Design and implementation of a micromechanical silicon resonant accelerometer

Area of Science:

• Microsystems Engineering
• Materials Science
• Sensor Technology

Background:

• Micromechanical silicon resonant accelerometers offer high precision, sensitivity, and stability.
• Temperature variations significantly impact performance due to thermal stress from mismatched material expansion (silicon and glass).
• Existing Silicon on Glass (SOG) techniques are susceptible to thermal drift, affecting frequency output.

Purpose of the Study:

• To design a novel micromechanical silicon resonant accelerometer structure.
• To mitigate the adverse effects of temperature fluctuations on accelerometer performance.
• To improve the thermal stability and accuracy of MEMS accelerometers.

Main Methods:

• A specialized accelerometer structure was designed based on the working principles of micromechanical resonant accelerometers.
• A closed-loop drive circuit utilizing a phase-locked loop was developed.
• Fabrication and testing of a prototype were conducted to evaluate performance.

Main Results:

• The designed accelerometer structure effectively reduces thermal stress during fabrication and packaging.
• The prototype exhibited unloaded resonant frequencies around 31.4 kHz and 31.5 kHz.
• Key performance metrics include a scale factor of 66.24003 Hz/g, scale factor stability of 14.886 ppm, bias stability of 23 μg, and a bias temperature coefficient of 0.0734 Hz/°C.

Conclusions:

• The novel accelerometer design significantly reduces temperature-induced errors in micromechanical silicon resonant accelerometers.
• The developed structure demonstrates excellent stability and repeatability, making it suitable for high-precision applications.
• This advancement contributes to the development of more robust and reliable MEMS accelerometers for demanding environments.