SELECTED-AREA DEPOSITION OF MULTIPLE ACTIVE FILMS FOR CONDUCTOMETRIC MICROSENSOR ARRAYS

A new generation of planar conductometric gas sensors is being develop ed which combines active semiconducting oxide films with Si-micromachi ned 'micro-hotplate' array structures. These devices are tailored for a variety of applications by tuning both the composition of multiple t ypes of active films and the temperature cycles programmed for individ ual elements within an array. In this paper we describe and demonstrat e the approach, and present results for, a chemical vapor deposition ( CVD)-based self-lithographic microfabrication method. This method is b eing examined as a highly efficient and compatible means of depositing oxide films and low-coverage catalytic metal overlayers on the micros ensor elements of micro-hotplate arrays. Real-time monitoring of the f ilm growth processes is provided by conductance measurements, and surv eys of processing/property relationships can be performed in a very ef fective manner to determine optimal fabrication methods for multiple-a ctive material arrays.