High sensitivity acoustic transducers with thin p+ membranes and gold back-plate

A. E. Kabir, Rashid Bashir, J. Bernstein, J. De Santis, R. Mathews, J. O. O'Boyle, C. Bracken

Research output: Contribution to journalArticlepeer-review

Abstract

High sensitivity acoustic transducers (microphones) have been fabricated on 5″ wafers in a production environment and the experimental results are presented. One of the main advantage of this microphone design is that it can be fabricated on a single wafer eliminating the need for the multiple wafers and subsequent wafers bonding steps as in conventional designs. The devices use thin (approximately 3 μm) p+silicon membranes as the active movable element and a thick perforated plated gold back plate. The p+membranes are fabricated using an optimized boron solid source diffusion at 1150 °C. Ethylene-Diamine-Pyro-Catecol (EDP) etching at 100 °C was performed from the backside of double-sided polished wafers to release the thin silicon membranes. The zero-bias capacitance with the air gap was 2.2 pF and it increased to 2.4 pF at 9 V. The frequency response was measured and the measured sensitivity of 5.28 mV/Pa at 5 V and 10.77 mV/Pa at 9 V at 1 kHz are among the highest reported in literature for micro-machined acoustic transducers.

Original languageEnglish (US)
Pages (from-to)138-142
Number of pages5
JournalSensors and Actuators, A: Physical
Volume78
Issue number2
DOIs
StatePublished - Dec 14 1999
Externally publishedYes

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Instrumentation
  • Condensed Matter Physics
  • Surfaces, Coatings and Films
  • Metals and Alloys
  • Electrical and Electronic Engineering

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