Realization of quartz MEMS accelerometer based on flip chip process

This research attends to provide a simple and effective way to precisely assemble a quartz MEMS accelerometer, which is composed of a double-ended tuning fork (DETF) force transducer, and a base-proof mass structure. Flip chip method is proposed to bond the two sides of DETF in length direction onto the base and proof mass structure via AuSn solder utilizing the self alignment function of reflow process. Finite element analysis method is used to design and optimize the sensor structure including the dimensions of DETF, mass proof and solder bump height and so on. The optimized accelerometer sensitivity is about 50 Hz/g at a fixed planar dimension in 4 mm × 8 mm. The DETF is fabricated on a 100 μm thick Z cut wafer and the monolithic base-proof mass structure, which is linked with a thinned flexure, is fabricated on a 300 μm thick wafer using well established quartz MEMS wet etching process.