Micromachined Electrodes for High Performance Capacitive Pressure Sensors

This report discusses the use of silicon micromachining to create a part for subassembly into a high performance capacitive pressure sensor. The micromachined silicon part replaces traditionally machined metal parts. The micromachined parts provide tight control of the gap between the electrode of the pressure sensor and the membrane, which improves the uniformity of the characteristics of the pressure sensor across the production line. The capacitive pressure sensor is discussed initially. A detailed review of the design, considerations and process flow are given. The process mainly relies on the use of deep reactive ion etching (DIRE) to machine the backplates out of silicon wafers. Finally, we examine the major issues involved and the future possibilities afforded by using silicon in such a manner.