Temperature-Insensitive Structure Design of Micromachined Resonant Accelerometers

Area of Science:

• MEMS technology
• Sensor design
• Materials science

Background:

• Micromachined resonant accelerometers (MRAs) fabricated using silicon on glass technology are susceptible to temperature drift errors.
• Inherent thermal stress during fabrication processes, such as die attach, significantly impacts MRA performance.
• Existing MRA designs often struggle to mitigate these thermal stress-induced errors effectively.

Purpose of the Study:

• To propose and validate novel structural designs for MRAs that effectively attenuate thermal stress.
• To reduce temperature drift errors in silicon on glass micromachined resonant accelerometers.
• To enhance the bias stability and overall performance of MRAs under varying thermal conditions.

Main Methods:

• Design optimization of bonding anchor locations and substrate shape to isolate thermal stress.
• Implementation of an isolation frame with a single anchor to replace dispersed anchors in suspension systems.
• Finite element analysis (FEA) for simulation and experimental validation of the proposed MRA structures.
• Characterization of differential temperature sensitivity and bias stability of MRA prototypes.

Main Results:

• Both proposed MRA structures demonstrate a significant reduction in thermal stress effects.
• Experimental results show a differential temperature sensitivity as low as 1.9 μg/°C.
• The 15-day bias stability of a prototype MRA reached an impressive 1.4 μg.
• The novel designs effectively isolate the accelerometer from thermally induced stresses.

Conclusions:

• The proposed structural designs offer a viable solution for mitigating thermal stress in silicon on glass MRAs.
• Optimized MRA designs lead to substantially improved temperature drift performance and bias stability.
• These advancements are crucial for high-precision inertial sensing applications requiring stable performance across temperature variations.