A Resonant Pressure Microsensor with a Wide Pressure Measurement Range

Area of Science:

• Microelectromechanical Systems (MEMS)
• Sensor Technology
• Materials Science

Background:

• Traditional pressure sensors face limitations in measurement range and accuracy.
• Need for robust microsensors capable of operating under extreme conditions.
• Silicon-on-Insulator (SOI) and Silicon-on-Glass (SOG) offer unique material properties for microfabrication.

Purpose of the Study:

• To develop a resonant pressure microsensor with an extended measurement range.
• To enhance the stiffness and stability of the pressure-sensing diaphragm.
• To minimize stress during fabrication and operation for improved reliability.

Main Methods:

• Fabrication utilizing photolithography, deep reactive ion etching (DRIE), chemical mechanical planarization (CMP), and anodic bonding.
• Integration of silicon islands on the SOI device layer to increase diaphragm stiffness.
• Implementation of a cylindrical vacuum cavity on the SOG cap for encapsulation.

Main Results:

• Achieved quality factors exceeding 15,000 for resonators.
• Demonstrated pressure sensitivities of 0.51 Hz/kPa and -1.75 Hz/kPa.
• Exhibited high measurement accuracy (0.017% FS) over 200-7000 kPa and -40°C to 80°C after temperature compensation.

Conclusions:

• The developed resonant pressure microsensor effectively addresses the need for wide-range, high-accuracy pressure sensing.
• The structural enhancements and vacuum encapsulation contribute to improved performance and stability.
• This technology holds promise for demanding pressure measurement applications.