A Temperature-Insensitive Resonant Pressure Micro Sensor Based on Silicon-on-Glass Vacuum Packaging

Area of Science:

• Microelectromechanical systems (MEMS)
• Sensor technology
• Materials science

Background:

• Accurate pressure sensing is critical in various scientific and industrial applications.
• Existing resonant pressure sensors often suffer from temperature-induced errors, limiting their performance.
• Developing temperature-insensitive pressure sensors is crucial for reliable measurements across diverse environments.

Purpose of the Study:

• To present a novel temperature-insensitive resonant pressure sensor.
• To investigate the use of silicon-on-insulator (SOI) and silicon-on-glass (SOG) materials for enhanced sensor performance.
• To achieve high sensitivity and low nonlinearity in pressure measurements.

Main Methods:

• Fabrication of a resonant pressure sensor using SOI wafer and SOG cap for vacuum packaging.
• Utilizing the bending of a pressure-sensitive diaphragm to modulate resonator frequencies.
• Employing finite element analysis (FEA) for numerical simulations to optimize sensor design and analyze thermal stress.
• Experimental characterization of sensor performance, including Q-factor, pressure sensitivity, nonlinearity, and temperature sensitivity.

Main Results:

• Achieved high Q-factors (>16,000) for the resonators.
• Demonstrated a differential pressure sensitivity of 11.89 Hz/kPa with low nonlinearity (0.01% F.S).
• Obtained a significantly low temperature sensitivity of ~1 Hz/°C across a wide temperature range (-45 °C to 65 °C), outperforming existing sensors.

Conclusions:

• The developed resonant pressure sensor exhibits excellent performance characteristics, including high sensitivity and low nonlinearity.
• The innovative use of SOG cap effectively mitigates thermal stress, leading to remarkable temperature insensitivity.
• This sensor technology holds significant potential for high-precision pressure monitoring in demanding environments.