Micro-hotplate for integrated thin-film gas sensors

The paper reports a novel approach to fabricate micro-hotplate for thin film gas sensor. The approach uses frontside anisotropic etching of silicon together with special layout to create the thermally isolated structure. Sandwich of inter-dielectric layers and aluminum interconnection provides the supporting material while highly doped boron diffusion provides the heating and temperature sensing. The design incorporates guard heater layout that improves the temperature uniformity. Simulation result shows that the temperature variation on a sensor film of 50 × 60 μm2 is less than 20°C when the operating temperature is 350°C. The micro-hotplate fabricated exhibits heating efficiency of about 7°C/mW and CMOS compatibility.