An SOI-Structured Piezoresistive Differential Pressure Sensor with High Performance.

Area of Science:

• Microelectromechanical Systems (MEMS)
• Solid-State Sensors
• Semiconductor Device Physics

Background:

• Low-pressure sensing requires highly sensitive and stable devices.
• Traditional pressure sensors face challenges in miniaturization and high-temperature operation.
• Silicon-on-insulator (SOI) technology offers advantages for sensor fabrication.

Purpose of the Study:

• To design and fabricate a high-sensitivity piezoresistive differential pressure sensor using SOI technology.
• To achieve reliable low-pressure detection (0-30 kPa) with enhanced temperature stability.
• To explore the potential of SOI for miniaturized, high-performance MEMS pressure sensors.

Main Methods:

• Utilized simulation to optimize piezoresistor design and stress distribution on the SOI diaphragm.
• Employed a 1.5 µm ultra-thin monocrystalline silicon layer in the SOI structure for improved performance.
• Fabricated the sensor using standard CMOS-compatible processes on 8-inch wafers.

Main Results:

• Achieved a high sensitivity of 2.255 mV/V/kPa and a resolution below 100 Pa at room temperature.
• Demonstrated excellent temperature stability with a TCS of -0.221 %FS/°C and TCO of -0.209 %FS/°C from 20 °C to 160 °C.
• Successfully fabricated miniaturized MEMS pressure sensors with a diaphragm size of 700 µm × 700 µm × 2.1 µm.

Conclusions:

• The developed SOI piezoresistive sensor meets the demands for high-performance low-pressure detection.
• The fabrication process is compatible with mass production, enabling volume solutions for embedded systems.
• This research provides valuable insights for future high-temperature and miniaturized low-pressure sensor development.