Development of a Frequency-Domain Method Using Completely Optical Techniques for Measuring the Interfacial Thermal Resistance between the Metal Film and the Substrate

Abstract

In this paper, we describe the development of a new frequency-domain (FD) method using completely optical techniques for determining the interfacial thermal resistance between a metal film and its substrate. The 3ω method, which is a FD method based on the technique of photolithography to define a metal-film heater/thermometer pattern, has been most widely used so far. The 2ω method implemented a thermoreflectance technique for measuring ac temperature. In this study we additionally implement a laser technique for periodic heating. Our new method can provide the absolute value of interfacial thermal resistance between a film and its substrate, using the known thermophysical properties of the substrate material, even though the optical power of the pump laser and the optical properties of the metal film are unknown. To verify the method, we measure the thermal resistance of interfaces such as, Au–Al2O3, Bi–Al2O3, Au–SiO2 (thermally oxidized), and Bi–SiO2 (thermally oxidized). The results of the measurements show good agreement with the data obtained by the 2ω method and with the data theoretically predicted using the diffusion mismatch model (DMM).