Wafer-scale packaging for FBAR-based oscillators

Recent advances in temperature-compensation for FBAR (Film Bulk Acoustic Resonators) have brought this technology forward as a serious contender in the oscillator marketplace. As with any mechanical resonator oscillator, a cost-effective hermetic package combined with circuit technology are critical for commercial application. Billions of FBAR duplexers have been fabricated using Avago Technologies´ wafer-scale packaging process, whereby a silicon lid wafer is Au-diffusion-bonded to a base FBAR wafer to make a robust, hermetic package. This paper presents a method for integrating circuitry into the lid wafer to form a sub-0.1 mm³, sub mW, 1.5 GHz temperature-compensated chip-scale oscillator. Circuit integration, testing and performance will be discussed.