Geometric Compensation of (100) SCS Vibrating Ring Gyroscope for Mode-Matching Achieving High Immunity to Fabrication Imperfections

This paper reports a geometric compensation method that utilizes cascaded "Christmas Tree-like" spring beams (CTRG) to reduce the initial frequency split of a vibrating ring gyroscope fabricated with (100) single crystal silicon (SCS). The CTRG effectively compensate the anisotropy in Young's modulus of (100) SCS that deteriorates mode-matching, and the frequency split achieves high immunity to fabrication imperfections due to series springs. Compared with the devices made of (111) SCS, the gyroscopes fabricated with (100) SCS using geometric compensation are easier to realize single chip CMOS integration. The results show that the initial frequency split of a 10.5 kHz CTRG ring gyroscope is reduced from 303.2Hz to 5.2Hz on average among 30 samples. The minimum split reaches 2.3Hz (0.022%), which is even better than the devices fabricated with isotropic materials.