A new structure for measuring the thermal conductivity of thin film

A new microdevice for measuring the thermal conductivity of thin film is presented. It is based on the static-state method, which is widely used and a simple technique for measuring the lateral thermal conductivity of thin film. The device is fabricated using micromachining process, which is 800×2000μm bridge membrane with 30×100μm beams. The heater and thermometer across the bridge membrane through the beams are used to create heat flux and to measure the temperature. On the membrane, heat flux is very uniform and the temperature is evenly distributed, which has been verified by simulation, making the system error smaller than conventional rectangular structure. Silicon nitride thin films with thickness from 0.5μm to 2μm have been investigated using the technique. The measurement result supports the size effect of the thermal conductivity for thin film.