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Proceedings Paper

Development of an aluminum nitride-silicon carbide material set for high-temperature sensor applications
Author(s): Benjamin A. Griffin; Scott D. Habermehl; Peggy J. Clews
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Paper Abstract

A number of important energy and defense-related applications would benefit from sensors capable of withstanding extreme temperatures (>300°C). Examples include sensors for automobile engines, gas turbines, nuclear and coal power plants, and petroleum and geothermal well drilling. Military applications, such as hypersonic flight research, would also benefit from sensors capable of 1000°C. Silicon carbide (SiC) has long been recognized as a promising material for harsh environment sensors and electronics because it has the highest mechanical strength of semiconductors with the exception of diamond and its upper temperature limit exceeds 2500°C, where it sublimates rather than melts. Yet today, many advanced SiC MEMS are limited to lower temperatures because they are made from SiC films deposited on silicon wafers. Other limitations arise from sensor transduction by measuring changes in capacitance or resistance, which require biasing or modulation schemes that can with- stand elevated temperatures. We are circumventing these issues by developing sensing structures directly on SiC wafers using SiC and piezoelectric aluminum nitride (AlN) thin films. SiC and AlN are a promising material combination due to their high thermal, electrical, and mechanical strength and closely matched coefficients of thermal expansion. AlN is also a non-ferroelectric piezoelectric material, enabling piezoelectric transduction at temperatures exceeding 1000°C. In this paper, the challenges of incorporating these two materials into a compatible MEMS fabrication process are presented. The current progress and initial measurements of the fabrication process are shown. The future direction and the need for further investigation of the material set are addressed.

Paper Details

Date Published: 5 June 2014
PDF: 9 pages
Proc. SPIE 9113, Sensors for Extreme Harsh Environments, 91130A (5 June 2014); doi: 10.1117/12.2050896
Show Author Affiliations
Benjamin A. Griffin, Sandia National Labs. (United States)
Scott D. Habermehl, Sandia National Labs. (United States)
Peggy J. Clews, Sandia National Labs. (United States)

Published in SPIE Proceedings Vol. 9113:
Sensors for Extreme Harsh Environments
Debbie G. Senesky; Sachin Dekate, Editor(s)

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