A Novel X-Axis Tuning Fork Gyroscope with "8 Vertical Springs-Proofmass" Structure on (111)-Silicon

TL;DR

This paper introduces a new x-axis MEMS gyroscope with an innovative '8 vertical springs-proofmass' structure on (111)-silicon, offering improved stability, larger capacitance variation, and lower mechanical noise for better Coriolis effect detection.

Contribution

The paper presents a novel gyroscope design with a unique vertical spring structure and precise fabrication techniques that enhance stability and sensitivity over traditional designs.

Findings

Sensitivity of 0.15mV/(deg/s)

Rate resolution around 0.1deg/s

Less than 30 Hz mismatch before tuning

Abstract

A novel x-axis tuning fork MEMS gyroscope with "8 vertical springs-proofmass" structure for Coriolis effect detection is presented. Compared with the common single-plane springs, the 8 vertical springs, symmetrically located at the top and bottom sides, more stably suspend the large thick proofmass featuring large capacitance variation and low mechanical noise. A bulk-micromachining technology is applied to obtain the large proofmass and twins-like dual beams. During the fabrication process, the dimensions of the 8 vertical springs are precisely confined by thermal oxide protected limit trenches (LTs) sidewalls and the extreme slowly etched (111)-planes; therefore a small mismatch of less than 30 Hz is achieved before tuning. Initial test shows a sensitivity of 0.15mV/(deg/s) and rate resolution around 0.1deg/s under atmosphere pressure.