1.156-GHz self-aligned vibrating micromechanical disk resonator.

Area of Science:

• Microelectromechanical Systems (MEMS)
• Materials Science
• Electrical Engineering

Background:

• Traditional fabrication methods for micromechanical resonators face challenges in achieving precise alignment, impacting performance.
• Achieving high-frequency operation (GHz range) with high quality factors (Q) is crucial for advanced sensing and communication applications.

Purpose of the Study:

• To introduce a novel fabrication methodology enabling self-alignment of micromechanical structures.
• To demonstrate the performance of polysilicon micromechanical disk resonators fabricated using this new technique, focusing on resonance frequency and Q factor.

Main Methods:

• Utilized a new fabrication process allowing self-alignment of the resonator's stem to the disk's center.
• Fabricated polysilicon micromechanical disk resonators operating in a radial-contour mode.
• Characterized resonator performance, including resonance frequency and Q factor, in both vacuum and air environments.

Main Results:

• Achieved resonance frequencies up to 1.156 GHz with Q factors >2,650 at this frequency in both vacuum and air.
• Demonstrated a 734.6-MHz resonator with Q factors of 7,890 (vacuum) and 5,160 (air).
• The self-alignment technique significantly improved resonator balancing, enabling high Q at gigahertz frequencies for the first time.

Conclusions:

• The novel self-alignment fabrication method is effective for producing high-performance micromechanical disk resonators.
• These resonators demonstrate potential for applications requiring high-frequency operation and high Q factors.
• An equivalent electrical circuit model was developed to accurately predict the performance of these disk resonators.