Micromachining of silicon wafer and pyrex glass with excimer laser

Laser micromachining of silicon wafer and Pyrex glass was attempted with KrF excimer laser. Effect was investigated on machining efficiency and accuracy of pulse energy, pulse repetition, atmosphere etc. Aluminum deposited metal mask was used for structuring. Etching quality with this mask was proved to be insufficient because of its low contrast. Aspect ratio obtained here was 1.5 in 15 microns of line and space structure. Penetrating etching through wafer with sufficient accuracy could be attained in silicon etching in Nitrogen gas atmosphere for 50 microns of line and space structure. This method provides a powerful technique for post release process of micro devices and three dimensional micro structuring. On the other hand, the method to avoid undercut or tipping of the bottom glass surface was developed. 300 microns of hole could be drilled successively for Imm thickness of Pyrex glass and an electrical contact test was done after anodic bonding Pyrex glass to silicon wafer. This technique provides an efficient technology to make electrical feed trough for micro devices such as pressure sensor, accelerometer, etc.