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

The objective of this research is to improve the quality of the KrF excimer laser micromachining of metal and silicon in fabricating electro-thermal-compliant (ETC) micro devices. The ETC devices combine the actuator and the mechanism into one monolithic compliant continuum and enable a range of mechanical manipulation tasks at micron scale. An efficient method for optimizing the process parameters in laser micromachining, using the orthogonal array-based experimental design method, is presented in this paper. The feed rate of the XY stage, the laser pulse frequency, the discharge voltage and the number of passes were used as the control parameters. The roughness of the machined edge was used as the primary indicator of cutting performance. The roughness of the edges was computed automatically from the optical image of the machined samples, The heat-affected zone, kerf width and rate of cutting depth (depth per one pass) were used as additional quality indicators. The orthogonal array method enabled the optimization of the control parameters by reducing the required number of experiments: compared to the traditional full factorial experiment. Furthermore, machining in a liquid environment improved the quality and eliminated more debris and recast compared to machining in the air.