Research on Packaging Reliability and Quality Factor Degradation Model for Wafer-Level Vacuum Sealing MEMS Gyroscopes

Area of Science:

• Engineering
• Materials Science
• Physics

Background:

• Micro-Electro-Mechanical Systems (MEMS) gyroscopes are crucial in various high-tech applications.
• Ensuring the long-term performance and survivability of MEMS gyroscopes necessitates reliable packaging.
• Existing gas leakage models for wafer-level MEMS gyroscope packaging are scarce, hindering reliability assessments.

Purpose of the Study:

• To develop a novel gas leakage model for wafer-level MEMS gyroscopes.
• To evaluate the packaging reliability of these sensors under gas leakage conditions.
• To understand the impact of gas leakage on gyroscope performance metrics.

Main Methods:

• Derivation of theoretical relationships based on thermodynamics and hydromechanics.
• Analysis of the connection between the quality factor, gas molecule count, and a degradation model.
• Experimental validation of the derived gas leakage model at the wafer-level packaging stage.

Main Results:

• The reciprocal of the quality factor shows an exponential relationship with gas leakage time.
• Theoretical predictions align with experimental findings, with coefficients of determination (R²) exceeding 0.95.
• Predicted stable quality factor values are 6609.4 (drive mode) and 1205.1 (sense mode).
• The average degradation characteristic time is determined to be 435.84 hours.

Conclusions:

• The proposed gas leakage model accurately reflects the degradation of MEMS gyroscope quality factor over time.
• Packaging integrity is maintained for at least 3486.72 hours (eight times the characteristic time) before stability is reached.
• This research provides a critical tool for assessing and ensuring the reliability of wafer-level MEMS gyroscope packaging.