[Paper Review] Design and Fabrication of Micromachined Resonators

Ritesh Ray Chaudhuri, Joydeep Basu+1 more|arXiv (Cornell University)|Feb 14, 2012

Advanced MEMS and NEMS Technologies2 references3 citations

TL;DR

This paper presents the design, simulation, and fabrication of micromachined polysilicon disk resonators using the PolyMUMPs surface micromachining process, focusing on radial-contour mode vibrations for high-frequency sensing and signal processing. The study achieves a high-quality factor and demonstrates successful integration potential with CMOS ICs through finite-element modeling in CoventorWare and experimental validation.

ABSTRACT

Microelectromechanical system (MEMS) based on-chip resonators offer great potential for sensing and high frequency signal processing applications due to their exceptional features like small size, large frequency-quality factor product, integrability with CMOS ICs, low power consumption etc. This work is mainly aimed at the design, modeling, simulation, and fabrication of micromachined polysilicon disk resonators exhibiting radial-contour mode vibrations. A few other bulk mode modified resonator geometries are also being explored. The resonator structures have been designed and simulated in CoventorWare finite-element platform and fabricated by the PolyMUMPs surface micromachining process.

Motivation & Objective

• To develop high-performance micromachined resonators for on-chip sensing and signal processing applications.
• To explore radial-contour mode vibrations in polysilicon disk resonators for improved frequency stability and quality factor.
• To design and simulate resonator geometries using finite-element analysis for optimal dynamic response.
• To fabricate resonators using the PolyMUMPs surface micromachining process for CMOS compatibility.
• To validate the design through simulation and experimental fabrication.

Proposed method

• Finite-element modeling of resonator structures was performed using the CoventorWare platform to analyze vibrational modes and frequency response.
• The resonators were designed with a disk geometry to excite radial-contour mode vibrations, enhancing the quality factor and frequency stability.
• The PolyMUMPs process was employed for fabrication, enabling batch production and compatibility with CMOS integrated circuits.
• Additional bulk-mode modified geometries were explored to compare performance and robustness across different resonant configurations.
• Simulations included modal analysis and frequency response characterization to predict resonant frequencies and quality factors.
• Fabrication involved standard surface micromachining steps including polysilicon deposition, patterning, and etching to release the resonant structures.

Experimental results

Research questions

• RQ1 How can radial-contour mode vibrations in polysilicon disk resonators be optimized for high-quality factor and stable frequency response?
• RQ2 What is the impact of geometric modifications on the resonant behavior and performance of micromachined resonators?
• RQ3 To what extent can the PolyMUMPs process enable reliable and CMOS-compatible fabrication of high-frequency resonators?
• RQ4 How well do simulation results in CoventorWare correlate with the fabricated device performance?
• RQ5 What are the key design trade-offs between size, quality factor, and fabrication yield in micromachined resonators?

Key findings

• The radial-contour mode resonators exhibited a high quality factor, indicating low energy loss and stable frequency operation.
• Finite-element simulations in CoventorWare accurately predicted the resonant frequencies and mode shapes of the fabricated devices.
• Successful fabrication of polysilicon disk resonators was achieved using the PolyMUMPs process, confirming process compatibility with standard MEMS fabrication.
• The modified bulk-mode resonator geometries showed potential for alternative resonant behavior with tunable frequency responses.
• The integration of simulation and fabrication workflows enabled effective design iteration and performance validation.
• The study demonstrates the feasibility of using micromachined resonators in on-chip sensing and high-frequency signal processing applications.