Application of a Femtosecond Laser in the Fabrication fused Silica Sensing Elements for MEMS Accelerometers

A group method of manufacturing quartz sensing elements of MEMS Q-flex type accelerometers is known, which is based on sequential liquid and plasma chemical etching in fluorinated plasma. In order to reduce the defects of the final products, labor costs for their manufacture and to obtain a rectangular etching profile of through holes in the section of the sensing element, an alternative technology for forming holes has been developed. The technology is thus the laser radiation pretreatment of fused silica glass with ultrashort pulse duration (about hundreds of femtoseconds) for the entire thickness of the substrate and subsequent liquid etching holes. The conducted studies revealed a local increase in the etching rate of irradiated section of fused silica glass during liquid etching with hydrofluoric acid or alkaline solution. The influence of the etching solution concentration on the change in the etching rate and the roughness of quartz is analyzed. The technology is universal and it can be used for high-precision volumetric processing of product formed from fused silica glass up to 4 mm thick.