CN118064985A - Thinning solution of wafer-level ultrathin monocrystalline germanium film and wet preparation process - Google Patents
Thinning solution of wafer-level ultrathin monocrystalline germanium film and wet preparation process Download PDFInfo
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- CN118064985A CN118064985A CN202410229276.0A CN202410229276A CN118064985A CN 118064985 A CN118064985 A CN 118064985A CN 202410229276 A CN202410229276 A CN 202410229276A CN 118064985 A CN118064985 A CN 118064985A
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- GNPVGFCGXDBREM-UHFFFAOYSA-N germanium atom Chemical compound [Ge] GNPVGFCGXDBREM-UHFFFAOYSA-N 0.000 title claims abstract description 149
- 229910052732 germanium Inorganic materials 0.000 title claims abstract description 96
- 238000002360 preparation method Methods 0.000 title claims abstract description 8
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims abstract description 61
- MHAJPDPJQMAIIY-UHFFFAOYSA-N Hydrogen peroxide Chemical compound OO MHAJPDPJQMAIIY-UHFFFAOYSA-N 0.000 claims abstract description 32
- 238000004140 cleaning Methods 0.000 claims abstract description 32
- 238000000034 method Methods 0.000 claims abstract description 32
- KRHYYFGTRYWZRS-UHFFFAOYSA-N Fluorane Chemical compound F KRHYYFGTRYWZRS-UHFFFAOYSA-N 0.000 claims abstract description 28
- LDDQLRUQCUTJBB-UHFFFAOYSA-N ammonium fluoride Chemical compound [NH4+].[F-] LDDQLRUQCUTJBB-UHFFFAOYSA-N 0.000 claims abstract description 9
- 238000001035 drying Methods 0.000 claims abstract description 8
- 239000002904 solvent Substances 0.000 claims abstract description 4
- 239000013078 crystal Substances 0.000 claims description 36
- 239000007788 liquid Substances 0.000 claims description 34
- 230000007797 corrosion Effects 0.000 claims description 32
- 238000005260 corrosion Methods 0.000 claims description 32
- 239000008367 deionised water Substances 0.000 claims description 22
- 229910021641 deionized water Inorganic materials 0.000 claims description 22
- KFZMGEQAYNKOFK-UHFFFAOYSA-N Isopropanol Chemical compound CC(C)O KFZMGEQAYNKOFK-UHFFFAOYSA-N 0.000 claims description 17
- CSCPPACGZOOCGX-UHFFFAOYSA-N Acetone Chemical compound CC(C)=O CSCPPACGZOOCGX-UHFFFAOYSA-N 0.000 claims description 16
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 claims description 16
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 claims description 16
- 238000003756 stirring Methods 0.000 claims description 11
- 238000004519 manufacturing process Methods 0.000 claims description 9
- 229910052757 nitrogen Inorganic materials 0.000 claims description 8
- VEXZGXHMUGYJMC-UHFFFAOYSA-N Hydrochloric acid Chemical compound Cl VEXZGXHMUGYJMC-UHFFFAOYSA-N 0.000 claims description 6
- NLXLAEXVIDQMFP-UHFFFAOYSA-N Ammonia chloride Chemical compound [NH4+].[Cl-] NLXLAEXVIDQMFP-UHFFFAOYSA-N 0.000 claims description 3
- 238000005406 washing Methods 0.000 claims 1
- 238000000227 grinding Methods 0.000 abstract description 2
- 238000005530 etching Methods 0.000 description 8
- 230000002378 acidificating effect Effects 0.000 description 6
- 229910000831 Steel Inorganic materials 0.000 description 4
- 230000007547 defect Effects 0.000 description 4
- 238000005516 engineering process Methods 0.000 description 4
- 239000010959 steel Substances 0.000 description 4
- 239000000758 substrate Substances 0.000 description 4
- 230000000052 comparative effect Effects 0.000 description 3
- 238000012545 processing Methods 0.000 description 3
- 230000009286 beneficial effect Effects 0.000 description 2
- 238000001312 dry etching Methods 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 239000012212 insulator Substances 0.000 description 2
- 239000000463 material Substances 0.000 description 2
- 238000012986 modification Methods 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
- 238000007254 oxidation reaction Methods 0.000 description 2
- 230000001590 oxidative effect Effects 0.000 description 2
- 239000004065 semiconductor Substances 0.000 description 2
- 230000003746 surface roughness Effects 0.000 description 2
- 238000012360 testing method Methods 0.000 description 2
- DDFHBQSCUXNBSA-UHFFFAOYSA-N 5-(5-carboxythiophen-2-yl)thiophene-2-carboxylic acid Chemical compound S1C(C(=O)O)=CC=C1C1=CC=C(C(O)=O)S1 DDFHBQSCUXNBSA-UHFFFAOYSA-N 0.000 description 1
- 239000004809 Teflon Substances 0.000 description 1
- 229920006362 Teflon® Polymers 0.000 description 1
- 239000004480 active ingredient Substances 0.000 description 1
- 230000006978 adaptation Effects 0.000 description 1
- 230000002411 adverse Effects 0.000 description 1
- 235000019270 ammonium chloride Nutrition 0.000 description 1
- 238000010923 batch production Methods 0.000 description 1
- 239000006172 buffering agent Substances 0.000 description 1
- 239000003518 caustics Substances 0.000 description 1
- 238000005520 cutting process Methods 0.000 description 1
- 238000000354 decomposition reaction Methods 0.000 description 1
- 230000003247 decreasing effect Effects 0.000 description 1
- 238000004090 dissolution Methods 0.000 description 1
- 239000000428 dust Substances 0.000 description 1
- YBMRDBCBODYGJE-UHFFFAOYSA-N germanium oxide Inorganic materials O=[Ge]=O YBMRDBCBODYGJE-UHFFFAOYSA-N 0.000 description 1
- 230000017525 heat dissipation Effects 0.000 description 1
- 239000010410 layer Substances 0.000 description 1
- 238000005259 measurement Methods 0.000 description 1
- 238000004377 microelectronic Methods 0.000 description 1
- 230000003287 optical effect Effects 0.000 description 1
- 239000007800 oxidant agent Substances 0.000 description 1
- PVADDRMAFCOOPC-UHFFFAOYSA-N oxogermanium Chemical compound [Ge]=O PVADDRMAFCOOPC-UHFFFAOYSA-N 0.000 description 1
- 239000002245 particle Substances 0.000 description 1
- 239000002957 persistent organic pollutant Substances 0.000 description 1
- 239000002344 surface layer Substances 0.000 description 1
- 238000003631 wet chemical etching Methods 0.000 description 1
Classifications
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- C—CHEMISTRY; METALLURGY
- C30—CRYSTAL GROWTH
- C30B—SINGLE-CRYSTAL GROWTH; UNIDIRECTIONAL SOLIDIFICATION OF EUTECTIC MATERIAL OR UNIDIRECTIONAL DEMIXING OF EUTECTOID MATERIAL; REFINING BY ZONE-MELTING OF MATERIAL; PRODUCTION OF A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; SINGLE CRYSTALS OR HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; AFTER-TREATMENT OF SINGLE CRYSTALS OR A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; APPARATUS THEREFOR
- C30B33/00—After-treatment of single crystals or homogeneous polycrystalline material with defined structure
- C30B33/08—Etching
- C30B33/10—Etching in solutions or melts
-
- C—CHEMISTRY; METALLURGY
- C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
- C23F—NON-MECHANICAL REMOVAL OF METALLIC MATERIAL FROM SURFACE; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL; MULTI-STEP PROCESSES FOR SURFACE TREATMENT OF METALLIC MATERIAL INVOLVING AT LEAST ONE PROCESS PROVIDED FOR IN CLASS C23 AND AT LEAST ONE PROCESS COVERED BY SUBCLASS C21D OR C22F OR CLASS C25
- C23F1/00—Etching metallic material by chemical means
- C23F1/02—Local etching
-
- C—CHEMISTRY; METALLURGY
- C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
- C23F—NON-MECHANICAL REMOVAL OF METALLIC MATERIAL FROM SURFACE; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL; MULTI-STEP PROCESSES FOR SURFACE TREATMENT OF METALLIC MATERIAL INVOLVING AT LEAST ONE PROCESS PROVIDED FOR IN CLASS C23 AND AT LEAST ONE PROCESS COVERED BY SUBCLASS C21D OR C22F OR CLASS C25
- C23F1/00—Etching metallic material by chemical means
- C23F1/10—Etching compositions
- C23F1/14—Aqueous compositions
- C23F1/16—Acidic compositions
- C23F1/30—Acidic compositions for etching other metallic material
-
- C—CHEMISTRY; METALLURGY
- C30—CRYSTAL GROWTH
- C30B—SINGLE-CRYSTAL GROWTH; UNIDIRECTIONAL SOLIDIFICATION OF EUTECTIC MATERIAL OR UNIDIRECTIONAL DEMIXING OF EUTECTOID MATERIAL; REFINING BY ZONE-MELTING OF MATERIAL; PRODUCTION OF A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; SINGLE CRYSTALS OR HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; AFTER-TREATMENT OF SINGLE CRYSTALS OR A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; APPARATUS THEREFOR
- C30B29/00—Single crystals or homogeneous polycrystalline material with defined structure characterised by the material or by their shape
- C30B29/02—Elements
- C30B29/08—Germanium
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P70/00—Climate change mitigation technologies in the production process for final industrial or consumer products
- Y02P70/50—Manufacturing or production processes characterised by the final manufactured product
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- Chemical & Material Sciences (AREA)
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- Materials Engineering (AREA)
- Metallurgy (AREA)
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- Crystallography & Structural Chemistry (AREA)
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Abstract
The invention discloses a thinning solution and a wet preparation process of a wafer-level ultrathin monocrystalline germanium film, wherein the thinning solution comprises the following components: 1-5% of ammonia fluoride; 2-8% of hydrogen peroxide; 0.5-3% of hydrofluoric acid; the solvent is water, and the percentage is mass percent; after the germanium wafer is cleaned, placing the germanium wafer into the thinning solution for thinning; after the thinning is finished, cleaning and drying are carried out. The germanium film obtained by the process can realize effective control of thickness, and different thicknesses can be selected according to different requirements. The germanium film obtained by the process does not need to be mechanically ground, and the problems of damage layer caused by grinding, warping caused by stress and the like do not need to be considered. The germanium film obtained by the process has extremely high crystallinity and sub-nanometer roughness, and basically meets the requirements of various devices.
Description
Technical Field
The invention belongs to the technical field of semiconductor material processing, and particularly relates to a thinning solution of a wafer-level ultrathin monocrystalline germanium film and a wet preparation process.
Background
The statements herein merely provide background information related to the present disclosure and may not necessarily constitute prior art.
The monocrystalline germanium film is an important semiconductor material and is widely applied to the fields of infrared optical devices, microelectronic chip technology, flexible solar cells and the like. The preparation of the wafer-level ultrathin monocrystalline germanium film which can meet the requirements of cleaning and subsequent processing and realize batch production is very important. The existing method for preparing the monocrystalline germanium film comprises the technologies of epitaxial growth of the monocrystalline germanium film on a substrate, selective corrosion of germanium on an insulator to release the germanium film, dry etching thinning of ICP-RIE and the like. The substrate epitaxial growth technology requires lattice adaptation of the substrate and the germanium single crystal, has high cost, and cannot release the germanium film later. The technology of selective corrosion release of germanium on insulator (GeOI) has complex process, high cost and uncontrollable thickness of germanium film. The ICP-RIE dry etching thinning technique is to dry etch and thin a thick germanium wafer into a germanium film, but the germanium film has the problems of high roughness, surface damage, need of additional substrate support and the like.
Disclosure of Invention
In order to solve the problems of complex process, high cost, excessively low thickness, uncontrollable thickness, high roughness, surface damage and the like of the germanium film in the prior art, the invention provides a thinning solution of a wafer-level ultrathin monocrystalline germanium film and a wet preparation process.
In order to achieve the above object, the present invention is realized by the following technical scheme:
in a first aspect, the present invention provides a thinning solution for a wafer-level ultrathin single crystal germanium film, comprising: 1-5% of ammonia fluoride; 2-8% of hydrogen peroxide; 0.5-3% of hydrofluoric acid; the solvent is water and the percentage is mass percent.
The wet chemical etching principle of single crystal germanium is that oxidizing single crystal germanium with oxidant, and then dissolving oxide with corrosive agent, and the process is repeated to realize the uniform removal of the surface layer of single crystal germanium wafer.
The ammonia fluoride plays a role of buffering agent, corrosion is divided into two steps of oxidization and dissolution, the hydrogen peroxide plays a role of oxidization, the hydrofluoric acid plays a role of dissolving germanium oxide, and the corrosion thinning rate of the solution to the germanium sheet can be controlled by controlling one step. The concentration of the active ingredients of the solution is reduced with the increase of the corrosion time without adding ammonia fluoride, so that the thinning rate is also reduced with the increase of the time. And ammonia fluoride is added into the solution, and the consumed hydrofluoric acid can be ionized and supplemented by the ammonia fluoride, so that the relative stability of the concentration of the hydrofluoric acid is ensured, and the stability of the corrosion thinning rate of the germanium sheet is further ensured. A stable etch thinning rate is important to control the thickness of the final germanium film.
In some embodiments, the mass ratio of the ammonia fluoride, the hydrogen peroxide and the hydrofluoric acid in the thinning solution is 2-3:4-5:1-3; preferably 3:4 to 5:2.
In a second aspect, the invention provides a wet process for preparing a wafer-level ultrathin monocrystalline germanium film, comprising the following steps:
after the germanium wafer is cleaned, placing the germanium wafer into the thinning solution for thinning;
After the thinning is finished, cleaning and drying are carried out.
In some embodiments, the annular edge of the germanium wafer is protected from the thinning solution prior to thinning. The annular edge of the germanium wafer is protected, so that the middle area of the germanium wafer is exposed, only the middle area is thinned, and the formed rigid annular structure can play a supporting role on the germanium film, so that the germanium film is convenient to move and process.
Preferably, the protection treatment is to use an annular clamp to carry out annular clamping on the edge of the germanium wafer.
Further preferably, before immersing in the thinning liquid, the germanium wafer is cleaned, and then the germanium wafer is cleaned according to the sequence of acetone, isopropanol, ethanol and deionized water; and after clamping and fixing the germanium wafer by adopting the annular clamp, cleaning by deionized water again.
Acetone, isopropyl alcohol and ethanol are used for cleaning organic pollutants on germanium sheets, and deionized water can clean residual organic cleaning liquid.
In order to avoid pollution (the pollution is mainly dust particles) in the clamp and clamping process, after the annular clamp is used for clamping and fixing the germanium wafer, deionized water is needed to be used for cleaning again, and if the germanium wafer is not cleaned cleanly, point-shaped bulges can be corroded on the surface of the germanium wafer.
Preferably, the protection treatment is to provide a corrosion-resistant mask at the edge of the germanium wafer.
In some embodiments, the temperature of the thinning solution is 20-40 ℃, preferably 20-30 ℃, during the thinning process.
The thinning temperature affects the corrosion thinning rate and the surface quality of the finished germanium film. The temperature is too high, on one hand, hydrogen peroxide can be promoted to decompose, and generated bubbles can lead to corrosion of punctiform bulges on the surface of the germanium film, so that the surface quality of the finished germanium film is poor. On the other hand, the corrosion thinning speed can be improved, and when the thinning speed is higher, the thinning uniformity can be influenced, so that the quality of the finished germanium film is not improved.
In addition, the inventor also found that when the temperature of the thinning solution is too high, such as more than room temperature, the temperature of the thinning solution is unevenly distributed due to different heat dissipation rates of different areas of the thinning solution, which has adverse effects on improving the quality of the germanium film. And the thinner the solution temperature is, the more the temperature is close to the room temperature, the extra influence caused by the non-uniformity of the solution temperature is reduced.
Preferably, the thinning liquid is stirred in the thinning process, and the stirring speed is 100-300rpm.
On the one hand, stirring can ensure that the components and the temperature of the solution are as uniform as possible in the corrosion thinning process, and the uniformity of corrosion thinning is ensured.
On the other hand, bubbles generated by the decomposition of hydrogen peroxide can be adsorbed on the germanium sheet, so that punctiform bulges are corroded on the surface, and the size of the bulges is 5-10 microns. If stirring is not carried out, tiny bubbles adsorbed on the surface of the germanium sheet can not be separated in time, so that large-area water trace defects are formed on the surface of the finished germanium film, and the water trace defects are formed by dense punctiform protrusions. The number of bubbles adsorbed on the germanium sheet can be reduced by stirring, which is helpful for improving the quality of the germanium film.
In some embodiments, after the thinning is completed, rinsing is first performed and then rinsed with running water. So as to ensure that no thinning liquid residue exists on the surface of the germanium film.
Preferably, after the cleaning is completed, the germanium film is purged by a small flow nitrogen gun to remove residual water.
In some embodiments, if the thickness of the germanium film after one thinning is not satisfactory, repeated thinning is performed.
The beneficial effects achieved by one or more embodiments of the present invention described above are as follows:
According to the wafer-level ultrathin single-crystal germanium film wet preparation process, the edge of the wafer is protected from being corroded by the thinning liquid by the annular clamp, and the formed rigid annular structure plays a role in supporting the germanium film, is beneficial to subsequent movement and processing and has extremely strong flexibility. The germanium film obtained by the process can realize effective control of thickness, and different thicknesses can be selected according to different requirements. The germanium film obtained by the process does not need to be mechanically ground, and the problems of damage layer caused by grinding, warping caused by stress and the like do not need to be considered. The germanium film obtained by the process has extremely high crystallinity and sub-nanometer roughness, and basically meets the requirements of various devices. The process is easy to operate, reliable and stable, low in cost, uniform in surface quality of the obtained germanium film and suitable for mass production.
Drawings
The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and together with the description serve to explain the invention.
FIG. 1 is a schematic view of a matched thinning apparatus of the present invention.
FIG. 2 is a schematic view of a ring clamp in a matched thinning apparatus of the present invention.
FIG. 3 is a schematic view of a wafer level ultra-thin single crystal germanium film made in accordance with the present invention
Wherein, 1-a water tank; 2-an annular clamp; 3-a magnetic stirrer; 4-magnons; 5-fixing the screw; 6-wafer.
Detailed Description
It should be noted that the following detailed description is illustrative and is intended to provide further explanation of the invention. Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs.
The invention is further illustrated below with reference to examples.
Example 1
The crystal orientation of the double-throwing germanium wafer is N <100>, the resistivity is 1-10ohm cm, and the thickness is 160 mu m. The surface of the germanium sheet is smooth and has no damage before corrosion.
Firstly fixing the edge of a wafer, then immersing the wafer into thinning liquid for thinning, and finally cleaning and drying, wherein the method specifically comprises the following steps of:
1. cleaning the germanium wafer, namely cleaning the germanium wafer in the sequence of acetone, isopropanol, ethanol and deionized water, fixing the germanium wafer by using two annular clamps, and cleaning the germanium wafer again by using deionized water; then immersing the steel plate into an acidic thinning liquid with the temperature of 40 ℃ for corrosion thinning, and continuously stirring the thinning liquid in the corrosion thinning process; the thinning liquid comprises the following components in percentage by mass: hydrogen peroxide: hydrofluoric acid: deionized water = 6:9:4:130; the etching time is 37min, and the thickness of the germanium single crystal wafer can be removed in the step of 150-153 mu m; and then the clamp with the germanium single crystal is taken out.
2. The ring-shaped clamp with the germanium film sheet is put into an overflow water box filled with water for rinsing for 30 seconds, then the overflow water box is removed, and the water gun is used for rinsing for 30 seconds. The ring clamp was removed, rinsed with a water gun for 60 seconds, and finally blow-dried with nitrogen for 240 seconds (20 ℃ C.).
Example 2
The crystal orientation of the double-throwing germanium wafer is N <100>, the resistivity is 1-10ohm cm, and the thickness is 161 mu m. The surface of the germanium sheet is smooth and has no damage before corrosion.
Firstly fixing the edge of a wafer, then immersing the wafer into thinning liquid for thinning, and finally cleaning and drying, wherein the method specifically comprises the following steps of:
1. Cleaning the germanium wafer, namely cleaning the germanium wafer in the sequence of acetone, isopropanol, ethanol and deionized water, fixing the germanium wafer by using two annular clamps, and cleaning the germanium wafer again by using deionized water; then immersing the steel plate into an acidic thinning liquid 2 with the temperature of 40 ℃ for corrosion, and continuously stirring the thinning liquid in the corrosion thinning process; the thinning liquid 2 comprises the following components in percentage by mass: hydrogen peroxide: hydrofluoric acid: deionized water = 6:9:4:230; the etching time is 65 minutes, and the thickness of the germanium single crystal wafer can be removed by the step of 150-153 mu m; and then the clamp with the germanium single crystal is taken out.
2. Then the annular clamp with the germanium film sheet is put into an overflow water box filled with water for rinsing for 30 seconds, and is rinsed for 30 seconds by a water gun, and then the overflow water box is removed. The ring clamp was removed, rinsed with a water gun for 60 seconds, and finally blow-dried with nitrogen for 240 seconds (20 ℃ C.).
Example 3
The crystal orientation of the double-throwing germanium wafer is N <100>, the resistivity is 1-10ohm cm, and the thickness is 158 mu m. The surface of the germanium sheet is smooth and has no damage before corrosion.
Firstly fixing the edge of a wafer, then immersing the wafer into thinning liquid for thinning, and finally cleaning and drying, wherein the method specifically comprises the following steps of:
1. Cleaning the germanium wafer, namely cleaning the germanium wafer in the sequence of acetone, isopropanol, ethanol and deionized water, fixing the germanium wafer by using two annular clamps, and cleaning the germanium wafer again by using deionized water; then immersing the steel plate into an acidic thinning liquid with the temperature of 20 ℃ for corrosion, continuously stirring the thinning liquid in the corrosion thinning process, wherein the thinning liquid comprises the following components in percentage by mass: hydrogen peroxide: hydrofluoric acid: deionized water = 6:9:4:230; etching time is 103 minutes, and the thickness of the germanium single crystal wafer can be removed at 153-155 mu m; and then the clamp with the germanium single crystal is taken out.
2. Then the annular clamp with the germanium film sheet is put into an overflow water box filled with water for rinsing for 30 seconds, and is rinsed for 30 seconds by a water gun, and then the overflow water box is removed. The ring clamp was removed, rinsed with a water gun for 60 seconds, and finally blow-dried with nitrogen for 240 seconds (20 ℃ C.).
Example 4
The crystal orientation of the double-throwing germanium wafer is N <100>, the resistivity is 1-10ohm cm, and the thickness is 156 mu m. The surface of the germanium sheet is smooth and has no damage before corrosion.
Firstly fixing the edge of a wafer, then immersing the wafer into thinning liquid for thinning, and finally cleaning and drying, wherein the method specifically comprises the following steps of:
1. Cleaning the germanium wafer, namely cleaning the germanium wafer in the sequence of acetone, isopropanol, ethanol and deionized water, fixing the germanium wafer by using two annular clamps, and cleaning the germanium wafer again by using deionized water; then immersing the steel plate into an acidic thinning liquid with the temperature of 15 ℃ for corrosion, continuously stirring the thinning liquid in the corrosion thinning process, wherein the thinning liquid comprises the following components in percentage by mass: hydrogen peroxide: hydrofluoric acid: deionized water = 6:9:4:230; etching for 131 min to eliminate germanium monocrystal with thickness of 150-152 microns; and then the clamp with the germanium single crystal is taken out.
2. Then the annular clamp with the germanium film sheet is put into an overflow water box filled with water for rinsing for 30 seconds, and is rinsed for 30 seconds by a water gun, and then the overflow water box is removed. The ring clamp was removed, rinsed with a water gun for 60 seconds, and finally blow-dried with nitrogen for 240 seconds (20 ℃ C.).
Comparative example 1
The difference from example 1 is that: the ammonium fluoride was omitted, and the other components were the same as in example 1, but the corrosion rate was unstable and decreased slowly with the increase of the corrosion time.
Comparative example 2
The difference from example 1 is that: the hydrogen peroxide is omitted, and the rest is the same as that of the embodiment 1, so that the germanium sheet is not corroded and thinned.
Comparative example 3
The difference from example 1 is that: the step of stirring the thinning liquid continuously during the etching thinning process was omitted, and the rest was the same as in example 1. The effect on the finished germanium film is large, and the large-area water trace defect appears on the surface of the germanium film. The water trace defect is formed by dense dot-shaped bulges, and the size of each bulge is about 5-10 microns.
After the etching step is completed, the thickness of the germanium film is tested by a spiral micrometer, and the surface roughness is tested by an atomic force microscope. The test results are shown in Table 1.
TABLE 1
Conclusion: as can be seen from the data in table 1, the proportion and temperature of the thinning liquid affect the thinning speed, and the final thickness of the germanium film can be effectively controlled by controlling the thinning time. The reducing liquid with different proportions has small influence on the surface quality of the germanium film, and the roughness is below 1 nm.
Example 5
The crystal orientation of the double-throwing germanium wafer is N <100>, the resistivity is 1-10ohm cm, and the thickness is 171 mu m. The surface of the germanium sheet is smooth and has no damage before corrosion.
The method specifically comprises the following steps:
Cutting a germanium wafer into 10 multiplied by 10mm sample pieces, cleaning the wafer according to the sequence of acetone, isopropanol, ethanol and deionized water, fixing the germanium wafer by using two Teflon ring clamps, and cleaning the wafer again by using deionized water; the thinning liquid comprises the following components in percentage by mass: hydrogen peroxide: hydrofluoric acid: deionized water = 6:9:4:230. Immersing the sample into an acidic thinning liquid with the temperature of 40 ℃ for thinning, continuously stirring the thinning liquid in the corrosion thinning process, taking out and cleaning every 5 minutes of corrosion, and measuring the thickness. The germanium single crystal wafer was rinsed with a water gun for 60 seconds and then dried with nitrogen for 240 seconds (20 ℃ C.).
The thickness of the cleaned germanium single crystal was measured by a screw micrometer, and the measurement results are shown in table 2.
TABLE 2
| Thinning time/min | Thickness/. Mu.m |
| 0 | 171 |
| 5 | 151 |
| 10 | 130 |
| 15 | 109 |
| 20 | 88 |
| 25 | 68 |
| 30 | 47 |
| 35 | 27 |
Conclusion: as is clear from the data in table 2, when the single crystal germanium wafer is thinned using the thinning liquid, the thinning rate is stable and controllable. Along with the thinning work, the thinning speed is basically unchanged, and the effective components of the thinning liquid are proved to be stable, so that the effective control of the thickness of the germanium film can be realized.
Example 6
The crystal orientation of the double-throwing germanium wafer is N <100>, the resistivity is 1-10ohm cm, and the thickness is 158 mu m. The surface of the germanium sheet is smooth and has no damage before corrosion.
Firstly fixing the edge of a wafer, then immersing the wafer into thinning liquid for thinning, and finally cleaning and drying, wherein the method specifically comprises the following steps of:
1. The germanium wafer is fixed by two annular clamps and is immersed into an acidic thinning liquid 3 with the temperature of 20 ℃ for corrosion, and the thinning liquid 2 is prepared from ammonium chloride in proportion: hydrogen peroxide: hydrochloric acid: deionized water=3:3:2:50 (mass ratio); the etching time is 180 minutes, and the thickness of the germanium single crystal wafer can be removed by 60-63 mu m; and then taking out the clamping plug with the germanium single crystal.
2. Then the annular clamp with the germanium film sheet is put into an overflow water box filled with water for rinsing for 30 seconds, and is rinsed for 30 seconds by a water gun, and then the overflow water box is removed. The ring clamp was removed, rinsed with a water gun for 60 seconds, and finally blow-dried with nitrogen for 240 seconds (20 ℃ C.).
After the etching step is completed, the thickness of the germanium film is tested by a spiral micrometer tester, and the surface roughness is tested by an atomic force microscope. The test results are shown in Table 3.
TABLE 3 Table 3
Conclusion: as can be seen from the data in table 3, the thinning of the single crystal germanium wafer can be realized by using the thinning solution in which hydrochloric acid is used instead of hydrofluoric acid, and the thinning speed is stable and controllable.
The above description is only of the preferred embodiments of the present invention and is not intended to limit the present invention, but various modifications and variations can be made to the present invention by those skilled in the art. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.
Claims (10)
1. The thinning solution of the wafer-level ultrathin monocrystalline germanium film is characterized in that: the composition is as follows: 1-5% of ammonia fluoride; 2-8% of hydrogen peroxide; 0.5-3% of hydrofluoric acid; the solvent is water, and the percentage is mass percent;
Or, the composition is as follows: 2-8% of ammonia chloride; 2-8% of hydrogen peroxide; 1-5% of hydrochloric acid; the solvent is water and the percentage is mass percent.
2. The thinning solution of a wafer-level ultra-thin single crystal germanium film according to claim 1, wherein: in the thinning solution, the mass ratio of the ammonia fluoride to the hydrogen peroxide to the hydrofluoric acid is 2-3:4-5:1-3; preferably 3:4 to 5:2.
3. A wet preparation process of a wafer-level ultrathin monocrystalline germanium film is characterized by comprising the following steps of: the method comprises the following steps:
after cleaning the germanium wafer, placing the germanium wafer into the thinning solution according to claim 1 for thinning;
After the thinning is finished, cleaning and drying are carried out.
4. The wet process for preparing a wafer-level ultra-thin single crystal germanium film according to claim 3, wherein: before thinning, the annular edge of the germanium wafer is subjected to protection treatment so as to shield the annular edge from the thinning solution.
5. The wet process for preparing a wafer-level ultrathin single crystal germanium film according to claim 4, wherein the wafer-level ultrathin single crystal germanium film comprises the following steps: the protection treatment is to carry out annular clamping on the edge of the germanium wafer by adopting an annular clamp;
Preferably, before immersing in the thinning liquid, the germanium wafer is cleaned, and then the germanium wafer is cleaned according to the sequence of acetone, isopropanol, ethanol and deionized water; and after clamping and fixing the germanium wafer by adopting the annular clamp, cleaning the germanium wafer by deionized water again.
6. The wet process for preparing a wafer-level ultrathin single crystal germanium film according to claim 4, wherein the wafer-level ultrathin single crystal germanium film comprises the following steps: the protection treatment is to arrange a corrosion-resistant mask at the edge of the germanium wafer.
7. The wet process for preparing a wafer-level ultra-thin single crystal germanium film according to claim 3, wherein: in the thinning process, the temperature of the thinning solution is 20-40 ℃, preferably 20-30 ℃;
Preferably, the thinning liquid is stirred in the thinning process, and the stirring speed is 100-300rpm.
8. The wet process for preparing a wafer-level ultra-thin single crystal germanium film according to claim 3, wherein: after the thinning is finished, rinsing is carried out first, and then washing is carried out by running water.
9. The wet process for preparing a wafer-level ultra-thin single crystal germanium film according to claim 3, wherein: after the cleaning is completed, the germanium film is purged by a small-flow nitrogen gun to remove residual water.
10. The wet process for preparing a wafer-level ultra-thin single crystal germanium film according to claim 3, wherein: if the thickness of the once thinned germanium film can not meet the requirement, repeated thinning is carried out.
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