Investigating the effect of deposition variation on the performance sensitivity of low-power gas sensors

Some stages in the microfabrication process, like deposition can introduce variations on the material characteristics and dimensional parameters of CMOS thin films. The main purpose of the current study is to assess the effect of these variations on the thermal response and calculated sensitivity of a micromachined gas sensor. The assessment is conducted for two different techniques of sensitive film deposition on the active area. The main focus is on the effect of the variations in the thermal characteristics, electrical characteristics and dimensional tolerance (induced at different levels of the microfabrication of CMOS thin films). The multilevel substructuring technique was used to reduce the computational cost of the parametric study by a factor that can reach up to 78.7% with an expense of only 3% reduction in the accuracy. This expensive computational task has shown that the variation of some material properties and geometric parameters can alter the sensitivity of gas microsensors by a factor that can reach up to ±40%. This large variation in sensor performance highlights the essential need for a close monitoring of micromachining parameters that has a greater influence on the primary variables altering the gas sensor performance.