Method for repairing gallium nitride finished single crystal with local defects

Abstract

The invention discloses a method for repairing a gallium nitride finished single crystal with local defects, and belongs to the field of gallium nitride single crystal substrate manufacturing. According to the principle that free energy required by corrosion is reduced due to local energy in a local defect area of a gallium nitride finished product single crystal material relative to a normal area, a chemical agent or a high-temperature atmosphere is adopted to carry out directional corrosion treatment on a defect part in a defective area, and hydride vapor phase epitaxy (HVPE) equipment is put again to carry out remelting epitaxy for 0-100 microns; the corroded area is healed again, the defective area is repaired after grinding and polishing, and the finished single crystal is prepared. According to the method, only the surface of the defective single crystal needs to be repaired by growing 0-100 microns, and compared with the method for preparing the finished single crystal by re-growing 700 microns of thickness, the cost can be greatly reduced, and the product yield can be improved.

Description

Technical Field

[0001] The invention belongs to the field of gallium nitride single crystal substrate production, and in particular relates to a method for repairing a locally defective gallium nitride finished single crystal. Background Art

[0002] In the process of preparing gallium nitride single crystals using the HVPE method, due to local flow field perturbations, particle falling, and large local 5:3 ratio differences, local dislocation anomalies in the finished single crystal are very likely to occur. To prepare a single piece of 400 μm thick finished gallium nitride single crystal using the HVPE method, it is necessary to grow at least 700 μm, and only after grinding and polishing can a 400 μm thick finished single crystal be obtained. In the process of this type of finished single crystal flow-through to chip manufacturing, the blue-green laser manufactured using this area has very poor laser quality (output power, service life, etc.) compared with the normal area, and in more serious cases, it is even directly non-conductive. Therefore, in actual production control, such locally abnormal gallium nitride single crystals are judged as scrapped pieces and cannot be used. Such local anomalies lead to the scrapping of the entire finished gallium nitride single crystal, which is one of the most important reasons for the high cost of gallium nitride single crystals. Summary of the invention

[0003] In view of the above problems, the present invention proposes a method for repairing a locally defective GaN finished single crystal. The method utilizes the principle that the local energy in the local defective area of ​​the GaN finished single crystal material relative to the normal area reduces the free energy required for corrosion, and the defective area is etched with a specific ratio of liquid or high-temperature atmosphere, and then returned to the furnace for re-epitaxial growth, thereby achieving a method of eliminating local defects.

[0004] In order to achieve the above object, the present invention adopts the following technical solution: A method for repairing a locally defective GaN finished single crystal comprises the following steps: firstly subjecting the locally defective GaN finished single crystal to a directional etching treatment using an etching solution or a high-temperature atmosphere, then placing the finished single crystal into an HVPE device for remelting and epitaxy to heal the corroded area, and finally repairing the defective area after grinding and polishing.

[0005] The etching solution is one or more of phosphoric acid, nitric acid, hydrogen peroxide, sodium hydroxide, hydrofluoric acid, sulfuric acid, hydrochloric acid, and buffered oxide etching solution.

[0006] The gas used in the high temperature atmosphere is one or more of H2, N2, O2, HCl, Cl2 or BCl3.

[0007] The thickness of the melt-down epitaxy is 0-100 μm.

[0008] The etching solution is a mixture of phosphoric acid and hydrogen peroxide in a volume ratio of 1:1. The finished single crystal of gallium nitride with local defects is placed in the etching solution and etched at 180° C. for 40 minutes. The etching depth is 20-100 μm, preferably 20-40 μm.

[0009] The etching solution comprises an etching solution A and an etching solution B, wherein the etching solution A is obtained by mixing sulfuric acid, hydrogen peroxide and deionized water in a volume ratio of 5:1:1, and the etching solution B is obtained by mixing hydrochloric acid, hydrogen peroxide and deionized water in a volume ratio of 1:1:5. The finished gallium nitride single crystal with local defects is first placed in the etching solution A and is corroded at a temperature of 180°C for 40 minutes; then placed in the etching solution B and corroded at 100°C for 20 minutes, and the corrosion depth is 20-100 μm, preferably 20-40 μm.

[0010] The gases of the high temperature atmosphere are N2, HCl, and H2, with flow rates of 15000 sccm, 200 sccm, and 8000 sccm, respectively. The etching temperature is 1080°C, the pressure is 500 torr, the etching time is 30 min, and the etching depth is 30-100 μm.

[0011] The gases of the high temperature atmosphere are O2, Cl2, and BCl3, with flow rates of 10 sccm, 100 sccm, and 5 sccm, respectively. The etching temperature is 100°C, the pressure is 10 torr, the etching time is 60 min, and the etching depth is 30-100 μm.

[0012] The finished gallium nitride single crystal is prepared by the above repair method.

[0013] The beneficial effects of the present invention are: By using chemical agents or high-temperature atmosphere to etch the defective area, and then returning to the furnace for re-epitaxial growth, the corrosion depth of the defective area can be controlled to 0-100 μm, and only the corrosion area needs to be filled during the re-epitaxial growth. That is, according to the depth of the corrosion pit, only 0-100 μm of single crystal surface needs to be grown to repair the defect using this method. Compared with re-growing 700 μm thick single crystals to prepare finished products, this can significantly reduce costs and improve product yields. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 This is a local area diagram of the finished GaN single crystal; Figure 2 The present invention is a flow chart of a method for repairing a locally defective GaN finished single crystal; Figure 3 This is a dislocation abnormal area diagram of a locally dislocated single crystal of a locally defective gallium nitride finished single crystal in Example 1; Figure 4This is a regional diagram of a locally dislocated single crystal after using the method for repairing a locally defective gallium nitride finished single crystal in Example 1; Figure 5 This is a dislocation abnormal region diagram of a locally dislocated single crystal of a locally defective gallium nitride finished single crystal in Example 2; Figure 6 This is a regional diagram of a locally dislocated single crystal after using the method for repairing a locally defective gallium nitride finished single crystal in Example 2; Figure 7 This is a dislocation abnormal region diagram of a locally dislocated single crystal of a locally defective gallium nitride finished single crystal of Example 3; Figure 8 This is a regional diagram of a locally dislocated single crystal after being repaired using the method for repairing a locally defective gallium nitride finished single crystal according to Example 3. DETAILED DESCRIPTION

[0015] The present invention will be further described below in conjunction with the accompanying drawings and examples. It should be noted that the following detailed description is illustrative and is intended to provide further explanation of the present application. Unless otherwise specified, all technical and scientific terms used herein have the same meanings as those generally understood by those of ordinary skill in the art to which the present application belongs.

[0016] A method for repairing a locally defective GaN finished single crystal, specifically, adding a chemical agent or a high-temperature atmosphere etching step to the traditional steps of crystal preparation. The local area of ​​the GaN finished single crystal is shown in FIG. Figure 1 The repair process is as shown in Figure 2 shown.

[0017] Example 1 A method for repairing a locally defective GaN finished single crystal, the specific steps are as follows: (1) Screening out GaN finished single crystals with local dislocation defects; (2) Phosphoric acid (concentration 85%-87%) and hydrogen peroxide (30%-32%) are mixed in a volume ratio of 1:1 to obtain a corrosion solution; (3) placing the selected GaN single crystal with local dislocation defects into the above-mentioned etching solution and etching at 180°C for 40 min to a depth of 20-40 μm; (4) After washing and drying the sample obtained in step (3), the sample was placed in an HVPE device for epitaxial growth of 0-100 μm GaN. The specific epitaxial thickness was determined according to the corrosion depth, and the epitaxial thickness was slightly greater than the corrosion depth. The epitaxial parameters were: temperature 1010°C, pressure 300 torr, flow rate: N2 (14000 sccm) + HCl (150 sccm) + H2 (8000 sccm) + NH3 (7500 sccm).

[0018] (5) The surface-repaired substrate obtained in step (4) is ground and polished to produce a finished gallium nitride single crystal.

[0019] Example 2 A method for repairing a locally defective GaN finished single crystal, the specific steps are as follows: (1) Screening out GaN finished single crystals with local dislocation defects; (2) Sulfuric acid (concentration 95%-98%), hydrogen peroxide (30%-32%) and deionized water are mixed in a volume ratio of 5:1:1 to obtain etching solution A; hydrochloric acid (35%-37%), hydrogen peroxide (30%-32%) and deionized water are mixed in a volume ratio of 1:1:5 to obtain etching solution B; (3) The selected GaN single crystal with local dislocation defects is first placed in the above-mentioned etching solution A and corroded at 180°C for 40 minutes, and then the single crystal after the above etching is placed in the etching solution B and corroded at 100°C for 20 minutes, with the etching depth of 20-40 μm; (4) After washing and drying the sample obtained in step (3), the sample is put into a HVPE device for epitaxy of 0-100 μm. The specific epitaxy thickness is determined according to the corrosion depth. The epitaxy thickness is greater than the corrosion depth. The epitaxy parameters are the same as those in Example 1. (5) The surface-repaired substrate obtained in step (4) is ground and polished to produce a finished single crystal.

[0020] Example 3 A method for repairing a locally defective GaN finished single crystal, the specific steps are as follows: (1) Screening out GaN finished single crystals with local dislocation defects; (2) The single crystal selected in step (1) is placed in a vacuum device and a mixed gas of N2, HCl and H2 is introduced at flow rates of 15000 sccm, 200 sccm and 8000 sccm, respectively; the temperature is 1080°C and the pressure is maintained at 500 torr; the etching time is 30 min; the etching depth is 50 μm; after the etching is completed, the substrate is cleaned; (3) After washing and drying the sample obtained in step (2), the sample was placed in a HVPE device for epitaxy of 60 μm, and the epitaxy parameters were the same as those in Example 1; (4) The surface-repaired substrate obtained in step (4) is ground and polished to produce a finished single crystal.

[0021] Example 4 A method for repairing a locally defective GaN finished single crystal, the specific steps are as follows: (1) Screening out GaN finished single crystals with local dislocation defects; (2) Place the single crystal selected in step (1) into a vacuum device and introduce a mixed gas of O2, Cl2, and BCl3 at flow rates of 10 sccm, 100 sccm, and 5 sccm, respectively; the temperature is 100°C and the pressure is maintained at 10 torr; the etching time is 60 min; the etching depth is 10 μm; after the etching is completed, the substrate is cleaned; (3) After washing and drying the sample obtained in step (2), the sample was placed in a HVPE device for epitaxy of 20 μm, and the epitaxy parameters were the same as those in Example 1; (4) The surface-repaired substrate obtained in step (3) is ground and polished to produce a finished single crystal.

[0022] Figure 3 This is the abnormal dislocation area of ​​the finished single crystal with local defects in Example 1. The dislocations cannot be counted. Figure 4 This is the repaired regional image, with a dislocation of 2.12×10 6 / cm 2 .

[0023] Figure 5 This is the abnormal dislocation area of ​​the finished single crystal with local defects in Example 2. The dislocations cannot be counted. Figure 6 This is the image of the repaired area, with a dislocation of 1.25×10 6 / cm 2 .

[0024] Figure 7 This is the abnormal dislocation area of ​​the finished single crystal with local defects in Example 2. The dislocations cannot be counted. Figure 8 This is the image of the repaired area, with a dislocation of 1.31×10 6 / cm 2 .

[0025] The above contents are further detailed descriptions of the present invention in combination with specific preferred embodiments, and it cannot be determined that the specific implementation of the present invention is limited to these descriptions. For ordinary technicians in the technical field to which the present invention belongs, several simple deductions or substitutions can be made without departing from the concept of the present invention, which should be regarded as falling within the protection scope of the present invention.

Claims

1. A method for repairing a locally defective GaN finished single crystal, characterized in that: The finished GaN single crystal with local defects is first subjected to directionally etching treatment using a corrosive solution or a high-temperature atmosphere, then put back into the HVPE equipment for epitaxy to heal the corroded area, and finally the defective area is repaired by grinding and polishing.

2. The method for repairing a locally defective GaN finished single crystal according to claim 1, characterized in that: The etching solution is one or more of phosphoric acid, nitric acid, hydrogen peroxide, sodium hydroxide, hydrofluoric acid, sulfuric acid, hydrochloric acid, and buffered oxide etching solution.

3. The method for repairing a locally defective GaN finished single crystal according to claim 1, characterized in that: The gas used in the high temperature atmosphere is one or more of H2, N2, O2, HCl, Cl2 or BCl3.

4. The method for repairing a locally defective GaN finished single crystal according to claim 1, characterized in that: The thickness of the melt-down epitaxy is 0-100 μm.

5. The method for repairing a locally defective GaN finished single crystal according to claim 1, characterized in that: The etching solution is obtained by mixing phosphoric acid and hydrogen peroxide in a volume ratio of 1:

1. The finished single crystal of gallium nitride with local defects is placed in the etching solution and the etching time is 40 minutes at 180° C. The etching depth is 20-100 μm.

6. The method for repairing a locally defective GaN finished single crystal according to claim 1, characterized in that: The etching liquid comprises an etching liquid A and an etching liquid B, wherein the etching liquid A is obtained by mixing sulfuric acid, hydrogen peroxide and deionized water in a volume ratio of 5:1:1, and the etching liquid B is obtained by mixing hydrochloric acid, hydrogen peroxide and deionized water in a volume ratio of 1:1:5; a finished gallium nitride single crystal with local defects is first placed in the etching liquid A and is corroded at a temperature of 180°C for 40 minutes; and then placed in the etching liquid B and corroded at 100°C for 20 minutes, with a corrosion depth of 20-100 μm.

7. The method for repairing a locally defective GaN finished single crystal according to claim 1, characterized in that: The gases of the high temperature atmosphere are N2, HCl, and H2, with flow rates of 15000 sccm, 200 sccm, and 8000 sccm, respectively. The etching temperature is 1080°C, the pressure is 500 torr, the etching time is 30 min, and the etching depth is 30-100 μm.

8. The method for repairing a locally defective GaN finished single crystal according to claim 1, characterized in that: The gases of the high temperature atmosphere are O2, Cl2, and BCl3, with flow rates of 10 sccm, 100 sccm, and 5 sccm, respectively. The etching temperature is 100°C, the pressure is 10 torr, the etching time is 60 min, and the etching depth is 30-100 μm.

9. A finished gallium nitride single crystal prepared by the repair method according to any one of claims 1 to 8.

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