A phase-sensitive technique for the thermal characterization of dielectricthin films

A phase-sensitive measurement technique for determining two independent the rmal properties of a thin dielectric film is presented. The technique invol ves measuring a specimen's front surface temperature response to a periodic heating signal over a range of frequencies. The phase shift of the tempera ture response is fit to an analytical model using thermal diffusivity and e ffusivity as fitting parameters, from which the thermal conductivity and sp ecific heat can be calculated. The method has been applied to 1.72-mu m thi ck films of sie, thermally grown oil a silicon substrate. Thermal propertie s were obtained through a temperature range from 25 degrees C to 300 degree s C. One interesting outcome stemming from analysis of the experimental dat a is the ability to extract both thermal conductivity and specific heat of a thin film from phase information alone, The properties obtained with this method are slightly below the bulk values for fused silica with a measured room temperature (25 degrees C) thermal conductivity of 1.28 +/- 0.12 W/m- K.