A quality study on the excimer laser micromachining ofelectro-thermal-compliant micro devices

Abstract

The objective of this research is to improve the quality of theKrF excimer laser micromachining of metal and silicon in fabricatingelectro-thermal-compliant (ETC) micro devices. The ETC devices combine theactuator and the mechanism into one monolithic compliant continuum andenable a range of mechanical manipulation tasks at micron scale. Anefficient method for optimizing the process parameters in lasermicromachining, using the orthogonal array-based experimental designmethod, is presented in this paper. The feed rate of the XY stage, thelaser pulse frequency, the discharge voltage and the number of passes wereused as the control parameters. The roughness of the machined edge wasused as the primary indicator of cutting performance. The roughness of theedges was computed automatically from the optical image of the machinedsamples. The heat-affected zone, kerf width and rate of cutting depth(depth per one pass) were used as additional quality indicators. Theorthogonal array method enabled the optimization of the control parametersby reducing the required number of experiments compared to the traditionalfull factorial experiment. Furthermore, machining in a liquid environmentimproved the quality and eliminated more debris and recast compared tomachining in the air.