Model and observations of dielectric charge in thermally oxidized silicon resonators

Gaurav Bahl, Renata Melamud, Bongsang Kim, Saurabh A. Chandorkar, James C. Salvia, Matthew A. Hopcroft, David Elata, Robert G. Hennessy, Rob N. Candler, Roger T. Howe, Thomas W. Kenny

Research output: Contribution to journalArticlepeer-review

Abstract

This paper investigates the effects of dielectric charge on resonant frequency in thermally oxidized silicon resonators hermetically encapsulated using epi-seal. SiO2 coatings are effective for passive temperature compensation of resonators but make the devices more susceptible to charging-related issues. We present a theoretical model for the electromechanical effects of charge trapped in the dielectrics within the transduction gap of a resonator. Observations of resonance frequency against varying resonator bias voltage are fitted to this model in order to obtain estimates for the magnitude of the trapped oxide charge. Statistics collected from wet-and dry-oxidized devices show that lower fixed oxide charge can be expected upon dry oxidation. In addition, observations of time-varying resonator frequency indicate the presence of mobile oxide charge in a series of voltage biasing and temperature experiments.

Original languageEnglish (US)
Article number5345822
Pages (from-to)162-174
Number of pages13
JournalJournal of Microelectromechanical Systems
Volume19
Issue number1
DOIs
StatePublished - Feb 2010
Externally publishedYes

Keywords

  • Charging
  • Dielectrics
  • Frequency drift
  • Reliability
  • Resonators
  • Silicon dioxide

ASJC Scopus subject areas

  • Mechanical Engineering
  • Electrical and Electronic Engineering

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