An online test microstructure for thermal conductivity of surface-micromachined polysilicon thin films

An online test structure for measuring the thermal conductivity of surface micromachined polysilicon thin films is presented. In the structure, a pair of microstructures, i.e., a reference structure and a test structure, are used. The surface micromachined structures are heated electrically. Heat dissipation by convection, radiation, and heat transfer through the air gap and into the substrate is considered in an electrothermal model. The model is confirmed by ANSYS Software. In experiments, current-voltage measurements are only required, and all measurements can be carried out in free air. The surface-micromachined and p-doped polysilicon thin films with a sheet resistance 116.25 Ω/sq. are measured to have a thermal conductivity 28.7 W/mK at 300 K.