Sidewall arris flatting process in quartz gyroscope fabrication

The fabrication of quartz gyroscope is studied through the quartz wet etching experiments in this paper. The quartz gyroscope is made of quartz wafer covered by Cr/Au mask in etchant and need to form electrodes on the sidewall of quartz beam. The key problem in fabrication is two steps arris in on the sidewall because of anisotropy in quartz etching. 100Å Cr and 2000Å Au films are deposited at double sides of 500μm Z-cut quartz wafer as the etch mask. The quartz etchant was a mixture of HF and NH4F in proportions HF:NH4F = 1:1. Wet etching experiments are carried out every 5°C from 50°C to 80°C. Etch rate nonlinearly increases with temperature, and high temperature makes the roughness of sidewall surface increase. After 27h etching, the two steps arris are flatted because the etch rates of main surface on the quartz sidewall are different. This flatting process has been used in the fabrication of the gyroscope.