飞秒激光抛光6H碳化硅硅面实验研究

Experimental Study on 6H Silicon Carbide Silicon-Face Polished by Femtosecond Laser

摘要: 6H碳化硅(6H-SiC)作为目前应用最广的第三代半导体材料，其加工制造过程面临工艺步骤繁琐、研磨后表面质量缺陷严重等难题。本研究提出采用飞秒激光方法直接抛光SiC切割片，考察了激光重复频率、扫描间距、脉冲能量、扫描速度、离焦距离等工艺参数对抛光后SiC表面质量的影响。结合扫描电镜(SEM)、能量色散X射线光谱仪(EDX)、激光共聚焦显微镜对抛光后表面形貌、结构、成分等表征，分析了表面质量的影响因素。研究发现在激光重复频率为15 kHz、扫描间距15 μm、脉冲能量89.3 μJ、扫描速度118 mm/s、离焦 + 1 mm抛光后6H-SiC硅面表面粗糙度(Ra)由0.457 μm降低至0.116 μm，表面起伏(Depth)由3.8 μm降低至0.77 μm。本研究对于优化6H-SiC硅面制造工艺，提高加工效率具有较大的参考价值。

Abstract: 6H silicon carbide (6H SiC) is the widely used third-generation semiconductor material at present. Its manufacturing process faces many problems, such as complicated process steps, serious surface quality defects after grinding and so on. In this study, the femtosecond laser is used to polish the SiC silicon-face after cutting directly. Influence of laser repetition frequency, scanning interval, pulse energy, scanning speed, defocus distance and other process parameters on the surface quality of the polished SiC are investigated. The impacts of surface quality are analyzed by SEM, EDX and laser confocal microscope. The results show that the surface roughness (Ra) of 6H SiC silicon-face decreases from 0.457 μm to 0.116 μm, and the surface undulation (Depth) decreases from 3.8 μm to 0.77 μm after laser polishing with repetition frequency of 15 kHz, scanning distance of 15 μm, pulse energy of 89.3 μJ, scanning speed of 118 mm/s, defocusing + 1 mm. This study has great reference value for optimizing the manufacturing process of 6H SiC silicon-face and improving its machining efficiency.