A Low-Power Oven-Controlled Vacuum Package Technology for High-Performance MEMS

Abstract

This paper presents a generic vacuum packaging technology for environment-resistant MEMS devices. This packaging approach simultaneously provides low-power oven-controlled thermal environment and vibration isolation using an isolation platform. The oven-controlled structure is thermally isolated from the environment by crab-leg suspensions made out of a 100 ¿m-thick glass wafer, an anti-radiation shield, and vacuum encapsulation. Performance is evaluated by packaging Pirani gauges and mode-matched tuning fork gyroscopes (M2-TFGs). The package has maintained vacuum pressure of ~6 mTorr for ~1 year. A packaged M2-TFG shows a high-Q mode-matched operation (Q~65,000) at a constant temperature of -5 °C. Allan variance analysis displays an estimated angle random walk (ARW) of 0.012 °/¿hr and a bias instability value of 0.55 °/hr at a constant -5 °C. Drive frequency stability of 0.22 ppm/°C is obtained using a compensated oven-control approach. Low power consumption of 33 mW for oven-control at 80 °C is demonstrated when the environment temperature is -30 °C.