A thin-film gas detector for semiconductor process gases

The authors report an integrated silicon sensor capable of monitoring the purity of semiconductor process gases at or near the point of use. The device utilizes a selectively etched dielectric window, which supports a thin deposited metal film and electrodes for sensing the film conductivity. The planar 1.2-mm*1.2-mm*1- mu m-thick window has a buried diffused-silicon heater. The window has a heating efficiency of about 3 degrees C/mW and a time constant of 10 ms. With an 8.5-nm-thick Pt film, the device has shown sensitivity to O/sub 2/ to CF/sub 4/ but not to CF/sub 4/ alone.<>