Very High Q-Factor, Fully CMOS Compatible, Inexpensive MEMS Resonator

Applications

  • Bulk acoustic wave (BAW) filter
  • MEMS resonators for:
    • wireless communication
    • telecommunication
    • microprocessor technology
    • clocking and transceiver circuitry

Problem Addressed

An unreleased MEMS resonator integrated with CMOS forms a single chip solution that offers clocks, filters, and sensors with superior performance at GHz-frequencies, while reducing size, weight, and power consumption of the overall system. Direct CMOS integration simplifies the fabrication process as no post-processing or special packaging is required. Until now, such MEMS resonators have demonstrated moderate low quality factor (Q~20).

Technology

This technology improves the Q-factor of an unreleased MEMS by increasing the aspect ratio of the resonator structure. The aspect ratio is increased by using an array of deep trench capacitors that serve both as electrical capacitors for electromechanical transduction and as mechanical structures for Acoustic Bragg reflectors. The architecture reduces the footprint and alleviates fabrication complexity. The performance of the MEMS structure is further enhanced by using two interleaved trench-filling materials to achieve much higher Q (>1000).

Advantages

  • Fully CMOS compatible, requires no packaging or post-processing
  • Very high quality (Q) factor 
  • Small footprint
  • Low power consumption
  • High yield, low cost