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Proceedings Paper

Microfabrication and reliability study of sapphire-based Ti/Pt electrodes for thin film gas sensor applications
Author(s): Wenmin Qu; Wojtek Wlodarski; Michael W. Austin
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Paper Abstract

The paper describes design, fabrication and characterization of a Ti/Pt electrode system, on a sapphire substrate. It serves as substrates for subsequent deposition of gas sensitive films. The fabrication has been accomplished on both sides of a sapphire wafer. Wet chemical etching and the lift-off method have respectively been used for structuring the electrode and the heater patterns. The mechanical stability and the electrical conductivity of the resultant Ti/Pt films are greatly affected by the subsequent heat treatment procedures. The diffusion of titanium ions into platinum has been examined using SIMS depth profiles. After annealing at 600 degrees C for 5 hours, the temperature coefficient of the Ti/Pt film stabilized on the value 0.0033 K-1, which approaches the pure platinum bulk value of 0.0039 K-1. With a good mechanical and thermodynamical stability at high temperatures and under oxidizing and reducing conditions, the sapphire based Ti/Pt electrode system is well suited for gas sensor fabrication. As an example of its application, we report a highly sensitive O3 gas sensor developed by evaporating a WO3 thin-film onto this electrode.

Paper Details

Date Published: 1 October 1999
PDF: 9 pages
Proc. SPIE 3892, Device and Process Technologies for MEMS and Microelectronics, (1 October 1999); doi: 10.1117/12.364486
Show Author Affiliations
Wenmin Qu, Royal Melbourne Institute of Technology (Australia)
Wojtek Wlodarski, Royal Melbourne Institute of Technology (Australia)
Michael W. Austin, Royal Melbourne Institute of Technology (Australia)

Published in SPIE Proceedings Vol. 3892:
Device and Process Technologies for MEMS and Microelectronics
Kevin H. Chau; Sima Dimitrijev, Editor(s)

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