基于157nm激光的GaN外延片激光抛光和划片工艺研究

Polishing and Scribing Technique of GaN Wafers Using 157 nm Laser

157 nm准分子激光的刻蚀精度高,热影响区极小,是较为理想的半导体材料微加工手段之一。通过大量实验对比,分析157 nm激光对GaN外延片抛光和划片加工过程中,各工艺参数对加工质量的影响。实验结果表明,157 nm激光抛光GaN外延片时,被刻蚀面单位面积累计辐射能量在一定范围内,会得到较好的表面粗糙度(Ra值约20 nm)。157 nm激光用于划片加工时,切槽内辐射的能量越高,残留物质越少,槽加工得越深,两侧壁面也更为陡峭;另外在扫描加工过程中适当地移动工作台高度,可以获得更好的加工效果。

157 nm excimer laser is an ideal micromachining tool of semiconductors with advantages of high preci- sion and minimal heat affected zone. In this paper, 157 nm laser is used for polishing and scribing of GaN（ Gallium Nitride） wafers, and influences of the process parameters on micromachining performance are analyzed. For laser polishing , a better surface roughness would be obtained （ about 20 nm Ra ） when the accumulated radiation energy is set within a certain range. For laser scribing of GaN wafer, the higher the radiation energy given, the deeper the groove obtained, and the sharper the side-wall formed. Besides, the appropriate shift of the table height is favorable to improve the scribing quality.