Measurement of the Thermal Conductivity of Dielectric Thin Solid Films with a Thermal Comparator

摘要

Low thermal conductivity has important implications for electric and optical applications, where heat deposited in a thin layer must be dissipated to prevent damage. Models which account for thermal transport in thin film structures may have no predictive value if they employ bulk conductivity data. Most techniques utilized to measure the thermal conductivity of thin solid films are difficult and time consuming. The method we have developed is relatively rapid, nondestructive, and is capable of evaluating the samples in a conventional film on substrate geometry. Our thermal conductivity apparatus consists of a control and readout module, signal processing equipment, and an environmentally isolated sample chamber enclosing a sample stage. The commercial unit was converted into a high precision device by temperature controlling both the samples and the sample stage, and by performing averaging of the output signal. The thermal conductivity values obtained are below those of bulk solids. In addition, the conductivities seem to increase with increasing film thickness. Titania seems to have a higher thermal conductivity when deposited by ion-beam sputtering rather than electron-beam evaporation. Some of the electron-beam films were crazed, indicating high levels of stress. The effect of stress and crazing on thermal conductivity is not readily apparent. 11 refs., 1 fig., 1 tab. (ERA citation 13:036871)