Study On Thin-films Thermal Conductivity Measurement System Based On The3ω Method

The3co method is effective for the thermal physical properties measurement and it is widely used in thermal conductivity measurement of thin-films. With the rapid development of micro electronic technology, study on the thermal properties of thin films is very important for optimizing the thermal design and thermal management. Existed commercial instruments for thermal property measurement have not been used to test film material thermal physical properties for the time being. So the experimental technology and method are the interesting topics of the research area of microscale thermal characteristics.A set of3ω method test system was built which was applied to thermal conductivity measurement of thin-films. The system consisted of a lock-in amplifier which acts as the driving instrument and test instrument, a sourcemeter and a vacuum system with controllable temperature. Firstly, thermal conductivity of thermal oxidation SiO2films with a thickness of1.3μm were measured in the temperature of300K using the3ω me thod, the value is1.4W/mK and the effectiveness of the system was verified. Secondly, according to the measurement system, the thermal conductivities of SiO2thin films were obtained in the temperature range of100-310K.The results show that the thermal conductivity increases with the increasing of temperature. It has a good agreement with those from literatures.At present, it is common to use transient thermo-reflectance method based on a pulse laser or a suspended microstructure to measure thermal conductivity of metal thin films. Compared with the3ω method, these methods have the disadvantage of requiring a complicated experiment system or processes. In this paper, according to a two-dimensional heat transfer model in the low-frequency regime, the in-plane thermal conductivity of platinum and gold thin films were obtained based on the3co method. The good agreement between our results and those from literature demonstrated the feasibility of the3co method to measure thermal conductivity of metal films.Gas thermal conductivities are usually obtained using the transient-hot wire method. However, it has the disadvantage of requiring one long wire, so the natural convection during the tests has effect on the results. Furthermore, a rather complex fitting procedure must be performed on the experimental data in order to interpret the tested thermal properties. The advantage of the3ω method is that the thermal conductivity can be directly accessed by measuring the slop of the experimental curve without any complicated data post-processing or fitting procedures. Compared with the transient-hot wire method, the3ω method uses a shorter hot wire and reduces the effect of the natural convection.To sum up, the3ω method test system was firstly set up. Then the thermal conductivity of silicon, glass, gas, thermal oxidation SiO2films, platinum and gold thin films are respectively measured b ase on the3ω method. The study will help to improve thermal management and design of microelectronic devices. At the same time, the good agreement between our results and those from literatures demonstrated the feasibility of the3co method to measure thermal conductivity of metal films as well as gases. Compared with other testing method, our method simplifies the test system and reduces the test cost.