PURPOSE: To make it possible to carry out easily cutting of a sapphire wafer without spoiling the surface physical properties of a gas snsor element, by cutting the sapphire wafer of a specific thickness on the surface of which many gas sensor elements are formed by means of scribing.
CONSTITUTION: A pair of electrodes consisting of electrodes 6 and 8 is e.g. thin membranes comprised of platinum, which is formed on each divided area of a sapphire wafter 2 by means of sputtering process. Dimensions of the electrodes 6 and 8 are 1.6×0.6mm and these electrodes are formed face to face each other in the distance of 0.4mm. The membrane thickness is e.g. 0.3μm. As the materials constituting the electrodes, not only platinum, but also those having high electric conductivity such as gold, silver, aluminum can be used. On the sapphire wafer 2, one of the surface on which many gas sensor elements 4 are formed, scratched cuts 12 are drawn in parallel to each other lengthwise and crosswise by means of a well known scriber, a diamond needle. Moreover, crosswise scratched cuts 12 are drawn perpendicular thereto.
MATSUMOTO TAKESHI
MATSUZAKA TAKASHI
TOSHIBA CORP