Multipurpose MEMS thermal sensor based on thermopiles

This paper presents design, fabrication and experimental results of multipurpose thermopile based sensor which is compatible with technological processes already developed at IHTM-IMTM for fabrication of pressure sensors. Thermal isolation is assured using back etching of bulk silicon. Thermopiles have multilayer structure and sandwich membrane consists of layer of residual n-Si and sputtered oxide. Post-etching technique was developed and functional structures with membranes below 3 mu m were fabricated. Steady state and transient behaviour of fabricated structures were anticipated by applying two-zone 1D analytical model and FEA Comsol simulation. Sensors were tested as ac-dc transfer devices, gas flow meters and vacuum detectors