Scaling of thermal CMOS gas flow microsensors: experiment and simulation

This paper reports the fabrication, characterization and numerical simulation of two sets of CMOS gas flow microsensors. The thermal sensors were produced using a commercial CMOS process followed by front or rear silicon etching to produce bridge and membrane based sensors, respectively. The dependence of the device output characteristics on design parameters and flow channel dimensions was determined experimentally, and modelled by finite element (FE) analysis. Both experiment and simulation show that the sensors probe a region of the flow profile close to the surface of the flow channel. Their output signals depend primarily on the gradient of the profile. Their sensitivity varies with the flow channel width w as w/sup -n/ with exponents n close to 1.