A CMOS integrated MEMS capacitive pressure sensor design in a 3D SiGeMEMS process

A novel CMOS integrated Micro-Electro-Mechanical capacitive pressure sensor in SiGeMEMS (Silicon Germanium Micro-Electro-Mechanical System) process is designed and analyzed. Excellent mechanical stress-strain behavior of Polycrystalline Silicon Germanium (Poly-SiGe) is utilized effectively in this MEMS design to characterize the structure of the pressure sensor diaphragm element. The edge clamped elliptic structured diaphragm uses semi-major axis clamp springs to yield high sensitivity, large dynamic range and good linearity. Integrated on-chip signal conditioning circuit in 0.18μm TSMC CMOS technology (forming the host substrate base for the SiGe MEMS) is also implemented to achieve a high gain of 100.5dB for the MEMS sensor. A high sensitivity of 4.65mV/V/hPa, with a non linearity of less than 1% for the full scale range of applied pressure load is achieved. The diaphragm with a wide dynamic range of 10hPa - 1000hPa stacked on top of the CMOS circuitry, effectively reduces the combined sensor+conditioning implementation area of the intelligent sensor chip.