A cleaning method for high-purity single-crystal GaN

Abstract

The present invention relates to the technical field of high-purity single-crystal GaN production, and specifically to a method for cleaning high-purity single-crystal GaN; comprising the following steps: S1, preparing an APM-like solvent; S2, an organic pollution removal unit and a metal pollution removal unit; using an APM-like solvent to clean the single-crystal GaN; S3, surface state optimization: placing the single-crystal GaN treated in step S2 into a pickling solution for pickling; S4, surface rinsing and drying: using a rinse solution to rinse the single-crystal GaN after pickling in step S3, rinse the impurity components generated during the pickling process, and then dry the sample to complete the cleaning process. The present invention can be used to remove particles, metal pollution, and organic pollution at the same time through APM-like solvent cleaning, pickling, and rinsing and drying, thereby realizing the preparation of high-purity single-crystal gallium nitride; at the same time, it can also effectively modify the surface state of the single-crystal gallium nitride, reduce the dislocation of the single-crystal gallium nitride, and enhance the electronic conductivity of the single-crystal gallium nitride.

Description

Technical Field

[0001] The invention relates to the technical field of high-purity single-crystal GaN production, and in particular to a method for cleaning high-purity single-crystal GaN. Background Art

[0002] The surface contamination of semiconductors mainly includes particulate and metal contamination, organic contamination and surface state (high defect density, etc.), which may come from water, atmosphere, equipment, various chemical reagents and pollution caused by human processing. If there are trace impurities on the surface of semiconductor materials, such as sodium ions, metals and other impurity particles, they will diffuse and spread during high temperature processes and enter the interior of the semiconductor material, which is not good for the device. To obtain high-quality semiconductor devices, GaN must have a very clean surface.

[0003] Currently, semiconductor cleaning includes two cleaning methods: dry and wet. Currently, the wet method dominates the market due to its advantages of low cost and high production capacity.

[0004] Wet cleaning mainly includes RCA cleaning and ultrasonic cleaning. Among them, the RCA cleaning method uses a mixture of hydrogen peroxide and acid / alkaline solution for two-step oxidation to effectively remove organic matter, particles, metals and other pollutants on the semiconductor surface. However, the RCA cleaning method can remove pollutant films on the surface of the wafer but cannot remove particles; it needs to be carried out in a high temperature environment; it consumes a lot of chemicals, which will increase the roughness of the silicon wafer; and the large amount of emissions pollutes the environment. The ultrasonic cleaning method immerses the wafer in the cleaning liquid and uses ultra-high frequency sound wave energy to effectively remove particles on the front and back of the wafer. Its advantages are fast cleaning speed, good cleaning effect, ability to clean silicon wafer surfaces of various complex shapes, and easy to realize remote control and automation; its disadvantages are that when the particle size is small, the cleaning effect is not good, and when the cavitation bubble explodes, the huge energy will cause certain damage to the semiconductor.

[0005] Dry cleaning mainly includes gas phase cleaning and UV-ozone cleaning. The gas phase cleaning method rotates the semiconductor wafer at a low speed, and then increases the speed to dry the wafer. HF vapor can remove part of the oxide film contamination. Its advantages are that it can effectively clean those parts with deeper structures (such as grooves), and it is also better for cleaning particles on the surface of silicon wafers, and it will not produce secondary pollution; its disadvantage is that HF ​​vapor can remove natural oxides, but it cannot effectively remove metal pollution. The UV-ozone cleaning method uses short-wavelength ultraviolet light generated by a mercury lamp in an oxygen atmosphere to irradiate the semiconductor wafer. It is suitable for oxidizing and removing organic matter, but it cannot clean general inorganic contamination.

[0006] During wet cleaning, chemical solvents or deionized water are used to clean semiconductor wafers. However, wet cleaning requires rinsing and drying of the semiconductor wafers. At the same time, with the miniaturization of semiconductors, more and more semiconductors cannot be cleaned by wet cleaning, and there are also problems such as wafer damage, chemical contamination, and secondary cross-contamination. Dry cleaning uses gas to remove surface organic matter or oxide film, but it is not effective for removing particles and metal pollution. Therefore, how to simultaneously meet the high-quality cleaning of particles, metal pollution and organic pollution is an urgent problem to be solved in the existing high-purity single crystal GaN cleaning field. Summary of the invention

[0007] Technical issues solved

[0008] In view of the above-mentioned shortcomings of the prior art, the present invention provides a method for cleaning high-purity single crystal GaN, which can effectively solve the problem that the existing high-purity single crystal GaN cleaning method in the prior art cannot simultaneously meet the high-quality cleaning requirements for particles, metal pollution and organic pollution.

[0009] Technical Solution

[0010] To achieve the above objectives, the present invention is implemented through the following technical solutions:

[0011] The present invention provides a method for cleaning high-purity single-crystal GaN, comprising the following steps:

[0012] S1. Preparing an APM-like solvent: mixing an alkaline raw material, an oxidant raw material and water in a certain proportion to form an APM-like solvent, wherein the concentration of the alkaline raw material after preparation is 0.001%-10%, and the concentration of the oxidant raw material is 0.01%-30%;

[0013] Wherein, the alkaline raw material is one or more of aluminum reagent, cupric iron reagent, ammonium sulfide, ammonium hydrogen sulfide, ammonium chloride, ammonium bromide, tetramethylammonium bromide, tetrapropylammonium bromide, tetraethylammonium bromide, hexadecyltrimethylammonium bromide, hexadecyltrimethylammonium chloride, hexadecyltrimethylammonium bromide, benzyltriethylammonium bromide, ammonium fluoroborate, ammonium fluoride, ammonium formate, ammonium formate, ammonium citrate, sodium carbonate, potassium carbonate, lithium carbonate and rubidium carbonate;

[0014] The oxidant raw material is one or more of sodium borate, sodium thiosulfate, strontium peroxide, peracetic acid, peroxyethanol, sodium dichromate, chromic acid, potassium permanganate, ammonium persulfate and potassium perborate;

[0015] S2, organic pollution removal unit and metal pollution removal; using APM-like solvent to clean the single crystal GaN under ventilation conditions;

[0016] S3, surface state optimization: placing the single crystal GaN treated in step S2 into a pickling solution for pickling;

[0017] S4, surface washing and drying: the single crystal GaN after pickling in step S3 is washed with a washing liquid to wash away the impurity components generated during the pickling process, and then vacuum dried at 60-100° C. for 10-24 hours to complete the washing process.

[0018] During production, firstly, part of the alkali solution contained in the APM-like solvent is used to dissolve the organic polluting components, and at the same time, the Ga3+ ions on the surface of the single-crystalline GaN are precipitated; at the same time, the particles and metal impurity pollution on the surface of the single-crystalline GaN are removed, and the polycrystalline impurities are removed, thereby avoiding the surface roughness of the single-crystalline GaN caused by etching with strong alkali solution; then, the residual metal ions and part of the alkali solution are removed by pickling, and at the same time, the O and C elements on the surface of the single-crystalline GaN are removed, the surface flatness of the single-crystalline GaN is adjusted, the electron transfer rate is enhanced, the surface dislocations of the single-crystalline GaN are reduced, and the electronic conductivity of the single-crystalline gallium nitride is enhanced; finally, the surface of the single-crystalline GaN is rinsed to rinse the impurity components generated by the pickling process, and then the sample is dried to complete the cleaning process.

[0019] Therefore, the cleaning method provided by the present invention can be used to remove particles, metal pollution and organic pollution at the same time, thereby realizing the preparation of high-purity single-crystalline gallium nitride; at the same time, it can also effectively modify the surface state of single-crystalline gallium nitride, reduce the dislocation of single-crystalline gallium nitride, and enhance the electronic conductivity of single-crystalline gallium nitride.

[0020] Furthermore, the alkaline raw material is a mixture of ammonium sulfide, ammonium hydrogen sulfide, ammonium fluoride and ammonium citrate, and the weight ratio thereof is (0.1-0.9):(0.2-0.8):(0.05-0.3):(0.01-0.1).

[0021] Furthermore, the oxidant raw material is a mixture of peracetic acid, peracetic acid and sodium borate, and the weight ratio thereof is (0.2-0.7):(0.05-0.3):(0.05-0.2).

[0022] Furthermore, the pickling time of step S3 is 10-30 minutes.

[0023] Furthermore, the pickling solution is one or more of perchloric acid solution, selenic acid solution, hydrofluoric acid solution, hydroiodic acid, hydrobromic acid, chloric acid, bromic acid, metaperiodic acid, permanganic acid, 2-chloroethanethiol, 2,4,6-trinitrophenol, trifluoroacetic acid, trichloroacetic acid, methanesulfonic acid and benzenesulfonic acid, and the concentration of the pickling solution is 0.1-45%.

[0024] Furthermore, the pickling solution is a mixture of hydrofluoric acid, 2-chloroethanethiol, trifluoroacetic acid and trichloroacetic acid, and the weight ratio thereof is (0.1-0.5):(0.01-0.3):(0.05-0.1):(0.005-0.1).

[0025] Furthermore, the flushing time of step S4 is 1-10 minutes.

[0026] Furthermore, the flushing liquid is one or more of ultrapure water, acetone, isopropanol and ethanol.

[0027] Furthermore, after the cleaning in step S2 is completed, there is a rinsing procedure: using an APM-like solvent to rinse off the impurity components generated on the surface of the single crystal GaN during the cleaning process in step S2, and the rinsing time is 5-10 minutes.

[0028] Beneficial Effects

[0029] Compared with the known public technology, the technical solution provided by the present invention has the following beneficial effects:

[0030] The present invention can be used to remove particles, metal pollution and organic pollution at the same time through APM-like solvent cleaning, acid washing and rinsing and drying, thereby realizing the preparation of high-purity single-crystalline gallium nitride; at the same time, it can also effectively modify the surface state of single-crystalline gallium nitride, reduce the dislocation of single-crystalline gallium nitride, and enhance the electronic conductivity of single-crystalline gallium nitride. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the prior art descriptions are briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention, and for ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0032] Figure 1 This is a flow chart of the method for cleaning the surface of single crystal GaN of the present invention.

[0033] The symbols in the figure represent:.

[0034] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0035] The present invention will be further described below in conjunction with the embodiments.

[0036] Embodiment 1:

[0037] like Figure 1 As shown, a method for cleaning high-purity single-crystal GaN comprises the following steps:

[0038] S1. Preparing an APM-like solvent: mixing an alkaline raw material, an oxidant raw material and water in a certain proportion to form an APM-like solvent, wherein the concentration of the alkaline raw material after preparation is 10%, and the concentration of the oxidant raw material is 30%;

[0039] Wherein, the alkaline raw material is a mixture of ammonium sulfide, ammonium hydrogen sulfide, ammonium fluoride and ammonium citrate, and the weight ratio thereof is 0.4:0.6:0.1:0.05;

[0040] The oxidant raw material is a mixture of peroxyethanol, peracetic acid and sodium borate, and the weight ratio thereof is 0.3:0.25:0.1;

[0041] S2, organic pollution removal unit and metal pollution removal: use APM-like solvent to clean the single crystal GaN, and then use APM-like solvent to rinse off the impurity components generated on the surface of the single crystal GaN during the cleaning process. The rinsing time is 10 minutes;

[0042] S3, surface state optimization: the single crystal GaN treated in step S2 is placed in an acid wash solution for acid washing for 30 minutes; the acid wash solution is a mixture of hydrofluoric acid, 2-chloroethanethiol, trifluoroacetic acid and trichloroacetic acid, and the weight ratio thereof is 0.4:0.2:0.05:0.1;

[0043] S4, surface rinsing and drying: The single crystal GaN after pickling in step S3 is rinsed with ultrapure water for 5 minutes to rinse the impurity components generated during the pickling process, and then it is vacuum dried at 75° C. for 12 hours to complete the cleaning process.

[0044] During production, firstly, part of the alkali solution contained in the APM-like solvent is used to dissolve the organic polluting components, and at the same time, the Ga3+ ions on the surface of the single-crystalline GaN are precipitated; at the same time, the particles and metal impurity pollution on the surface of the single-crystalline GaN are removed, and the polycrystalline impurities are removed, thereby avoiding the surface roughness of the single-crystalline GaN caused by etching with strong alkali solution; then, the residual metal ions and part of the alkali solution are removed by pickling, and at the same time, the O and C elements on the surface of the single-crystalline GaN are removed, the surface flatness of the single-crystalline GaN is adjusted, the electron transfer rate is enhanced, the surface dislocations of the single-crystalline GaN are reduced, and the electronic conductivity of the single-crystalline gallium nitride is enhanced; finally, the surface of the single-crystalline GaN is rinsed to rinse the impurity components generated by the pickling process, and then the sample is dried to complete the cleaning process.

[0045] Therefore, the cleaning method provided by the present invention can be used to remove particles, metal pollution and organic pollution at the same time, thereby realizing the preparation of high-purity single-crystalline gallium nitride; at the same time, it can also effectively modify the surface state of single-crystalline gallium nitride, reduce the dislocation of single-crystalline gallium nitride, and enhance the electronic conductivity of single-crystalline gallium nitride.

[0046] Embodiment 2:

[0047] like Figure 1 As shown, a method for cleaning high-purity single-crystal GaN comprises the following steps:

[0048] S1. Preparing an APM-like solvent: mixing an alkaline raw material, an oxidant raw material and water in a certain proportion to form an APM-like solvent, wherein the concentration of the alkaline raw material after preparation is 8%, and the concentration of the oxidant raw material is 25%;

[0049] Wherein, the alkaline raw material is a mixture of ammonium sulfide, ammonium hydrogen sulfide, ammonium fluoride and ammonium citrate, and the weight ratio thereof is 0.6:0.6:0.3:0.1;

[0050] The oxidant raw material is a mixture of peroxyethanol, peracetic acid and sodium borate, and the weight ratio thereof is 0.3:0.25:0.1;

[0051] S2, organic pollution removal unit and metal pollution removal: use APM-like solvent to clean the single crystal GaN, and then use APM-like solvent to rinse off the impurity components generated on the surface of the single crystal GaN during the cleaning process. The rinsing time is 10 minutes;

[0052] S3, surface state optimization: the single crystal GaN treated in step S2 is placed in an acid wash solution for acid washing for 30 minutes; the acid wash solution is a mixture of hydrofluoric acid, 2-chloroethanethiol, trifluoroacetic acid and trichloroacetic acid, and the weight ratio thereof is 0.5:0.3:0.1:0.1;

[0053] S4, surface rinsing and drying: The single crystal GaN after pickling in step S3 is rinsed with ultrapure water for 5 minutes to rinse the impurity components generated during the pickling process, and then it is vacuum dried at 100° C. for 24 hours to complete the cleaning process.

[0054] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements will not cause the essence of the corresponding technical solutions to deviate from the protection scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for cleaning high-purity single-crystal GaN, It is characterized in that The following steps are involved: S1. Preparation of APM-like solvent: mixing alkaline raw material, oxidant raw material and water in a certain proportion to form APM-like solvent, wherein the concentration of alkaline raw material after preparation is 0.001%-10%, and the concentration of oxidant raw material is 0.01%-30%; Wherein, the alkaline raw material is one or more of aluminum reagent, cupric iron reagent, ammonium sulfide, ammonium hydrogen sulfide, ammonium chloride, ammonium bromide, tetramethylammonium bromide, tetrapropylammonium bromide, tetraethylammonium bromide, hexadecyltrimethylammonium bromide, hexadecyltrimethylammonium chloride, benzyltriethylammonium bromide, ammonium fluoroborate, ammonium fluoride, ammonium formate, ammonium citrate, sodium carbonate, potassium carbonate, lithium carbonate and rubidium carbonate; The oxidant raw material is one or more of sodium borate, sodium thiosulfate, strontium peroxide, peracetic acid, peroxyethanol, sodium dichromate, chromic acid, potassium permanganate, ammonium persulfate and potassium perborate; S2, organic pollution removal unit and metal pollution removal: using APM-like solvent to clean the single crystal GaN; S3, surface state optimization: placing the single crystal GaN treated in step S2 into a pickling solution for pickling; S4, surface washing and drying: using a washing liquid to wash the single crystal GaN after pickling in step S3, washing away the impurity components generated during the pickling process, and then vacuum drying it at 60-100° C. for 10-24 hours to complete the washing process; The alkaline raw material is a mixture of ammonium sulfide, ammonium hydrogen sulfide, ammonium fluoride and ammonium citrate, and the weight ratio thereof is (0.1-0.9):(0.2-0.8):(0.05-0.3):(0.01-0.1); The oxidant raw material is a mixture of peroxyethanol, peracetic acid and sodium borate, and the weight ratio thereof is (0.2-0.7):(0.05-0.3):(0.05-0.2); After the cleaning in step S2 is completed, there is another rinsing procedure: using an APM-like solvent to rinse off the impurity components generated on the surface of the single crystal GaN during the cleaning process in step S2, and the rinsing time is 5-10 minutes.

2. A method for cleaning high-purity single-crystal GaN according to claim 1, It is characterized in that The pickling time in step S3 is 10-30 min.

3. A method for cleaning high-purity single-crystal GaN according to claim 1, It is characterized in that The pickling solution is one or more of perchloric acid solution, selenic acid solution, hydrofluoric acid solution, hydroiodic acid, hydrobromic acid, chloric acid, bromic acid, metaperiodic acid, permanganic acid, 2-chloroethanethiol, 2,4,6-trinitrophenol, trifluoroacetic acid, trichloroacetic acid, methanesulfonic acid and benzenesulfonic acid, and the concentration of the pickling solution is 0.1-45%.

4. A method for cleaning high-purity single-crystal GaN according to claim 1, It is characterized in that The pickling solution is a mixture of hydrofluoric acid, 2-chloroethanethiol, trifluoroacetic acid and trichloroacetic acid, and the weight ratio thereof is (0.1-0.5):(0.01-0.3):(0.05-0.1):(0.005-0.1).

5. A method for cleaning high-purity single-crystal GaN according to claim 1, It is characterized in that The rinsing time of step S4 is 1-10 min.

6. A method for cleaning high-purity single-crystal GaN according to claim 1, It is characterized in that The flushing liquid is one or more of ultrapure water, acetone, isopropanol and ethanol.

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