355Nm DPSS UV laser micromachining of single-crystal silicon

In recent years, laser micromachining of semiconductor materials such as silicon and sapphire has attracted more and more attention. High power Diode Pumped Solid State (DPSS) UV lasers have been gained wider application in microelectronics, flat panel display, and solar cell manufacturing industries because it can obtain smaller feature sizes, higher throughput and lower costs. In this paper, the experiments of percussion drilling and etching were carried out on single-crystal silicon by a 355nm Nd:YVO₄ laser to investigate the etching accuracy of both single layer and multilayer scanning depth with different laser processing modes and parameters in order to meet the technologic requirement of laser micromachining. The effects of the parameters (average power, repetition rate, scanning speed and scan spacing) on the etching quality of both single-layer and multilayer scanning depth were investigated and analysed. The mechanism of laser etching was also discussed. Some planar structures were processed on the Si surface by the optimal parameters. And then, 3D structures such as quadrangular frustum pyramid and hemisphere were manufactured by using new methods. The experimental results show that the quality with smaller thermal damage zones, less spatters and no cracks could be achieved by laser multi scan etching mode with high scanning speed, and a UV laser micro-processing system designed and developed by ourselves could directly create real 2-D and 3-D structures on the surface of silicon wafer.