Ultra-precision grinding of 4H-SiC wafer by PAV/PF composite sol-gel diamond wheel

Kaiping Feng,Binghai Lyu,Zhaozhong Zhou,Tianchen Zhao

doi:10.1177/16878140211044929

Kaiping Feng, Binghai Lyu + Show 2 more

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https://doi.org/10.1177/16878140211044929

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Abstract

To eliminate the deep scratches on the 4H-SiC wafer surface in the grinding process, a PVA/PF composite sol-gel diamond wheel was proposed. Diamond and fillers are sheared and dispersed in the polyvinyl alcohol-phenolic resin composite sol glue, repeatedly frozen at a low temperature of −20°C to gel, then 180°C sintering to obtain the diamond wheel. Study shows that the molecular chain of polyvinyl alcohol-phenolic resin is physically cross-linked to form gel under low-temperature conditions. Tested by mechanical property testing machines, microhardness tester, and SEM. The results show that micromorphology is more uniform, the strength of the sol-gel diamond wheel is higher, the hardness uniformity is better than that of the hot pressing diamond wheel. Grinding experiments of 4H-SiC wafer were carried out with the prepared sol-gel diamond wheel. The influence of grinding speed, feed rate, and grinding depth on the surface roughness was investigated. The results showed that by using the sol-gel diamond wheel, the surface quality of 4H-SiC wafer with an average surface roughness Ra 6.42 nm was obtained under grinding wheel speed 7000 r/min, grinding feed rate 6 µm/min, and grinding depth 15 µm, the surface quality was better than that of using hot pressing diamond wheel.

Highlights

Single crystal SiC (4H-SiC), one of the third-generation semiconductor materials, has excellent electrical and chemical properties, such as wide energy band gap, excellent thermal conductivity, high breakdown electric field, and appropriate chemical stability
Ultra-precision grinding was introduced as a semifinishing process before CMP of hard and brittle materials to reduce CMP polishing time,[9] Kim and Lee[10] found that a finer super-abrasive wheel could obtain the mirror-like grinding surface of MgO single crystals, Ren et al.[11] carried out a side grinding experiment of single-crystal silicon (100 lattice orientation) using electroplated diamond micro-grinding tools
After grinding with a sol-gel diamond wheel, the scratches formed on the surface of the wafer are slight and uniform, and the scratches can be removed by CMP polishing

Summary

Introduction

Single crystal SiC (4H-SiC), one of the third-generation semiconductor materials, has excellent electrical and chemical properties, such as wide energy band gap, excellent thermal conductivity, high breakdown electric field, and appropriate chemical stability. Keywords Sol-gel diamond wheel, 4H-SiC wafer, ultra-precision grinding, surface roughness, abrasion

Results

Conclusion