Characterization of MEMS structure on silicon wafer using KrF excimer laser micromachining

This paper presents preliminary parametric studies of KrF laser micromachining ablation effects on Silicon. Four parameters are studied, namely laser energy, pulse rate, number of laser pulses, and Rectangular Variable Aperture (RVA) in X and Y direction. At present, the study is focused on the production of microchannels using laser micromachine, in which its dimension is examined and measured. We found that the number of laser pulse is non-linearly proportional with the ablated channel width, with the etching rate of approximately 1 to 5 um for 50 laser pulses. This is similar with the measured depth of the microchannel. The changes in the measured channel width are most significant when the laser energy is increased. Some debris and recast can also be observed around the edge of the microchannel particularly during the variation of the laser pulse frequency. When varying the RVA, it is observed that the surfaces of the ablated microchannels are not smooth with a lot of debris accumulated at the channel edge and a few discolorations. Finally, a microcantilever structure is fabricated with the aim of demonstrating the capability of the laser micromachine.