A NEW METHOD TO MEASURE THERMAL CONDUCTIVITY OFTHIN ELECTRICALLY INSULATING FILMS DEPOSITED ONSILICON SUBSTRATES BY A THERMO-REFLECTANCETECHNIQUE

摘要

This paper describes development of an advanced method, which can provide more accurate values of thermalrnconductivity of very-thin insulating films on a substrate with much simple preparation of the specimen inrncomparison with the three-omega method. In this method the metal film layer, which is deposited on the thinrninsulating films, is Joule heated periodically and the ac-temperature response of the metal film surface isrnmeasured by a thermo-reflectance technique. So one-dimensional thermal conductivity measurement system canrnbe applied to the three-layered system. The one-dimensional thermal conduction equation of the system has beenrnsolved analytically. In an appropriate frequency range it results in a simple equation. In this method calibrationrnfactors of the thermo-reflectance coefficient can be determined using known thermal effusivity of the substrate.rnThe present method was applied to thermally oxidized SiO2 films (1000 to 20 nm thick) on silicon substrates.rnThe present results of the thermal conductivity coincide with that of VAMAS TWA23 within ±10 %.