WO3-based thin film micro-gas sensor was fabricated and the NOx gas sensing
as well as electrical properties have been investigated. To obtain the opt
imal heat distribution, the structure of micro-hot plate was designed from
the result of finite element simulation and was prepared by backside etchin
g with KOH solution.
The micro-hot plate was made out of N/O/N diaphragm with the thickness of 0
.6 nm and area of 1.5 x 1.5 mm(2). The power consumption to maintain the de
vice temperature of 300 degrees C was about 60 mW. WO3, thin film was therm
ally evaporated on micro-diaphragm. The film exhibited a fast response to N
Ox gas and the relationship between sensitivity and NO2 concentration showe
d good linearity in the gas concentration range of 0-30 ppm NO2. The sensit
ivity of micro-gas sensor to NOx was correlated with the microstructure of
the thin film. (C) 2000 Elsevier Science S.A. All rights reserved.