An integrated reduced micromachined inertial measurement unit for land vehicle navigation

In this paper, a reduced micromachined inertial measurement unit (MIMU) was fabricated by a two-step selective SOI release process in order to meet the requirements of land vehicle navigation. In the process, the release process consists of two steps, i.e. dry release using notching effect and wet release using HF solution. Most area of the device was released in the dry etching process, but the boundaries of the proof mass and the suspension beams were not released until the wet etching. Through such a process configuration, the poor surface roughness on the bottom side of some important structures such as suspension beams was alleviated. While, the poor roughness on the bottom side of proof mass can alleviate the stiction effectively. The test results showed that the scale factors of the X/Y-axis accelerometer and Z-axis gyroscope were about 19.11 mV/g and 15.6mV/°/s at one atmosphere, respectively. The bias stability of the gyroscope was about 123.0deg/h with a resolution of 0.0151°/s/√Hz.