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Growth method for reducing density of micro-tubes in large-sized high-quality SiC single crystal

A growth method and high-quality technology, applied in the direction of single crystal growth, single crystal growth, crystal growth, etc., can solve the problems of new microtube generation, low density of single crystal microtubes, etc., and achieve the effect of reducing the total number of microtubes

Active Publication Date: 2014-02-19
SHANDONG UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Therefore, in the micropipes in a crystal with many defects and a large number of defects, the stress generated by the micropipes can be released through other defects, and the stress is relaxed. Therefore, the stress caused by the lattice distortion caused by doping elements may cause new microtubules
In recent years, with the in-depth study of the formation mechanism of various defects during the growth of SiC single crystals, and the use of various methods to eliminate defects such as carbon inclusions, silicon droplets, voids, and polytypes, the quality of SiC crystals has been greatly improved. Quasi-perfect crystals, and have achieved certain application results, but there are still a certain number of micropipes in quasi-perfect crystals, and it is currently a technical problem to minimize the density of single-crystal micropipes, or even reach the level of zero micropipes.

Method used

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  • Growth method for reducing density of micro-tubes in large-sized high-quality SiC single crystal
  • Growth method for reducing density of micro-tubes in large-sized high-quality SiC single crystal
  • Growth method for reducing density of micro-tubes in large-sized high-quality SiC single crystal

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Experimental program
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Effect test

Embodiment 1

[0031] In the SiC single crystal furnace, the SiC single crystal is grown by the sublimation method, and the size of the grown single crystal is 3 inches by induction heating. The SiC powder is placed in the lower part of the graphite crucible, the SiC seed crystal is placed in the upper part of the crucible, and a certain distance is kept between the SiC seed crystal and the SiC powder.

[0032] Before growth, first vacuum to remove impurities, so that the vacuum degree of the growth chamber reaches 10 -4 Pa. The size of the seed plane used is 3 inches, the growth plane is a carbon plane, and the growth direction is along the c-axis [0001] direction. The micropipe defect density of the seed crystal is 4.5 / cm 2 . During growth, the growth pressure was 5 mbar, the temperature of the upper cover of the crucible was 2100 °C, the nucleation rate was controlled at 10 μm / h, and the temperature gradient in the axial direction was controlled at 50 °C / mm. After 20 h of growth, high...

Embodiment 2

[0039] A method for reducing the density of micropipes in high-quality SiC crystals, as described in Example 1, the difference is that before growth, the vacuum is evacuated until the vacuum degree reaches 10 -3 Pa. During growth, the growth pressure is 50 mbar, the temperature of the crucible cover is 2400 °C, the nucleation rate is controlled at 500 μm / h, and the temperature gradient in the axial direction is controlled at 200 °C / mm. After 22 hours of growth, high-purity nitrogen gas was introduced into the growth chamber for 2 hours at a flow rate of 5 sccm. The growth time is 60h, and after the growth, the cooling rate is 40°C / h. After three generations of cyclic growth, the result was the same as in Example 1.

Embodiment 3

[0041] A method for reducing the density of micropipes in high-quality SiC crystals, the specific method is the same as in Example 1, the difference is that before the growth, the vacuum is evacuated until the vacuum degree reaches 10 -2 Pa. During growth, the growth pressure was 45 mbar, the temperature of the upper cover of the crucible was 2200 °C, the nucleation rate was controlled at 220 μm / h, and the temperature gradient in the axial direction was controlled at 150 °C / mm. After growing for 24 hours, high-purity nitrogen gas was passed through the growth chamber for 10 hours at a flow rate of 10 sccm. The growth time is 100h, and after the growth, the cooling rate is 100°C / h. After three generations of cyclic growth, the result was the same as in Example 1.

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Abstract

The invention relates to a growth method for reducing density of micro-tubes in a large-sized high-quality SiC single crystal. A sublimation method is used in a SiC single crystal furnace to grow the SiC single crystal, the air is vacuumized to 10<-4> Pa-10<-2> Pa before growth, the growth pressure is 5-50 mbar, the temperature is 2100-2400 DEG C, the rate is 10-500 mum / h, high-purity nitrogen is introduced into a growth chamber for 2-10 hours when the crystal grows for 20-24 hours, the same nitrogen is introduced again after an interval of 20 hours, the process is periodically repeated to obtain the intermittently nitrogen-doped SiC single crystal, the obtained SiC single crystal does not have the defects of cavity, silicon drop, polytype and the like, and the density of the micro-tubes is greatly reduced. The growth method achieves the objectives of reducing the density of the micro-tubes to the lowest and even to the level of zero micro-tube.

Description

technical field [0001] The invention relates to a method for reducing the density of micropipes in large-size and high-quality SiC single crystals, and belongs to the technical field of artificial crystal materials. Background technique [0002] SiC is the third-generation wide bandgap semiconductor material developed after Si and GaAs. SiC has high breakdown field strength, high thermal conductivity, high saturation electron mobility, good physical and chemical stability, and is ideal for manufacturing high-temperature, high-power , High voltage, high frequency semiconductor device ideal material. At present, a variety of SiC electronic devices have been commercialized, such as P-i-N diodes, Schottky diodes, MESFETs, MOSFETs, thyristors, etc. [0003] At present, there are still some defects in the large-size SiC bulk single crystal grown by the sublimation method, such as micropipes, dislocations, polytype inclusions, etc., especially the existence of micropipe defects, w...

Claims

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Application Information

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IPC IPC(8): C30B27/00C30B29/36C30B29/60
Inventor 陈秀芳徐现刚彭燕胡小波
Owner SHANDONG UNIV
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