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Surface polishing method for GaN monocrystal substrate

A technology of polishing disk and polishing liquid, which is applied in the field of polishing, can solve problems such as V-shaped pits, large surface fluctuations, and crystal orientation selection, and achieve the effects of low pressure, low scratch density, and high polishing efficiency

Inactive Publication Date: 2013-05-22
SHANGHAI INST OF MICROSYSTEM & INFORMATION TECH CHINESE ACAD OF SCI
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Most of the GaN growth surfaces obtained by the above method have problems such as large surface undulations, V-shaped pits, and crystal orientation selection, and usually cannot be used directly, and GaN crystals need to be cut and polished.

Method used

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  • Surface polishing method for GaN monocrystal substrate

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0025] (1) Cut and orient the GaN crystal, and perform mechanical grinding on it. After grinding, the crystal plane of the GaN crystal is 0.6° from c to m plane, the thickness tolerance is less than 10 μm, and the root mean square of surface roughness is about 1-2.5nm .

[0026] (2) Wash the finely polished GaN with acetone, ethanol, and deionized water in sequence to remove oil stains on the back and surface, and then dry it with nitrogen gas for later use.

[0027] (3) Use thermoplastic conductive adhesive (paraffin: rosin: graphite = 1: 1.5: 0.2) to fix the cleaned GaN crystal on the metal polishing compact to ensure that the conductive adhesive coating on GaN is even and smooth.

[0028] (4) Use NaOH solution with a pH value of 9.5-11.5 as the polishing liquid.

[0029] (5) The GaN crystal is used as the anode to connect to the positive pole of the DC power supply, and the tin polishing disc is used as the cathode to connect to the negative pole of the DC power supply, an...

Embodiment 2

[0033] (1) Cut and orient the GaN crystal, and perform mechanical grinding on it. After grinding, the crystal plane of the GaN crystal is c-plane, the thickness tolerance is less than 20 μm, and the surface roughness root mean square is about 1-2.5 nm.

[0034] (2) Wash the finely polished GaN with acetone, ethanol, and deionized water in sequence to remove oil stains on the back and surface, and then dry it with nitrogen gas for later use.

[0035] (3) Use thermoplastic conductive adhesive (paraffin: rosin: graphite = 1: 1.5: 0.2) to fix the cleaned GaN crystal on the metal polishing compact to ensure that the conductive adhesive coating on GaN is even and smooth.

[0036] (4) Use a citric acid solution with a pH of 3.8-4.6 as the polishing fluid.

[0037] (5) The GaN crystal is used as the anode to connect to the positive pole of the DC power supply, and the tin polishing disc is used as the cathode to connect to the negative pole of the DC power supply. The output current ...

Embodiment 3

[0041] (1) Cut and orient the GaN crystal, and mechanically grind it. After grinding, the crystal plane of the GaN crystal is the c-plane, the thickness tolerance is less than 20 μm, and the root mean square of the surface roughness is about 1-2.5 nm.

[0042] (2) Wash the finely polished GaN with acetone, ethanol, and deionized water in sequence to remove oil stains on the back and surface, and then dry it with nitrogen gas for later use.

[0043] (3) Use thermoplastic conductive adhesive (paraffin: rosin: graphite = 1: 1.5: 0.2) to fix the cleaned GaN crystal on the metal polishing compact to ensure that the conductive adhesive coating on GaN is even and smooth.

[0044] (4) Use a 10wt% aqueous solution of silicon dioxide with a particle size of 50nm, adjust the pH to 9.5-11.5, and add a small amount of EDTA as a polishing solution.

[0045] (5) The GaN crystal is used as the anode to connect to the positive pole of the DC power supply, and the tin polishing disc is used as ...

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Abstract

The invention provides an electrochemical mechanical polishing method for a gallium nitride monocrystal substrate, which comprises the following steps: by using a gallium nitride crystal and a polishing disk respectively as an anode and a cathode, mechanically lapping the GaN crystal, and carrying out electrochemical mechanical polishing in an electrolyte. The invention can obtain a flatness with the surface roughness root mean square of less than 0.5nm on the surface of the GaN crystal. The invention has the advantages of high polishing efficiency and low scratch density. The invention does not need to use strong acid or strong alkali as a polishing solution, can be performed at normal temperature, is simple and easy to implement, and is applicable to industrial production.

Description

technical field [0001] The invention belongs to the field of polishing methods, in particular to a surface polishing method for a GaN single crystal substrate. technical background [0002] The third-generation semiconductor material represented by GaN is one of the most important wide bandgap semiconductor materials. Their unique bandgap range, excellent optical and electrical properties and excellent material mechanical properties make them suitable for light-emitting devices from blue-green to ultraviolet bands, ultraviolet detectors, outer space and submarine communications, electronic devices and special conditions. Semiconductor devices and other fields have broad application prospects. [0003] The fabrication of GaN devices is restricted by epitaxial substrates. Usually, GaN-based devices are mainly heterogeneously epitaxial on single crystal substrates such as sapphire and SiC. The huge lattice mismatch and thermal mismatch between the substrate and the epitaxial ...

Claims

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Application Information

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IPC IPC(8): C25F3/12C25F3/30B24B37/00C30B33/00C30B33/10
Inventor 王斌
Owner SHANGHAI INST OF MICROSYSTEM & INFORMATION TECH CHINESE ACAD OF SCI
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