A Modular CMOS Foundry Process for Integrated Piezoresistive Pressure Sensors

Abstract

In this paper a CMOS foundry process is presented, which allows the integration of piezoresistive pressure sensors with mixed signal electronic circuits on a single chip. Based on a 1.0μm modular CMOS technology platform, two distinct MEMS process modules have been developed. The first of these process modules is based on silicon direct wafer bonding in a pre-CMOS process and is designed for the realisation of miniature absolute pressure sensors. The second process is based on a conventional bulk micromachining post-CMOS process and allows the realisation of relative and absolute pressure sensors. Prototypes of pressure sensors have been fabricated and characterised as discrete devices. The measurements have shown that the sensors have state-of-the-art performance. A set of reliability tests have been carried out and show that the device characteristics remain stable even under harsh environmental conditions.