FEM simulation of platinum-based microhotplate using different dielectric membranes for gas sensing applications

Purpose - The purpose of this paper is to help reduce power consumption by using platinum-based microhotplate with different dielectric membranes SiO2 and Si3N4 for gas sensing applications, and to develop platinum lift-off process using DC sputtering method for fabrication of platinum resistor. Design/methodology/approach - Semiconductor gas sensors normally require high power consumption because of their elevated operating temperature 300-600 degrees C. Considering the thermal resistant and sensitive characteristics of metal platinum as well as heat and electricity insulating characteristics of SiO2, Si3N4 and combination of both, a kind of the Si-substrate microhotplate was designed and simulated using ANSYS 10.0 tool. Thermal oxidation of Si wafer was carried out to get a 1.0 mu m thick SiO2 layer. Pt deposition on oxidized silicon substrate by lift-off was carried out using DC sputtering technique. Findings - The platinum-based microhotplate requires 31.3-70.5 mW power to create the temperature 348-752 degrees C for gas sensing applications. The SiO2 membrane can operate the gas sensitive film at higher temperature than the Si3N4 and combination of both the membranes at same power consumption. The paper also presents the FEM simulation of different heating elements like nichrome and tantalum and its comparison to platinum for microhotplate applications. Originality/value - Both the simulation and experimental work provides the low cost, high yield and repeatability in realization of microhotplate. The design and simulation work provides the better selection of heating elements and dielectric membranes. The developed experimental process provides the easy fabrication of platinum resistors using DC sputtering technique.