A Wafer-Level Fabricated Heating-Vacuum Micro-Platform with Resonant MEMS Monolithically Integrated

Area of Science:

• Micro-electro-mechanical Systems (MEMS)
• Semiconductor Packaging
• Thermal Management

Background:

• Resonant MEMS devices require stable operating conditions for optimal performance.
• Environmental factors like temperature fluctuations degrade MEMS device accuracy and reliability.
• Existing packaging solutions often lack integrated thermal control, limiting performance in variable temperature environments.

Purpose of the Study:

• To develop a silicon-based wafer-level vacuum packaging platform with a monolithically integrated micro-oven.
• To provide stable vacuum and constant temperature conditions for resonant MEMS devices.
• To significantly improve the performance and reduce temperature sensitivity of MEMS resonators.

Main Methods:

• A three-layer wafer-level vacuum packaging process was employed.
• The platform integrates a silicon thermistor, thermal isolation structure, and heater.
• A mask and an additional silicon wafer were utilized for the packaging process.

Main Results:

• Achieved a vacuum level of approximately 6 mTorr.
• Reduced the temperature coefficient of the resonant frequency for MEMS resonators by 48 times.
• Reduced the temperature coefficient of the quality factor by 19 times within a -40 °C to 80 °C range.
• The micro-oven heater consumed approximately 364 mW at -40 °C ambient temperature to maintain 100 °C.

Conclusions:

• The developed wafer-level vacuum packaging platform with an integrated micro-oven effectively stabilizes MEMS resonators.
• This integrated approach significantly enhances MEMS device performance by mitigating temperature-induced variations.
• The method offers a cost-effective, batch-producible solution for high-performance MEMS packaging.