A modular process for integrating thick polysilicon MEMS devices with sub-micron CMOS

A new MEMS process module, called Mod MEMS, has been developed to monolithically integrate thick (5-10um), multilayer polysilicon MEMS structures with sub-micron CMOS. This process is particularly useful for advanced inertial MEMS products such as automotive airbag accelerometers where reduced cost and increased functionality is required, or low cost, high performance gyroscopes where thick polysilicon (>6um) and CMOS integration is required to increase poly mass and stiffness, and reduce electrical parasitics in order to optimize angular rate sensing. In this paper we will describe the new modular process flow, development of the critical unit process steps, integration of the module with a foundry sub-micron CMOS process, and provide test data on several inertial designs fabricated with this process.