CN110867373B - High-precision etching method - Google Patents
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- CN110867373B CN110867373B CN201810989180.9A CN201810989180A CN110867373B CN 110867373 B CN110867373 B CN 110867373B CN 201810989180 A CN201810989180 A CN 201810989180A CN 110867373 B CN110867373 B CN 110867373B
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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
- H01L21/30604—Chemical etching
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B82—NANOTECHNOLOGY
- B82Y—SPECIFIC USES OR APPLICATIONS OF NANOSTRUCTURES; MEASUREMENT OR ANALYSIS OF NANOSTRUCTURES; MANUFACTURE OR TREATMENT OF NANOSTRUCTURES
- B82Y40/00—Manufacture or treatment of nanostructures
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- Chemical & Material Sciences (AREA)
- General Physics & Mathematics (AREA)
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- Manufacturing & Machinery (AREA)
- Nanotechnology (AREA)
- General Chemical & Material Sciences (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Computer Hardware Design (AREA)
- Microelectronics & Electronic Packaging (AREA)
- Power Engineering (AREA)
- Crystallography & Structural Chemistry (AREA)
- Weting (AREA)
- Cleaning Or Drying Semiconductors (AREA)
Abstract
The embodiment of the invention provides an etching method, which comprises the following steps: providing a modifying layer comprising one or several atomic layer thicknesses formed on selected areas of the surface of the layer of semiconductor material using a modifying agent; and removing the modified layer. The method realizes accurate control of the etching thickness in semiconductor processing, and simultaneously improves the etching rate.
Description
Technical Field
The present invention relates generally to the field of semiconductor technology, and more particularly, to a high-precision etching method.
Background
With the ever-increasing demand for various smart electronic devices, the demand for smaller, more powerful semiconductor chips has increased, and thus has come with the demand for large-scale expansion of transistors.
Although smaller chip sizes are currently available, problems with processing accuracy still remain. For example, when processing nanowires or nanoplates, precise control of the etching process is of paramount importance. In addition, selectivity is also very important for the process of forming nanowires or nanoplates by etching. Selectivity refers to the removal of the target semiconductor material by etching while leaving the remaining semiconductor material substantially intact.
In the prior art, etching is generally realized by setting different selection ratios, and the requirement of the etching process on the selection ratio is extremely high, but due to the essential difference of the selection ratios of different materials, the requirement of intelligent electronic equipment is more and more difficult to meet.
In view of the above, there is a need for a semiconductor processing method that can improve the etching accuracy to at least partially solve the above problems.
Disclosure of Invention
In order to solve at least some of the above problems, an embodiment of the present invention provides an etching method.
According to the embodiment of the invention, the etching method comprises the following steps:
forming a modification layer with one or several atomic layer thicknesses on the selected area of the surface of the semiconductor material layer by using a modifier; and
and removing the modified layer.
In some embodiments, after removing the modifying layer, further comprising: and cleaning at least the surface from which the modified layer is removed by using a second cleaning agent.
In some embodiments, further comprising: and repeatedly performing the steps of forming the modified layer by using the modifying agent and removing the modified layer until the semiconductor material layer with the preset thickness is etched at the selected area.
In some embodiments, after forming the modified layer with the modifying agent and before removing the modified layer further comprises: and cleaning at least the surface on which the modified layer is formed with a first cleaning agent.
In some embodiments, the formation of the modification layer and the removal of the modification layer are isotropic.
In some embodiments, the modifying agent reacts with selected regions of the surface of the layer of semiconductor material, and the rate of increase in the thickness of the modified layer formed decreases with increasing time of reaction with the modifying agent, at least over a period of time.
In some embodiments, the reaction is self-limiting.
In some embodiments, the modifying agent reacts with selected regions of the surface of the layer of semiconductor material until the thickness of the modifying layer of the one or several atomic layer thicknesses reaches a saturation thickness.
In some embodiments, the modification layer formed by the reaction of the one or more atomic layers at the selected region of the surface of the layer of semiconductor material with the modifying agent prevents the selected region of the surface of the layer of semiconductor material from continuing to react with the modifying agent.
In some embodiments, the etching can be performed with an etching accuracy of 0.5nm or less.
In some embodiments, the semiconductor material layer comprises Si or SiGe.
In some embodiments, the rate of removing the modified layer formed on the SiGe surface is greater than the rate of removing the modified layer formed on the Si surface.
In some embodiments, the modification layer comprises an oxide of Si or SiGe.
In some embodiments, the modifying agent comprises a liquid or aqueous solution comprising one or a combination of ozone, potassium permanganate, potassium dichromate, nitric acid, sulfuric acid, and hydrogen peroxide, an oxygen-containing gas, or an oxygen-containing plasma.
In some embodiments, the etchant comprises hydrofluoric acid, buffered hydrofluoric acid, BOE, hydrofluoric acid vapor, halogen hydride, or vapor thereof, or the like.
In some embodiments, the first and second cleaning agents comprise a liquid of water, high purity deionized water, ethanol, acetone, isopropyl alcohol, or a combination thereof, or a gas of argon, helium, nitrogen, hydrogen, water vapor, or a combination thereof.
In some embodiments, the first and second cleaning agents comprise a mixture of a liquid of water, high purity deionized water, ethanol, acetone, isopropyl alcohol, or a combination of several thereof, and a surfactant and/or a hydrophobic coating additive.
In some embodiments, the surfactant comprises an organic alcohol, aldehyde, ester, amine, or a hydrophilic group at one end and a hydrophobic group at the other end.
In some embodiments, the hydrophobic coating additive comprises trimethylchlorosilane, (CH 3) 3 SiN(CH3) 2 Propyldimethylchlorosilane, alkyltrialkoxysilane, hexadecyltrimethoxysilane, tetraethoxysilane, 3-glycidyloxypropyltrimethoxysilane and organosilicon coupling agent R a Si(R b ) n X 3-n Wherein R is a Is C 1～24 Or a linear or branched alkyl group or an aromatic group separated from the silicon atom by 1 to 8 carbons, R b Is C 1～6 X is a hydrolysable group, n =0, 1, 2.
In some embodiments, the hydrolyzable group includes a halogen or an alkoxy group.
In some embodiments, the one terminal hydrophilic group comprises an-OH, -COOH group, and the one terminal hydrophobic group comprises a hydrocarbon group.
According to the technical scheme of the embodiment of the invention, the operations of forming the modified layer and removing the modified layer are circularly executed, so that the accurate control (less than or equal to 0.5 nm) of the etching thickness in the semiconductor processing is realized, and the etching rate is improved.
Drawings
The above and other features of the present invention will become more apparent from the following detailed description when taken in conjunction with the accompanying drawings, in which:
FIG. 1 shows a flow chart of an etching method according to an embodiment of the invention;
FIG. 2 shows a flow chart of an etching method according to another embodiment of the invention;
FIG. 3 shows a flow chart of an etching method according to a further embodiment of the invention;
fig. 4A to 4E illustrate an example of a process of an etching method according to an embodiment of the present invention;
fig. 5A to 5E show another example of the process of the etching method according to the embodiment of the present invention.
In the drawings, the same or similar structures are identified by the same or similar reference numerals.
Detailed Description
In order to make the objects, technical solutions and advantages of the present application more apparent, the present application is further described in detail below with reference to the accompanying drawings. It should be noted that the following description is intended for illustration only and is not intended to limit the present disclosure. In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present disclosure. However, it will be apparent to one of ordinary skill in the art that: these specific details need not be employed to practice the present disclosure. In other instances, well-known circuits, materials, or methods have not been described in detail in order to avoid obscuring the present disclosure.
Throughout the specification, reference to "one embodiment," "an embodiment," "one example," or "an example" means: the particular features, structures, or characteristics described in connection with the embodiment or example are included in at least one embodiment of the present disclosure. Thus, the appearances of the phrases "in one embodiment," "in an embodiment," "one example" or "an example" in various places throughout this specification are not necessarily all referring to the same embodiment or example. Furthermore, the particular features, structures, or characteristics may be combined in any suitable combination and/or sub-combination in one or more embodiments or examples. Further, those of ordinary skill in the art will appreciate that the drawings provided herein are for illustrative purposes and are not necessarily drawn to scale. As used herein, the term "and/or" includes any and all combinations of one or more of the associated listed items.
A flow chart of an etching method according to an embodiment of the invention is shown in fig. 1. As shown in fig. 1, the etching method includes the following steps:
in step S110, a modification layer with one or several atomic layer thicknesses is formed on the selected region of the surface of the semiconductor material layer using a modifier.
In particular, the semiconductor material layer to be etched may include various material layers formed on the substrate. Selected regions on the surface of the layer of semiconductor material may include particular regions to be processed to form a plurality of features. In a particular embodiment, the selected area may be an area to be processed (e.g., etched) to form a plane having a thickness. In another specific embodiment, the selected region may be a region to be formed with a recess structure or a via structure by machining (e.g., etching). However, embodiments of the present invention are not limited thereto.
In the embodiment of the invention, the modifying agent is used for reacting with the surface of the semiconductor material layer to be etched so as to modify the semiconductor, and then a modifying layer with the thickness of only one or a plurality of atomic layers is formed on the surface of the semiconductor material layer.
In one embodiment, the step of forming the modified layer on the selected region of the surface of the semiconductor material layer using the modifying agent may include reacting the selected region of the surface of the semiconductor material layer with the modifying agent to form the modified layer on the selected region of the surface of the semiconductor material layer.
In one particular embodiment, the rate of increase in the thickness of the modified layer formed during the reaction of the modifying agent with the selected region of the surface of the layer of semiconductor material decreases with increasing time of reaction with the modifying agent, at least for a period of time.
In one specific embodiment, the reaction between the modifying agent and the selected regions of the surface of the layer of semiconductor material is self-limiting, and the reaction stops until the thickness of the modified layer, which is formed to a thickness of one or more atomic layers, reaches a saturation thickness.
In one embodiment, the modifying layer is formed to cover the surface of the semiconductor material layer during the reaction of the modifying agent with the selected region of the surface of the semiconductor material layer and to prevent the selected region of the surface of the semiconductor material layer from further reacting with the modifying agent.
Further, in a specific embodiment, the formation process of the modification layer is isotropic, i.e., the reaction between the surface of the semiconductor material layer and the modifying agent occurs uniformly in all directions in which the surface of the semiconductor material layer is in contact with the modifying agent.
Further, in particular embodiments, the modifier employed may be ozone (O) -containing 3 ) Potassium permanganate (KMnO) 4 ) Potassium dichromate (K) 2 Cr 2 O 7 ) Nitric acid (HNO) 3 ) Sulfuric acid (H) 2 SO 4 ) And hydrogen peroxide (H) 2 O 2 ) The liquid or aqueous solution of one of them, or a liquid or aqueous solution of a combination of several of them, may be an oxygen-containing gas or an oxygen-containing plasma, or the like.
Next, in step S120, the modified layer is removed.
Specifically, the formed modification layer may be removed by etching.
In a specific embodiment, the specific process of removing the modification layer includes bringing the modification layer formed on the surface of the semiconductor material layer into complete contact with the etchant, and a reaction occurs between the modification layer and the etchant to remove the modification layer, and when the modification layer is completely removed, the reaction between the modification layer and the etchant is terminated.
As can be seen from the above process, the process of removing the modification layer also has a certain self-limiting property, i.e., the etching process is automatically stopped after the etchant completely reacts with the modification layer formed on the surface of the semiconductor material layer. That is, the etchant does not react with the surface of the semiconductor material layer where the modification reaction does not occur.
Furthermore, in a specific embodiment, the removal process of the modification layer, i.e. the above-mentioned etching process, is isotropic, i.e. the reaction between the modification layer formed on the surface of the semiconductor material layer and the etchant occurs uniformly in all directions.
Further, in specific embodiments, the etchant used includes hydrofluoric acid (HF), buffered hydrofluoric acid (BHF), BOE, vapor of hydrofluoric acid, halogen hydride or vapor thereof, or the like. Wherein, BOE is also a buffer etching liquid, which can be made of HF and NH 4 F is prepared by mixing the components in different proportions.
In the prior art, the oxidation rate of the one-step oxidation method is relatively fast, so the thickness of the formed modified layer is not easy to control. If special measures are additionally taken to control the oxidation to proceed slowly, the etch rate as a whole is affected, resulting in too slow an etch rate. In the present application, the reaction rate is relatively high in the initial stage of the reaction between the surface of the semiconductor material layer and the modifier, and the reaction rate is rapidly decreased as the reaction proceeds because the increase rate of the thickness of the formed modified layer is decreased as the time for the reaction with the modifier is increased. Therefore, the etching method provided by the embodiment of the invention can obviously improve the etching rate under the condition of well controlling the etching amount or thickness.
This is because the thickness of the modification layer formed is only one or several atomic layer thicknesses, and because of the self-limiting nature of the reaction, the reaction between the surface of the semiconductor material layer and the modifying agent automatically stops after the thickness of the modification layer formed on the surface of the semiconductor material layer reaches the saturation thickness. Therefore, the etching method of the embodiment of the invention can well control the etching thickness and is beneficial to more accurately controlling the etching precision.
According to the method provided by the embodiment of the invention, the surface of the semiconductor material layer can be etched with the etching precision of less than or better than 0.5 nm.
Fig. 2 shows a flow chart of an etching method according to another embodiment of the present invention, which is mainly distinguished from the etching method shown in fig. 1 in that:
on the one hand, after the formation of the modified layer and before the removal of the formed modified layer (between step S210 and step S220), step S215 is performed.
In step S215, at least the surface on which the modified layer is formed is cleaned with a first cleaning agent.
After the formation operation of the modified layer is completed, a modifier residue and/or various products in reaction may be present on the surface of the modified layer and/or the semiconductor material layer. Therefore, it is necessary to clean the formed modified layer with a cleaning agent after the formation operation of the modified layer is completed, or to simultaneously clean the surface of the semiconductor material layer other than the modified layer to remove these contaminants, reduce cross contamination between the previous and subsequent steps, and ensure the processing quality of the surface of the semiconductor material layer.
On the other hand, after the modified layer is removed (after step S220), step S230 is performed.
Step S230, cleaning at least the surface from which the modified layer is removed with a second cleaning agent.
Similarly, after the formation of the modified layer and the removal of the modified layer are sequentially completed, a modifier residue, an etchant residue, and/or various products in reaction may remain on the surface of the semiconductor material layer. Therefore, after the formation of the modified layer and the removal of the modified layer are sequentially completed, the surface of the semiconductor material layer needs to be cleaned by using a cleaning agent to remove the contaminants and ensure the processing quality of the surface of the semiconductor material layer.
In specific embodiments, the first cleaning agent and the second cleaning agent may be water, high purity deionized water, ethanol, acetone, isopropanol, or a combination thereof, or argon, helium, nitrogen, hydrogen, water vapor, or a combination thereof.
In particular embodiments, the first and second cleaning agents employed may also include mixtures of liquids such as water, high purity deionized water, ethanol, acetone, isopropyl alcohol, or combinations thereof, with surfactants and/or hydrophobic coating additives.
The surfactant may reduce the surface tension of the cleaning agent (water, high purity deionized water, ethanol, acetone, isopropanol, or the like) and the hydrophobic coating additive may reduce the affinity of the cleaning agent (water, high purity deionized water, ethanol, acetone, isopropanol, or the like) to the surface being cleaned or may achieve surface hydrophobicity, and the surfactant and/or the hydrophobic coating additive may be added to the cleaning agent (water, high purity deionized water, ethanol, acetone, isopropanol, or the like). In particular embodiments, the surfactants employed may include organic alcohols, aldehydes, esters, amines or hydrophilic groups at one end and hydrophobic groups at the other end. Specifically, the hydrophilic group at one end may include an-OH group or a-COOH group, and the hydrophobic group at one end may include a hydrocarbon group. The hydrophobic coating additives may include Trimethylchlorosilane (TMCS), TMSDMA ((CH 3) 3 SiN(CH3) 2 ) Propyldimethylchlorosilane, alkyltrialkoxysilane, hexadecyltrimethoxysilane, tetraethoxysilane, 3-glycidyloxypropyltrimethoxysilane and organosilicon coupling agent R a Si(R b ) n X 3-n Wherein R is a Is C 1～24 Or a linear or branched alkyl group or an aromatic group separated from the silicon atom by 1 to 8 carbons, R b Is C 1～6 X is a hydrolysable group, n =0, 1, 2. Hydrolyzable groups include halogen or alkoxy. When the solid surface is treated, one end of the coupling agent reacts with the surface active group, and the other end forms a monomolecular layer in an oriented arrangement towards the air side, so that the water-repellent effect is remarkable. Hydrophobic paint additiveThe additive may be a surface treatment or silanization of the surface being cleaned and the hydrophobic coating additive includes a silane agent.
Step S210 and step S220 may be performed with reference to step S110 and step S120 shown in fig. 1, and are not described herein again.
Fig. 3 shows a flow chart of an etching method according to a further embodiment of the invention.
Steps S310, S315, S320 and S330 shown in fig. 3 may correspond to steps S210, S215, S220 and S230 of the embodiment of fig. 2, respectively, so that the execution process thereof may be obtained with reference to the embodiment shown in fig. 2, and only the differences therebetween will be described here.
In this embodiment, after performing step S310, step S315, step S320, and step S330 in sequence, the method further includes:
step S340, determining whether a semiconductor material layer of a predetermined thickness has been etched at the selected region. I.e., whether a predetermined etching amount or etching thickness is reached after one or more modified layer formation and modified layer removal processes.
The process may be terminated if it is determined that a predetermined thickness of the layer of semiconductor material has been etched at the selected regions.
If the semiconductor material layer with the preset thickness is not etched at the selected area, the step S310 is returned to, and the cyclic etching process is executed until the semiconductor material layer with the preset thickness is finally judged to be etched at the selected area.
In other embodiments of the present invention, after completing a cyclic etching process, the etching amount may be estimated in advance, and the thickness may be checked only when it is estimated that a predetermined thickness is to be reached, rather than checking the thickness after each cyclic etching.
Further, in this embodiment, after the modified layer is formed with the modifier and before the formed modified layer is removed, that is, between step S310 and step S320, it is also necessary to perform:
step S315: and cleaning at least the surface on which the modified layer is formed with a first cleaning agent.
This is because the modifier and/or etchant is generally reused during the cyclic etch for the purpose of saving the modifier and/or etchant. Therefore, after the modified layer is formed, the surface of the formed modified layer is cleaned with the first cleaning agent (i.e., step S315 is performed), or the surface of the semiconductor material layer other than the modified layer may be cleaned at the same time, which can prevent the semiconductor material from bringing the modifier into the etchant used for removing the modified layer.
Similarly, in the cyclic etching process, after the modification layer is removed, the surface of the semiconductor material layer which is newly exposed is cleaned by using the second cleaning agent (i.e., step S330 is performed), so that the etchant used for removing the modification layer is reduced from being carried into the modifier which is repeatedly used by the semiconductor material.
By adding step S315 and step S330, cross contamination during semiconductor etching can be effectively prevented, process fluctuation can be prevented, and processing quality can be improved.
In particular embodiments, the first and second cleaning agents employed may include water, high purity deionized water, ethanol, acetone, or isopropanol.
In particular embodiments, the first and second cleaning agents employed may also include mixtures of liquids such as water, high purity deionized water, ethanol, acetone, isopropyl alcohol, or combinations thereof, with surfactants and/or hydrophobic coating additives.
The surfactant may reduce the surface tension of the rinsing agent (water, high purity deionized water, a liquid of ethanol, acetone, isopropanol or a combination of several thereof, etc.) and the hydrophobic coating additive may reduce the affinity of the rinsing agent (water, high purity deionized water, ethanol, acetone, isopropanol or a combination of several thereof, etc.) with the surface being rinsed or may attain surface hydrophobicity, and the surfactant and/or the hydrophobic coating additive may be added to the rinsing agent (water, high purity deionized water, ethanol, acetone, isopropanol or a combination of several thereof, liquid, etc.). In specific embodiments, tables are usedThe surfactant may comprise an organic alcohol, aldehyde, ester, amine or have a hydrophilic group at one end and a hydrophobic group at the other end. Specifically, the hydrophilic group at one end may include an-OH group or a-COOH group, and the hydrophobic group at one end may include a hydrocarbon group. The hydrophobic coating additive may include Trimethylchlorosilane (TMCS), TMSDMA ((CH 3) 3 SiN(CH3) 2 ) Dimethyldichlorosilane, propyldimethylchlorosilane, alkyltrialkoxysilane, hexadecyltrimethoxysilane and tetraethoxysilane, 3-glycidoxypropyltrimethoxysilane and organosilicon coupling agent R a Si(R b ) n X 3-n Wherein R is a Is C 1～24 Or a linear or branched alkyl group or an aromatic group separated from the silicon atom by 1 to 8 carbons, R b Is C 1～6 X is a hydrolysable group, n =0, 1, 2. The hydrolyzable group includes a halogen or an alkoxy group. When the solid surface is treated, one end of the coupling agent reacts with the surface active group, and the other end forms a monomolecular layer in an oriented arrangement towards the air side, so that the water-repellent effect is remarkable. The hydrophobic coating additive may be a surface treatment or silanization treatment of the surface being cleaned, the hydrophobic coating additive including a silane agent.
According to the technical scheme of the embodiment of the invention, the operation of forming the modified layer and removing the modified layer is executed circularly, so that the accurate control of the etching thickness in the semiconductor processing is realized.
Next, the etching method and the etching effect of the present invention will be described in more detail with reference to specific examples according to embodiments of the present invention shown in fig. 4A to 4E and fig. 5A to 5E.
Referring to fig. 4A to 4E, there are shown examples of processes of an etching method according to an embodiment of the present invention. More specifically, fig. 4A to 4E show examples in which the surface of the semiconductor material layer to be etched is an exposed Si surface or SiGe surface.
As shown in fig. 4A, a substrate having a patterned exposed Si surface (or SiGe surface) 41 is first provided. In addition, a nitride layer 42 is also provided on the Si surface (or SiGe surface) 41.
Next, as shown in fig. 4B, the entire substrate is put into the surface modifier 43. The modifier 43 used may be one containing ozone (O) 3 ) Potassium permanganate (KMnO) 4 ) Potassium dichromate (K) 2 Cr 2 O 7 ) Nitric acid (HNO) 3 ) Sulfuric acid (H) 2 SO 4 ) And hydrogen peroxide (H) 2 O 2 ) The liquid or aqueous solution of one of them, or a liquid or aqueous solution of a combination of several of them, may be an oxygen-containing gas or an oxygen-containing plasma, or the like.
Since the surface of Si (or SiGe) except the uppermost surface covered with the nitrided layer 42 is completely in contact with the modifying agent 43, the surface reacts with the modifying agent 43 to consume a certain amount of Si (or SiGe) and form a thin modified layer 40 on the surface. The modification layer may in particular be an oxide of Si (or SiGe) of one or several atomic layer thicknesses, for example.
Since the uppermost surface of Si (or SiGe) is covered with the nitride layer 42, contact with the modifier 43 is avoided, and thus, the modified layer 40 is not formed on the uppermost surface of Si (or SiGe).
When the thickness of the modification layer formed on the exposed surface of Si (or SiGe) reaches the saturation thickness, the reaction between the exposed surface of Si (or SiGe) and the modifier 43 is terminated.
Next, the surface after the reaction needs to be cleaned with the first cleaning agent.
Preferably, the surface of the formed modified layer can be cleaned by using a cleaning agent such as water, high-purity deionized water, acetone or a liquid of a combination of several of the above, or argon, helium, nitrogen, hydrogen, water vapor or a gas of a combination of several of the above. This prevents the modifier from remaining, as shown in FIG. 4C. Preferably, a surfactant and/or a hydrophobic coating additive may also be added to the cleaning agent (water, high purity deionized water, ethanol, acetone, or isopropanol, or a combination thereof, or the like) in order to reduce the surface tension of the cleaning agent (water, high purity deionized water, ethanol, acetone, or isopropanol, or a combination thereof, or the like) and/or the affinity of the cleaning agent to the surface being cleanedCombined liquid), the surface of the formed modified layer is cleaned. The surfactants used may include organic alcohols, aldehydes, esters, amines or hydrophobic groups on one end and on the other. Specifically, one end having a hydrophilic group may include an-OH, -COOH group, and one end having a hydrophobic group may include a hydrocarbon group. The hydrophobic coating additive may reduce the affinity of the cleaning agent (liquid of water, high purity deionized water, ethanol, acetone, or isopropyl alcohol, or a combination thereof) for the surface being cleaned or may achieve surface hydrophobicity, and the surfactant and/or the hydrophobic coating additive may be added to the cleaning agent (liquid of water, high purity deionized water, ethanol, acetone, or isopropyl alcohol, or a combination thereof). In particular embodiments, the surfactants employed may include organic alcohols, aldehydes, esters, amines or hydrophobic groups on one end and a hydrophilic group on the other. Specifically, the hydrophilic group at one end may include an-OH group or a-COOH group, and the hydrophobic group at one end may include a hydrocarbon group. The hydrophobic coating additive may include Trimethylchlorosilane (TMCS), TMSDMA ((CH 3) 3 SiN(CH3) 2 ) Dimethyldichlorosilane, propyldimethylchlorosilane, alkyltrialkoxysilane, hexadecyltrimethoxysilane and tetraethoxysilane, 3-glycidoxypropyltrimethoxysilane and organosilicon coupling agent R a Si(R b ) n X 3-n Wherein R is a Is C 1～24 Or a linear or branched alkyl group or an aromatic group separated from the silicon atom by 1 to 8 carbons, R b Is C 1～6 X is a hydrolysable group, n =0, 1, 2. The hydrolyzable group includes a halogen or an alkoxy group. When the solid surface is treated, one end of the coupling agent reacts with the surface active group, and the other end forms a monomolecular layer which is directionally arranged towards the air side, so that the water-repellent effect is remarkable. The hydrophobic coating additive may be a surface treatment or silanization treatment of the surface being cleaned, the hydrophobic coating additive including a silane agent.
Then, the cleaned Si (or SiGe) on which the modified layer 40 is formed is etched using an etchant to remove the modified layer 40. The etchant used may be hydrofluoric acid (HF), buffered hydrofluoric acid (BHF), BOE, hydrofluoric acid vapor, halogen hydride, or vapor thereof, or the like. After the etching is completed, the originally exposed surface of Si (or SiGe) is reduced or partially etched by the formation of the modification layer and is etched away, while the uppermost surface of Si (or SiGe) covered with the nitride layer 42 is not etched, as shown in fig. 4D.
Preferably, after the etching process is finished, the surface of the semiconductor material layer is cleaned by using a second cleaning agent to remove the etchant residues and/or various product residues in the reaction, so as to prevent cross contamination. Preferably, the semiconductor surface can be cleaned with a liquid comprising water, high purity deionized water, ethanol, acetone, isopropanol, or a combination thereof, or a gas comprising argon, helium, nitrogen, hydrogen, water vapor, or a combination thereof, or the like. Preferably, in order to reduce the surface tension of the cleaning agent (water, high purity deionized water, ethanol, acetone, isopropanol or liquid of combination of the water, the high purity deionized water, the ethanol, the acetone, the isopropanol or liquid of combination of the water, the high purity deionized water, the ethanol, the isopropanol or liquid of combination of the acetone, the isopropanol or liquid of combination of the water, the high purity deionized water, the ethanol, the acetone, the isopropanol or liquid of combination of the isopropanol) and the hydrophobic coating additive can also add a surfactant into the cleaning agent to clean the semiconductor surface. The surfactants used may include organic alcohols, aldehydes, esters, amines or have a hydrophilic group at one end and a hydrophobic group at the other end. Specifically, the hydrophilic group at one end may include an-OH group or a-COOH group, and the hydrophobic group at one end may include a hydrocarbon group. The hydrophobic coating additive may reduce the affinity of the cleaning agent (water, high purity deionized water, liquids of ethanol, acetone, isopropanol, or combinations thereof, etc.) for the surface being cleaned or may achieve surface hydrophobicity, and the surfactant and/or the hydrophobic coating additive may be added to the cleaning agent (water, liquids of high purity deionized water, ethanol, acetone, isopropanol, or combinations thereof, etc.). In particular embodiments, the surfactants employed may include organic alcohols, aldehydes, esters, amines or hydrophobic groups on one end and a hydrophilic group on the other. Specifically, the hydrophilic group at one end may include an-OH group or a-COOH group, and the hydrophobic group at one end may include a hydrocarbon group. The hydrophobic coating additive may be packagedIncluding Trimethylchlorosilane (TMCS), TMSDMA ((CH 3) 3 SiN(CH3) 2 ) Dimethyldichlorosilane, propyldimethylchlorosilane, alkyltrialkoxysilane, hexadecyltrimethoxysilane, tetraethoxysilane, 3-glycidyloxypropyltrimethoxysilane and organosilicon coupling agent R a Si(R b ) n X 3-n Wherein R is a Is C 1～24 Or a linear or branched alkyl group or an aromatic group separated from the silicon atom by 1 to 8 carbons, R b Is C 1～6 X is a hydrolysable group, n =0, 1, 2. The hydrolyzable group includes a halogen or an alkoxy group. When the solid surface is treated, one end of the coupling agent reacts with the surface active group, and the other end forms a monomolecular layer in an oriented arrangement towards the air side, so that the water-repellent effect is remarkable. The hydrophobic coating additive may be a surface treatment or silanization treatment of the surface being cleaned, the hydrophobic coating additive including a silane agent.
Finally, it is determined whether the exposed surface of Si (or SiGe) has been etched to a predetermined thickness, and if not, with reference to fig. 4B to 4D, the operations of forming the modified layer and removing the modified layer are repeatedly performed until the predetermined etching thickness is reached, as shown in fig. 4E.
It can be seen that in this example, by forming the modification layer multiple times and etching the modification layer multiple times, selective etching of portions of the Si (or SiGe) surface, i.e., the exposed Si (or SiGe) surface, is achieved.
Referring to fig. 5A to 5E, there is shown another example of a process of the etching method according to the embodiment of the present invention. More specifically, fig. 5A to 5E show examples in which the surface of the semiconductor material layer to be processed is a partial surface (exposed surface) having the SiGe layer.
As shown in fig. 5A, first, an Si layer 51, an SiGe layer 52 and an Si layer 53 having a patterned exposed surface are formed on an Si substrate. SiGe layer 52 and Si layer 53 may be formed by first depositing and then patterning by epitaxial growth or CVD. As can be seen, the semiconductor structure has both an exposed Si surface and a SiGe surface.
Next, the substrate is finishedThe body is placed in a surface modifier 54. The modifier 54 employed may be ozone (O) -containing 3 ) Potassium permanganate (KMnO) 4 ) Potassium dichromate (K) 2 Cr 2 O 7 ) Nitric acid (HNO) 3 ) Sulfuric acid (H) 2 SO 4 ) And hydrogen peroxide (H) 2 O 2 ) The liquid or aqueous solution of one of them, or a liquid or aqueous solution of a combination of several of them, may also be an oxygen-containing gas or an oxygen-containing plasma, etc., as shown in fig. 5B.
Due to the action of the modifier, a modification layer 50 will be formed simultaneously on the exposed Si surface and on the SiGe surface, which modification layer 50 may in particular be an oxide of Si or an oxide of SiGe (e.g. SiGeO) at one or several atomic layer thicknesses.
Next, the reacted surface may optionally be cleaned with a first cleaning agent.
Preferably, the surface of the modified layer formed may be cleaned with a cleaning agent such as water, high-purity deionized water, ethanol, acetone, isopropyl alcohol, or a liquid containing a combination of these, or a gas containing argon, helium, nitrogen, hydrogen, water vapor, or a combination of these. This prevents the modifier from remaining, as shown in FIG. 5C. Preferably, at least the surface of the formed modified layer may also be cleaned with a first cleaning agent (water, a liquid of high purity deionized water, ethanol, acetone, isopropyl alcohol, or a combination of several thereof, etc.) comprising a surfactant and/or a hydrophobic coating additive. The surfactant can reduce the surface tension of the first cleaning agent (water, high-purity deionized water, ethanol, acetone, isopropanol or liquid of combination of the water, the high-purity deionized water, the ethanol, the acetone and the isopropanol) and/or the affinity of the first cleaning agent and the surface of the modified layer, and the surfactant can comprise organic alcohol, aldehyde, ester and amine or a hydrophilic group at one end and a hydrophobic group at the other end. Specifically, one end having a hydrophilic group may include an-OH, -COOH group, and one end having a hydrophobic group may include a hydrocarbon group. The hydrophobic coating additive can reduce the affinity of the cleaning agent (water, high purity deionized water, ethanol, acetone, isopropanol or liquid of combination of several of them, etc.) with the surface to be cleaned or can obtain surface hydrophobicity, canTo add surfactant and/or hydrophobic coating additives to the cleaning agent (water, high purity deionized water, liquids of ethanol, acetone, isopropyl alcohol, or combinations of several of these, etc.). In particular embodiments, the surfactants employed may include organic alcohols, aldehydes, esters, amines or hydrophobic groups on one end and a hydrophilic group on the other. Specifically, the hydrophilic group at one end may include an-OH group or a-COOH group, and the hydrophobic group at one end may include a hydrocarbon group. The hydrophobic coating additives may include Trimethylchlorosilane (TMCS), TMSDMA ((CH 3) 3 SiN(CH3) 2 ) Dimethyldichlorosilane, propyldimethylchlorosilane, alkyltrialkoxysilane, hexadecyltrimethoxysilane, tetraethoxysilane, 3-glycidyloxypropyltrimethoxysilane and organosilicon coupling agent R a Si(R b ) n X 3-n Wherein R is a Is C 1～24 Or a linear or branched alkyl group or an aromatic group separated from the silicon atom by 1 to 8 carbons, R b Is C 1～6 X is a hydrolysable group, n =0, 1, 2. The hydrolyzable group includes a halogen or an alkoxy group. When the solid surface is treated, one end of the coupling agent reacts with the surface active group, and the other end forms a monomolecular layer which is directionally arranged towards the air side, so that the water-repellent effect is remarkable. The hydrophobic coating additive may be a surface treatment or silanization treatment of the surface being cleaned, the hydrophobic coating additive including a silane agent.
Then, the modified layer 50 is etched with an etchant to remove the modified layer 50. The etchant used may be hydrofluoric acid (HF), buffered hydrofluoric acid (BHF), BOE, hydrofluoric acid vapor, halogen hydride, or vapor thereof, or the like.
Note that in this example, selective etching of SiGe can be achieved, as shown in fig. 5D and 5E. The originally exposed Si surface is hardly etched away, or only a small amount is etched away, revealing its surface, whereas the exposed SiGe surface is significantly reduced by a certain thickness due to the high etch rate.
In the formation stage of the modified layer, the formation rate of the modified layer on the SiGe surface can be made greater than the formation rate of the modified layer on the Si surface by using a specific modifier and appropriate process control (e.g., reaction temperature 5C to 90C and/or reaction time 1 second to 200 seconds). Therefore, the thickness of the modified layer formed on the SiGe surface will be greater than the thickness of the modified layer formed on the Si surface within the same reaction time. In other words, the number of Si and Ge atoms consumed to form the modified layer on the SiGe surface is larger than the number of Si atoms consumed on the Si surface. Thus, after etching the formed modified layer, the SiGe layer 52 is etched more, and the Si layer 51 and the Si layer 53 are etched relatively less, as shown in fig. 5D and 5E. Thereby achieving selective etching of SiGe.
More specifically, the rate of increase in the thickness of the modified layer increases with increasing temperature of the modifying agent, with the ozone (O) contained in the modifying agent 3 ) Potassium permanganate (KMnO) 4 ) Potassium dichromate (K) 2 Cr 2 O 7 ) Nitric acid (HNO) 3 ) Sulfuric acid (H) 2 SO 4 ) And hydrogen peroxide (H) 2 O 2 ) Can be increased by the increase of the concentration of (b), and the reaction rate can be accelerated or the growth rate of the modified layer can be increased by the stirring of the modifier.
On the other hand, in the formation stage of the modified layer, although there may be a problem that the formation rate of the modified layer of the SiGe surface is different from that of the modified layer of the Si surface, if the difference in thickness of the modified layers formed is not so large, it may be selected to achieve selective etching of SiGe in the process of removing the modified layer.
Specifically, in the etching stage of the modified layer, the etching rate of the modified layer formed on the SiGe surface is made greater than that of the modified layer formed on the Si surface by using a specific etchant and appropriate process control (e.g., etching temperature 5C to 80C and/or etching time 2 seconds to 120 seconds). Thus, the modified layer formed on the SiGe surface is etched to completion, and when the SiGe surface is re-exposed, the modified layer formed on the Si surface may not yet have been etched. In other examples, the modified layer formed on the Si surface may be etched away only a small portion or may not be etched. Thus, the modified layer formed on the Si surface can be used as a protective layer structure to protect the Si surface in the subsequent cyclic etching process. And the SiGe is gradually etched through the subsequent cyclic etching process, and finally the selective etching of the SiGe is realized.
Instead of effecting selective etching based primarily on the formation stage of the modification layer, effecting selective etching based on the formation stage of the modification layer requires a material (e.g., siGe) to be selectively etched, which must be formed to a thickness or amount of material that consumes selective etching greater than the thickness or amount of material that is not selected (e.g., si) to be modified, as shown in fig. 5B and 5C. The selective etching based on the removal stage of the modified layer does not require a difference in the thickness of the modified layer therebetween.
In addition, different etch rates of SiGe and Si can be achieved by adjusting the Ge content in SiGe, so to obtain good etch selectivity when it is desired to etch SiGe faster than Si, the Ge content in SiGe is preferably greater than 10% (Ge% > 10%).
In this example, it is also included to determine whether the exposed surface of the SiGe has been etched to a predetermined thickness, and in the event that the predetermined thickness is not reached, the predetermined etch thickness is achieved by a cyclical etch. Next, the reacted surface may optionally be cleaned with a second cleaning agent. Preferably, the surface of the formed modified layer may be cleaned with a cleaning agent such as water, high purity deionized water, ethanol, acetone, isopropanol, or a liquid of a combination of several of them, or a gas of argon, helium, nitrogen, hydrogen, water vapor, or a combination of several of them. Preferably, at least the surface of the formed modified layer may also be cleaned with a second cleaning agent (a liquid of water, high purity deionized water, ethanol, acetone, isopropyl alcohol, or a combination of several thereof) comprising a surfactant and/or a hydrophobic coating additive. The surfactant can reduce the surface tension of the second cleaning agent (water, high purity deionized water, ethanol, acetone, isopropanol or their combination liquid) and/or the affinity of the cleaning agent with Si or SiGe surface, and comprises organic alcohol, aldehyde, ester, amine or hydrophilic group at one end and other groupsOne end has a hydrophobic group. Specifically, one end having a hydrophilic group may include an-OH, -COOH group, and one end having a hydrophobic group may include a hydrocarbon group. The hydrophobic coating additive may reduce the affinity of the cleaning agent (water, high purity deionized water, liquids of ethanol, acetone, isopropyl alcohol, or combinations thereof, etc.) for the surface being cleaned or may achieve surface hydrophobicity, and the surfactant and/or the hydrophobic coating additive may be added to the cleaning agent (liquids of water, high purity deionized water, ethanol, acetone, isopropyl alcohol, or combinations thereof, etc.). In particular embodiments, the surfactants employed may include organic alcohols, aldehydes, esters, amines or hydrophilic groups at one end and hydrophobic groups at the other end. Specifically, one end having a hydrophilic group may include an-OH, -COOH group, and one end having a hydrophobic group may include a hydrocarbon group. The hydrophobic coating additives may include Trimethylchlorosilane (TMCS), TMSDMA ((CH 3) 3 SiN(CH3) 2 ) Dimethyldichlorosilane, propyldimethylchlorosilane, alkyltrialkoxysilane, hexadecyltrimethoxysilane and tetraethoxysilane, 3-glycidoxypropyltrimethoxysilane and organosilicon coupling agent R a Si(R b ) n X 3-n Wherein R is a Is C 1～24 Or a linear or branched alkyl group or an aromatic group separated from the silicon atom by 1 to 8 carbons, R b Is C 1～6 X is a hydrolysable group, n =0, 1, 2. The hydrolyzable group includes halogen or alkoxy. When the solid surface is treated, one end of the coupling agent reacts with the surface active group, and the other end forms a monomolecular layer in an oriented arrangement towards the air side, so that the water-repellent effect is remarkable. The hydrophobic coating additive may be a surface treatment or silanization treatment of the surface being cleaned, the hydrophobic coating additive including a silane agent. This prevents the modifier from remaining, as shown in FIG. 5C. The above embodiments and specific examples may be specifically implemented, and are not described herein again.
It can be seen that in this example, selective etching of the SiGe surface, i.e., the exposed SiGe surface, is achieved by forming the modification layer multiple times and etching the modification layer multiple times, based on the modification layer being formed on the SiGe surface at a rate greater than the modification layer being formed on the Si surface, or the modification layer being formed on the SiGe surface being removed at a rate greater than the modification layer being formed on the Si surface, in the case where both the Si surface and the SiGe surface are exposed.
Those skilled in the art will appreciate that the methods illustrated above are exemplary only. The method of the present invention is not limited to the steps or sequence shown above. Many variations and modifications may occur to those skilled in the art in light of the teachings of the illustrated embodiments.
Although the present invention has been described in conjunction with the preferred embodiments thereof, it will be understood by those skilled in the art that various changes, substitutions and alterations can be made herein without departing from the spirit and scope of the invention. Accordingly, the present invention should not be limited by the above-described embodiments, but should be defined by the appended claims and their equivalents.
Claims (20)
1. An etching method, comprising:
forming a modification layer with one or several atomic layer thicknesses on a selected area of the surface of a semiconductor material layer by using a modifying agent, wherein the semiconductor material layer comprises a first semiconductor material and a second semiconductor material, the selected area comprises a surface exposed to the first semiconductor material and a surface exposed to the second semiconductor material, and the rate of forming the modification layer on the surface of the second semiconductor material is greater than the rate of forming the modification layer on the surface of the first semiconductor material; and
removing the modified layer, wherein the modified layer on the surface of the first semiconductor material and the modified layer on the surface of the second semiconductor material are etched simultaneously until the modified layer on the surface of the second semiconductor material is completely removed,
wherein a thickness of the modified layer formed on the surface of the second semiconductor material is greater than a thickness of the modified layer formed on the surface of the first semiconductor material, the first semiconductor material includes Si, and the second semiconductor material includes SiGe.
2. The method of claim 1, further comprising, after removing the modifying layer: and cleaning at least the surface from which the modified layer is removed by using a second cleaning agent.
3. The method of claim 1, further comprising: and repeatedly performing the steps of forming the modified layer by using the modifier and removing the modified layer until the semiconductor material layer with the preset thickness is etched at the selected area.
4. The method of claim 1, further comprising, after forming a modified layer with a modifying agent and before removing the modified layer: and cleaning at least the surface on which the modified layer is formed with a first cleaning agent.
5. The method of claim 1, wherein the process of forming the modified layer and the process of removing the modified layer are both isotropic.
6. The method of claim 1, wherein the modifying agent reacts with selected regions of the surface of the layer of semiconductor material, and the rate of increase of the thickness of the modified layer formed decreases with increasing time of reaction with the modifying agent, at least for a period of time.
7. The method of claim 6, wherein the reaction is self-limiting.
8. The method of claim 7, wherein the modifying agent reacts with selected regions of the surface of the layer of semiconductor material until the thickness of the modifying layer of the one or several atomic layer thicknesses reaches a saturation thickness.
9. The method of any of claims 6 to 8, wherein the modification layer formed by the reaction of the one or several atomic layers at the selected region of the surface of the layer of semiconductor material with the modifying agent prevents the selected region of the surface of the layer of semiconductor material from continuing to react with the modifying agent.
10. The method of claim 1, wherein the etching can be performed with an etching precision of 0.5nm or less.
11. The method of claim 1, wherein a rate of removing the modified layer formed on the SiGe surface is greater than a rate of removing the modified layer formed on the Si surface.
12. The method of claim 1, wherein the modification layer comprises an oxide of Si and an oxide of SiGe.
13. The method of claim 1, wherein the modifying agent comprises a liquid or aqueous solution comprising one or a combination of ozone, potassium permanganate, potassium dichromate, nitric acid, sulfuric acid, and hydrogen peroxide, an oxygen-containing gas, or an oxygen-containing plasma.
14. The method of claim 13, wherein the etchant used in removing the modification layer comprises hydrofluoric acid, buffered hydrofluoric acid, BOE, hydrofluoric acid vapor, halogen hydride, or vapor thereof.
15. The method of claim 2, wherein the second cleaning agent comprises a liquid of water, highly pure deionized water, ethanol, acetone, isopropanol, or a combination thereof, or a gas of argon, helium, nitrogen, hydrogen, water vapor, or a combination thereof, or,
the second cleaning agent comprises a mixture of a liquid of water, high-purity deionized water, ethanol, acetone, isopropanol or a combination of several of the above and a surfactant and/or a hydrophobic coating additive.
16. The method of claim 4, wherein the first cleaning agent comprises a mixture of a liquid comprising water, high purity deionized water, ethanol, acetone, isopropyl alcohol, or a combination thereof, with a surfactant and/or a hydrophobic coating additive, or
The first cleaning agent comprises liquid of water, high-purity deionized water, ethanol, acetone, isopropanol or a combination of a plurality of the above, or gas of argon, helium, nitrogen, hydrogen, water vapor or a combination of a plurality of the above.
17. A method according to claim 15 or 16, wherein the surfactant comprises an organic alcohol, aldehyde, ester, amine or a hydrophilic group at one end and a hydrophobic group at the other end.
18. A method according to claim 15 or 16, wherein the hydrophobic coating additive comprises trimethylchlorosilane, (CH 3) 3 SiN(CH3) 2 Propyldimethylchlorosilane, alkyltrialkoxysilane, hexadecyltrimethoxysilane, tetraethoxysilane, 3-glycidyloxypropyltrimethoxysilane and organosilicon coupling agent R a Si(R b ) n X 3-n Wherein R is a Is C 1~24 Or a linear or branched alkyl group or an aromatic group having 1 to 8 carbon atoms from the silicon atom, R b Is C 1~6 X is a hydrolysable group, n =0, 1, 2.
19. The method of claim 18, wherein the hydrolyzable group comprises a halogen or an alkoxy group.
20. The method of claim 17, wherein the one terminal hydrophilic group comprises an-OH, -COOH group, and the one terminal hydrophobic group comprises a hydrocarbyl group.
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN1203441A (en) * | 1997-06-25 | 1998-12-30 | 西门子公司 | Method of reducing formation of watermarks on semiconductor wafers |
| CN106548944A (en) * | 2015-09-18 | 2017-03-29 | 台湾积体电路制造股份有限公司 | The manufacture method of semiconductor device |
| CN107424923A (en) * | 2017-07-06 | 2017-12-01 | 鲁汶仪器有限公司（比利时） | A kind of method from limitation accurate etching silicon |
| CN107845684A (en) * | 2017-09-30 | 2018-03-27 | 中国科学院微电子研究所 | Ring gate nano line transistor of vertical stacking and preparation method thereof |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1203441A (en) * | 1997-06-25 | 1998-12-30 | 西门子公司 | Method of reducing formation of watermarks on semiconductor wafers |
| CN106548944A (en) * | 2015-09-18 | 2017-03-29 | 台湾积体电路制造股份有限公司 | The manufacture method of semiconductor device |
| CN107424923A (en) * | 2017-07-06 | 2017-12-01 | 鲁汶仪器有限公司（比利时） | A kind of method from limitation accurate etching silicon |
| CN107845684A (en) * | 2017-09-30 | 2018-03-27 | 中国科学院微电子研究所 | Ring gate nano line transistor of vertical stacking and preparation method thereof |
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