THERMAL-CONDUCTIVITY MEASUREMENTS ON DIAMOND FILMS BASED ON MICROMECHANICAL DEVICES

An accurate technique to measure the thermal conductivity k(T) of CVD diamond based on new micromechanical devices is presented. The thermal conductivity parallel to the surface of films with thicknesses rangin g from 2 to several hundred mu m can be determined over a wide tempera ture range. The diamond films were patterned by RIE in an oxygen plasm a to achieve accurate device dimensions. The silicon was completely re moved from a defined area leaving diamond membranes and free standing diamond cantilevers. A thin film heater generated a temperature profil e which was measured using several thermoresistors. Shape and dimensio ns of the structures were optimized using computer simulations (FEA). The effects of thermal radiation, additional metallization and insulat ion layers were minimized. Measurements on CZ silicon show a very good agreement with literature results. The thermal conductivity of diamon d films with thicknesses between 3.6 and 8 mu m grown on a silicon sub strate by the hot filament technique with different methane concentrat ions were measured between -195 and 300 degrees C. The measured values range between < 1 and 5 W cm(-1) K-1.