1, etching is performed while removing deposits formed on the surface of the platinum manganese layer by the plasma of hydrogen contained in the etching gas, so that the platinum manganese layer is processed with high perpendicularity. Is possible.
- the inventor deteriorates the electrical characteristics of the multilayer film, specifically, the MR ratio of the manufactured MRAM element. I found. The deterioration of the electrical characteristics is presumed to be caused by hydrogen ions or hydrogen atoms generated by the excitation of the etching gas damaging the junction surface of the multilayer film.
- the lower electrode and a multilayer film provided on the lower electrode are interposed between the first magnetic layer, the second magnetic layer, and the first magnetic layer and the second magnetic layer.
- a multilayer film including an insulating layer, and a method of etching a target object including the insulating film through a mask is processed.
- a plasma of a first processing gas that includes a first noble gas and a second noble gas having an atomic number larger than that of the first noble gas and does not include hydrogen gas is processed.
- the object to be processed is etched by the plasma of the first processing gas that contains the first rare gas and the second rare gas and does not contain hydrogen gas. Since the first processing gas does not contain hydrogen gas, it is possible to prevent the junction surface of the multilayer film from being damaged by hydrogen ions. As a result, it is possible to suppress deterioration of the electrical characteristics of the multilayer film. Further, the atoms of the first rare gas having a relatively small atomic number are modified so that each layer constituting the multilayer film is easily etched. The modified multilayer film can be easily etched with a second rare gas having an atomic number larger than that of the first rare gas. Therefore, in the method according to one aspect, the perpendicularity of the sidewall surface of the multilayer film after etching can be improved.
- the object to be processed is exposed to a plasma of a second processing gas containing helium and neon, and the multilayer film is etched by the step of exposing the object to be processed to the plasma of the first processing gas. This step may be further performed after the surface of the lower electrode is exposed.
- over-etching may be performed to reduce the width (CD: Critical Dimension) of the multilayer film.
- CD Critical Dimension
- over-etching it is desirable to maintain the thickness of the mask on the multilayer film. Since helium and neon contained in the second processing gas are relatively light rare gases, the etching efficiency for the mask is low.
- helium and neon plasma can etch the magnetic material constituting the multilayer film. That is, by using plasma containing helium and neon, the etching selectivity of the multilayer film to the mask can be increased. As a result, the width of the multilayer film can be reduced while maintaining the film thickness of the mask.
- the main etching gas and the over etching gas may further contain methane gas. Thereby, the perpendicularity of the multilayer film after etching can be further improved.
- the multilayer film may further include a fixed layer provided between the lower electrode and the first magnetic layer.
- the first magnetic layer and the second magnetic layer may be made of CoFeB
- the insulating layer may be made of MgO
- the fixed layer may be made of CoPt.
- the first noble gas may be helium or neon
- the second noble gas may be any one of argon, krypton, and xenon.
- the first rare gas may be helium and the second rare gas may be krypton.
- the present invention it is possible to improve the verticality of the side wall surface of the multilayer film while suppressing the deterioration of the electrical characteristics of the multilayer film.
- FIG. 1 is a flowchart showing an embodiment of a method for etching a workpiece.
- a lower electrode, a first magnetic layer, a second magnetic layer, and an insulating layer interposed between the first magnetic layer and the second magnetic layer The object to be processed including the multilayer film including is etched through the mask.
- the method MT shown in FIG. 1 includes a process ST1 and a process ST2.
- the method MT is performed using a plasma processing apparatus.
- a plasma processing apparatus that can be used to perform the method MT will be described.
- FIG. 2 is a diagram illustrating an example of a plasma processing apparatus.
- a plasma processing apparatus 10 shown in FIG. 2 is a capacitively coupled plasma processing apparatus. Note that the method MT can be performed using any plasma processing apparatus such as an inductively coupled plasma processing apparatus or a plasma processing apparatus using surface waves such as microwaves.
- the plasma processing apparatus 10 includes a processing container 12.
- the processing container 12 has a substantially cylindrical shape and defines a processing space S as its internal space.
- the plasma processing apparatus 10 includes a substantially disk-shaped base 14 in a processing container 12.
- the base 14 is provided below the processing space S.
- the base 14 is made of, for example, aluminum and constitutes a lower electrode.
- the base 14 has a function of absorbing the heat of the electrostatic chuck 50 described later in the process and cooling the electrostatic chuck 50.
- a refrigerant flow path 15 is formed inside the base 14, and a refrigerant inlet pipe and a refrigerant outlet pipe are connected to the refrigerant flow path 15.
- an appropriate refrigerant such as cooling water is circulated through the refrigerant flow path 15.
- the base 14 and the electrostatic chuck 50 are controlled to a predetermined temperature.
- the plasma processing apparatus 10 further includes a cylindrical holding portion 16 and a cylindrical support portion 17.
- the cylindrical holding portion 16 holds the base 14 in contact with the side and bottom edges of the base 14.
- the cylindrical support portion 17 extends in the vertical direction from the bottom portion of the processing container 12 and supports the base 14 via the cylindrical holding portion 16.
- the plasma processing apparatus 10 further includes a focus ring 18 placed on the upper surface of the cylindrical holder 16.
- the focus ring 18 can be made of, for example, silicon or quartz.
- an exhaust path 20 is formed between the side wall of the processing vessel 12 and the cylindrical support portion 17.
- a baffle plate 22 is attached to the inlet of the exhaust passage 20 or in the middle thereof.
- An exhaust port 24 is provided at the bottom of the exhaust path 20.
- the exhaust port 24 is defined by an exhaust pipe 28 fitted in the bottom of the processing container 12.
- An exhaust device 26 is connected to the exhaust pipe 28.
- the exhaust device 26 has a vacuum pump and can depressurize the processing space S in the processing container 12 to a predetermined degree of vacuum.
- a gate valve 30 that opens and closes the loading / unloading port of the workpiece W is attached to the side wall of the processing container 12.
- the base 14 is electrically connected to a high frequency power source 32 for ion attraction through a matching unit 34.
- the high frequency power supply 32 applies a high frequency bias power of a frequency suitable for ion attraction, for example, 400 KHz, to the lower electrode, that is, the base 14.
- the plasma processing apparatus 10 further includes a shower head 38.
- the shower head 38 is provided above the processing space S.
- the shower head 38 includes an electrode plate 40 and an electrode support 42.
- the electrode plate 40 is a conductive plate having a substantially disk shape and constitutes an upper electrode.
- a high frequency power source 35 for plasma generation is electrically connected to the electrode plate 40 via a matching unit 36.
- the high frequency power supply 35 supplies a plasma generation frequency, for example, a high frequency power of 60 MHz to the electrode plate 40.
- a high frequency electric field is formed in the space between the base 14 and the electrode plate 40, that is, the processing space S.
- the electrode plate 40 has a plurality of gas vent holes 40h.
- the electrode plate 40 is detachably supported by an electrode support 42.
- a buffer chamber 42 a is provided inside the electrode support 42.
- the plasma processing apparatus 10 further includes a gas supply unit 44, and the gas supply unit 44 is connected to the gas introduction port 25 of the buffer chamber 42 a through a gas supply conduit 46.
- the gas supply unit 44 supplies a processing gas to the processing space S.
- the gas supply unit 44 can supply a plurality of types of gases.
- the gas supply unit 44 may supply a first processing gas, a second processing gas, and methane gas.
- the first processing gas is a gas that contains the first rare gas and the second rare gas and does not contain hydrogen gas.
- the second processing gas is a gas containing helium and neon.
- the first process gas and the second process gas may further include methane.
- the electrode support 42 is formed with a plurality of holes that are respectively continuous with the plurality of gas vent holes 40h, and the plurality of holes communicate with the buffer chamber 42a. Therefore, the gas supplied from the gas supply unit 44 is supplied to the processing space S via the buffer chamber 42a and the gas vent 40h.
- a magnetic field forming mechanism 48 extending in a ring shape or concentric shape is provided on the ceiling portion of the processing container 12 of the plasma processing apparatus 10.
- the magnetic field forming mechanism 48 functions to facilitate the start of high-frequency discharge (plasma ignition) in the processing space S and maintain stable discharge.
- the electrostatic chuck 50 is provided on the upper surface of the base 14.
- the electrostatic chuck 50 includes an electrode 52 and a pair of insulating films 54a and 54b.
- the insulating films 54a and 54b are films formed of an insulator such as ceramic.
- the electrode 52 is a conductive film and is provided between the insulating film 54a and the insulating film 54b.
- a direct current power source 56 is connected to the electrode 52 via a switch SW. When a DC voltage is applied to the electrode 52 from the DC power source 56, a Coulomb force is generated, and the workpiece W is attracted and held on the electrostatic chuck 50 by the Coulomb force.
- a heater which is a heating element, is embedded inside the electrostatic chuck 50 so that the workpiece W can be heated to a predetermined temperature. The heater is connected to a heater power supply via wiring.
- the plasma processing apparatus 10 further includes gas supply lines 58 and 60 and heat transfer gas supply units 62 and 64.
- the heat transfer gas supply unit 62 is connected to a gas supply line 58.
- the gas supply line 58 extends to the upper surface of the electrostatic chuck 50 and extends in an annular shape at the central portion of the upper surface.
- the heat transfer gas supply unit 62 supplies a heat transfer gas such as He gas between the upper surface of the electrostatic chuck 50 and the workpiece W.
- the heat transfer gas supply unit 64 is connected to the gas supply line 60.
- the gas supply line 60 extends to the upper surface of the electrostatic chuck 50 and extends in an annular shape so as to surround the gas supply line 58 on the upper surface.
- the heat transfer gas supply unit 64 supplies a heat transfer gas such as He gas between the upper surface of the electrostatic chuck 50 and the workpiece W.
- the plasma processing apparatus 10 further includes a control unit 66.
- the control unit 66 is connected to the exhaust device 26, the switch SW, the high frequency power source 32, the matching unit 34, the high frequency power source 35, the matching unit 36, the gas supply unit 44, and the heat transfer gas supply units 62 and 64.
- the control unit 66 sends control signals to the exhaust device 26, the switch SW, the high frequency power supply 32, the matching unit 34, the high frequency power source 35, the matching unit 36, the gas supply unit 44, and the heat transfer gas supply units 62 and 64, respectively. To do.
- the plasma processing apparatus 10 can selectively supply the first processing gas and the second processing gas to the processing space S from the gas supply unit 44.
- a processing gas such as the first processing gas and the second processing gas
- a high-frequency electric field is formed between the electrode plate 40 and the base 14, that is, in the processing space S.
- plasma is generated. Etching of the etching target layer of the target object W is performed by the active species of the elements contained in the processing gas.
- FIG. 3 is a diagram illustrating an example of an object to be processed to which the method MT is applied.
- a workpiece W shown in FIG. 3 is a product obtained in the middle of manufacturing an MRAM element having an MTJ structure.
- the 3 includes a lower electrode 102, a multilayer film ML, an upper electrode 112, and an upper layer 114.
- the lower electrode 102 is an electrode made of a conductive material, and also functions as a base layer for laminating each layer on the upper part.
- the lower electrode 102 may have a stacked structure in which, for example, a tantalum (Ta) film, a ruthenium (Ru) film, and a tantalum film are stacked in this order.
- the multilayer film ML is provided on the lower electrode 102 and includes a fixed layer 104, a first magnetic layer 106, an insulating layer 108, and a second magnetic layer 110.
- the multilayer film ML includes an MTJ structure in which an insulator is provided between a pair of ferromagnetic materials.
- the fixed layer 104 is provided between the lower electrode 102 and the first magnetic layer 106, and is made of an antiferromagnetic material such as cobalt platinum (CoPt) or platinum manganese (PtMn).
- the fixed layer 104 functions as a pinned layer that fixes the magnetization direction of the first magnetic layer 106 by the pinning effect of the antiferromagnetic material.
- the first magnetic layer 106 is provided on the fixed layer 104 and is made of a ferromagnetic material. Due to the pinning effect of the fixed layer 104, the magnetization direction of the first magnetic layer 106 is kept constant without being affected by the external magnetic field.
- the first magnetic layer 106 is made of, for example, CoFeB.
- the insulating layer 108 is provided between the first magnetic layer 106 and the second magnetic layer 110. Since the insulating layer 108 is interposed between the first magnetic layer 106 and the second magnetic layer 110, there is a tunnel magnetoresistive effect between the first magnetic layer 106 and the second magnetic layer 110. Arise. That is, between the first magnetic layer 106 and the second magnetic layer 110, the relative relationship (parallel or antiparallel) between the magnetization direction of the first magnetic layer 106 and the magnetization direction of the second magnetic layer 110. An electrical resistance corresponding to is generated.
- the insulating layer 108 is made of, for example, MgO.
- the second magnetic layer 110 is provided on the insulating layer 108 and is made of a ferromagnetic material.
- the second magnetic layer 110 functions as a so-called free layer in which the magnetization direction follows an external magnetic field.
- the second magnetic layer 110 is made of, for example, CoFeB.
- the upper electrode 112 is an electrode made of a conductive material, and is provided on the second magnetic layer 110.
- the upper electrode 112 may have a stacked structure in which, for example, a tantalum film and a ruthenium film are sequentially stacked.
- the upper layer 114 is provided on the upper electrode 112.
- the upper layer 114 is made of, for example, tantalum.
- the multilayer film ML is etched by using a laminated structure including the upper electrode 112 and the upper layer 114 as a mask MK.
- step ST1 is performed.
- the workpiece W is exposed to the plasma of the first processing gas.
- the multilayer film ML is etched through the mask MK.
- the first processing gas is a gas that contains the first rare gas and the second rare gas and does not contain hydrogen gas.
- the second rare gas contained in the first process gas is a rare gas having an atomic number larger than the atomic number of the first rare gas.
- the first rare gas is helium (He)
- any one of neon (Ne), argon (Ar), krypton (Kr), and xenon (Xe) is used as the second rare gas. it can.
- the first rare gas is neon
- any of argon, krypton, and xenon can be used as the second rare gas.
- the first rare gas may be helium or neon
- the second rare gas may be any one of argon, krypton, and xenon.
- the first noble gas may be helium and the second noble gas may be krypton.
- the first processing gas may further include methane gas.
- step ST1 the active species of the first rare gas contained in the first processing gas is modified so that the multilayer film ML is easily etched.
- the mechanism of this modification is not necessarily clear, but the active species of the first rare gas cuts part of the molecular bonds of the multilayer film ML, thereby changing the multilayer film ML to a state where it can be easily etched. It is inferred.
- step ST1 the modified multilayer film ML is removed by the active species of the second rare gas contained in the first processing gas. Since the second rare gas is a relatively heavy rare gas atom, the multilayer film ML modified with high sputtering efficiency, that is, etching efficiency can be removed. Step ST1 is performed until the surface of the lower electrode 102 is exposed.
- the multilayer film ML can be removed with high etching efficiency, so that the perpendicularity of the multilayer film ML after the etching process can be improved.
- FIG. 4 shows an example of the object to be processed W after the multilayer film ML is etched by the process ST1.
- step ST2 is then performed.
- the workpiece W is exposed to the plasma of the second processing gas.
- the second processing gas is a gas containing helium and neon. Since helium and neon have small atomic numbers and are light rare gases, the sputtering efficiency for the mask MK, that is, the etching efficiency is low. In particular, when the upper layer 114 is made of tantalum, the etching efficiency of the upper layer 114 is very low. On the other hand, helium and neon active species can remove transition metals and magnetic substances. Therefore, in step ST2, the portion of the multilayer film ML that is not located below the mask MK can be removed while maintaining the film thickness of the mask MK.
- the width of the multilayer film ML can be reduced.
- the perpendicularity of the sidewall surface of the multilayer film ML can be improved by removing the lower portion of the sidewall surface of the multilayer film ML.
- the effectiveness of the method MT will be described based on experimental examples and comparative experimental examples, but the present invention is not limited to the following experimental examples.
- the experimental result shown below was acquired by performing the etching using the plasma processing apparatus 10 with respect to the to-be-processed object W shown in FIG.
- a multilayer film in which a tantalum film, a ruthenium film, and a tantalum film are sequentially stacked is used as the lower electrode 102.
- a CoPt film was used as the fixed layer 104.
- a CoFeB film was used as the first magnetic layer 106 and the second magnetic layer 110.
- the upper electrode 112 a multilayer film in which a tantalum film and a ruthenium film are sequentially laminated is used.
- the upper layer 114 a tantalum film was used.
- the angle ⁇ of the side wall surface of the multilayer film ML etched in Experimental Example 1 and Comparative Experimental Example 1 was measured. As shown in FIG. 5, the angle ⁇ is an angle ⁇ formed by the side wall surface of the etched multilayer film ML with respect to the surface of the lower electrode 102. The measurement results are shown below.
- the angle ⁇ of the multilayer film ML obtained in Experimental Example 1 is 83.34 °.
- FIG. 6 is a graph showing changes in the film thickness MH of the upper layer 114 and the width CD of the multilayer film ML with respect to the etching time. Specifically, in FIG. 6, the film thickness MH and the width CD at the time points when the etching time is 30 seconds, 60 seconds, and 90 seconds are measured and plotted.
- the width CD of the multilayer film ML becomes smaller as the etching time becomes longer.
- the film thickness MH of the upper layer 114 tends to be maintained even when the etching time is increased.
- the width CD is reduced by 10 nm, while the reduction of the film thickness MH is about 3 nm. From this result, it is possible to reduce the width CD of the multilayer film ML while suppressing the decrease in the film thickness of the mask MK by etching the workpiece W using the second gas containing helium and neon. was confirmed.
- the process ST2 may not be performed.
- the object to be processed to which the method MT is applied is a lower electrode and a multilayer film provided on the lower electrode.
- the first magnetic layer, the second magnetic layer, the first magnetic layer, and the second film The multilayer film including the insulating layer interposed between the magnetic layer and the magnetic layer.
- the fixed layer, the first magnetic layer, the insulating layer, and the second magnetic layer are included in the multilayer film ML.
- a thin film different from the layer may be included.
- the first processing gas includes the first rare gas and the second rare gas, and may further include any gas as long as it does not include the hydrogen gas.
- the second processing gas may further include any gas as long as it includes helium and neon.
- the multilayer film ML is etched in the process ST1 of the method MT. However, in the process ST1, both the upper electrode 112 and the multilayer film ML may be etched together using the upper layer 114 as a mask. Good.
- DESCRIPTION OF SYMBOLS 10 Plasma processing apparatus, 12 ... Processing container, 102 ... Lower electrode, 104 ... Fixed layer, 106 ... First magnetic layer, 108 ... Insulating layer, 110 ... Second magnetic layer, 112 ... Upper electrode, 114 ... Upper layer , MK ... mask, ML ... multilayer film.
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Abstract
Description
まず、方法MTの工程ST1の有効性について評価した。実験例1では、第1の処理ガスのプラズマを用いてマスクMKを介して多層膜MLをエッチングした。比較実験例1では、窒素(N2)ガス及びネオンガスのプラズマを用いてマスクMKを介して多層膜MLをエッチングした。そして、実験例1及び比較実験例1でエッチングされた多層膜MLの側壁面の垂直性を評価した。実験例1及び比較実験例1の処理条件は以下の通りとした。
・処理容器12内圧力:10mTorr(1.333Pa)
・プラズマ生成用高周波電力:200W
・高周波バイアス電力:800W
・クリプトンガスの流量:85sccm
・メタンガスの流量:15sccm
・ヘリウムガスの流量:100sccm
・被処理体温度:10℃
・処理容器12内圧力:10mTorr(1.333Pa)
・プラズマ生成用高周波電力:200W
・高周波バイアス電力:800W
・窒素ガスの流量:50sccm
・ネオンガスの流量:150sccm
・被処理体温度:10℃
・比較実験例1で得られた多層膜MLの角度:29.84°
次に、方法MTの工程ST2の有効性について評価した。実験例2では、図4に示すように、工程ST1によって多層膜MLが下部電極102の表面までエッチングされた被処理体Wに対して第2のガスのプラズマを用いてオーバーエッチングを行った。そして、エッチング時間に対する上層114の膜厚MH、及び、多層膜MLの幅CDの変化を評価した。なお、図5に示すように、膜厚MHはオーバーエッチングを行った後に残った上層114の厚みであり、幅CDはオーバーエッチングを行った後の多層膜MLの底部の幅である。実験例2が実施される前の上層114の膜厚MHは61nmであり、多層膜MLの幅CDは76nmであった。また、実験例2の処理条件は以下の通りとした。
・処理容器12内圧力:10mTorr(1.333Pa)
・プラズマ生成用高周波電力:200W
・高周波バイアス電力:800W
・メタンガスの流量:15sccm
・一酸化炭素(CO)ガスの流量:43sccm
・ネオンガスの流量:85sccm
・ヘリウムガスの流量:57sccm
・被処理体温度:10℃
Claims (8)
- 下部電極と、該下部電極上に設けられる多層膜であり、第1の磁性層、第2の磁性層、及び前記第1の磁性層と前記第2の磁性層との間に介在する絶縁層を含む該多層膜と、を含む被処理体をマスクを介してエッチングする方法であって、
第1の希ガス、及び、該第1の希ガスよりも大きい原子番号を有する第2の希ガスを含み、且つ、水素ガスを含まない第1の処理ガスのプラズマに前記被処理体を晒す工程を含む、方法。 - ヘリウム及びネオンを含む第2の処理ガスのプラズマに前記被処理体を晒す工程であり、前記第1の処理ガスのプラズマに前記被処理体を晒す工程によって、前記多層膜がエッチングされて前記下部電極の表面が露出した後に行われる、該工程を更に含む、
請求項1に記載の方法。 - 前記第1の処理ガス及び前記第2の処理ガスは、メタンガスを更に含む、
請求項2に記載の方法。 - 前記多層膜は、前記下部電極と前記第1の磁性層との間に設けられる固定層を更に含む、
請求項1~3の何れか一項に記載の方法。 - 前記第1の磁性層及び前記第2の磁性層は、CoFeBから構成され、
前記絶縁層は、MgOから構成され、
前記固定層は、CoPtから構成される、
請求項4に記載の方法。 - 前記マスクは、Taを含む、
請求項1~5の何れか一項に記載の方法。 - 前記第1の希ガスは、ヘリウム又はネオンであり、
前記第2の希ガスは、アルゴン、クリプトン、キセノンのうち何れか1つである、
請求項1~6の何れか一項に記載の方法。 - 前記第1の希ガスは、ヘリウムであり、
前記第2の希ガスは、クリプトンである、
請求項1~7の何れか一項に記載の方法。
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