Integration of P-Cuo thin sputtered layers onto microsensor platforms for gas sensing

Abstract

P-type semiconducting copper oxide (CuO) thin films deposited by radio-frequency (RF) sputtering were integrated onto microsensors using classical photolithography technologies. The integration of the 50-nm-thick layer could be successfully carried out using the lift-off process. The microsensors were tested with variable thermal sequences under carbon monoxide (CO), ammonia (NH3), acetaldehyde (C2H4O), and nitrogen dioxide (NO2) which are among the main pollutant gases measured by metal-oxide (MOS) gas sensors for air quality control systems in automotive cabins. Because the microheaters were designed on a membrane, it was then possible to generate very rapid temperature variations (from room temperature to 550 °C in only 50 ms) and a rapid temperature cycling mode could be applied. This measurement mode allowed a significant improvement of the sensor response under 2 and 5 ppm of acetaldehyde.