A CMOS compatible process for monolithic integration of high-aspect-ratio bulk silicon microstructures

Abstract

We report a CMOS compatible bulk micromachining method for the integration of high-aspect- ratio single crystal silicon MEMS (micro electromechanical systems) devices and signal conditioning circuit on a standard silicon wafer. The trench refilling and residual silicon removing techniques are used to acquire a proper electrical insulation between the different actuation and sensing elements situated on either fixed or movable parts of an MEMS device. To demonstrate the compatibility of the process, an integrated MEMS accelerometer was implemented. Test results show that the resistance between different elements of the device is larger than 10 12 Ω. The electrical properties of the transistors that experienced MEMS fabrication agree well with those without MEMS process, indicting the CMOS compatibility of the process.