HIGH SENSITIVE ABSOLUTE MEMS CAPACITIVE PRESSURE SENSOR IN SiGeMEMS PROCESS FOR BIOMEDICAL APPLICATIONS

A high sensitive CMOS Micro-electro-mechanical rectangular capacitive pressure sensor in SiGeMEMS process (Silicon Germanium Micro-electro-mechanical System process) is designed and analyzed. Polycrystalline Silicon Germanium (Poly-SiGe) having low fatigue and high strength is effectively used as the sensor diaphragm material to achieve better reliability. The designed perforated diaphragm clamped only at the short sides, yielded high sensitivity, large dynamic range and better linearity. On-chip signal processing circuit in 0.18 µm TSMC CMOS technology is designed to achieve a high single stage gain of 86 dB. A higher sensitivity of 8.72 mV/V/hPa, with a non linearity of less than 1% for the full scale range of applied pressure load is achieved. The diaphragm having a wider dynamic range of 2 hPa – 500 hPa has increased low pressure capability for pulmonary wedge pressure measurement. With the underlying design of CMOS circuitry the micro-system has a reduced chip area for implantable device application