Study On Bulk And Thin-film Thermal Properties Based On The 3ω Method

With the advancement of science and technology, the size of the micro devices is rapidly narrowing, thus the improvement of integration density has increasingly become the main issue in scientific and technological development. Under such circumstances, the thermal management on micro devices has become a focal point. In the meantime,3ω method has long been an effective way to test the thermal conductivity of the bulk and thin film materials, thus the in-depth research on it is of great significance.Firstly, the significance and status of the related researches on the thermal conductivity of the bulk and thin film materials are introduced in this thesis, meanwhile, some measurements to test the thermal properties of the different materials are presented in details. Based on the review, we propose that the 3ω method is a relatively effective and extensively used method to test the thermal conductivity of the bulk and thin film materials. Following the discussion on the classical 3ω method that is used to measure the bulk materials and improved 3ω method that is used to measure thin film materials, we set up an experimental system, in which the Cryostat are applied to control the temperature so as to ensure an ideal environment for measurement of the samples, meanwhile, the lock-in amplifier is utilized to provide a signal and measure three harmonic voltage signal that the circuit produces.Secondly, with a view to prove the feasibility of the experimental system, this thesis measured the thermal conductivity of the bulk silicon that was calibrated in literature, and then got the curves about the thermal conductivity of the bulk silicon versus temperature; In addition, the thermal conductivity of 5μm silica,1039μm silica and 302.8nm silica were measured respectively. Among them, the 5um silica was taken as an example, and the variation curve of the thermal conductivity at temperature ranging from 30K to 340K was drawn. Eventually it can be found that the value of the thermal conductivity about silica at room temperature is 1.34W/(m · K), which is consistent with the value in literature reference. Therefore, the experimental system designed in this thesis was verified feasible.Lastly, we introduced the fundamental nature and application of fused silica which is widely used in laboratory experiments. Then we got the the thermal conductivity curves which vary with tempreture. It can be found from the curve that the value of the thermal conductivity of fused silica at room temperature is 3.0371 W/ (m · K).In summary, this thesis combined the 3ω method theory with the experiments and set up an experimental system. With such a system, we measured the thermal conductivity of the bulk silicon and thin film silica with different thickness, through which the applicability of the system is testified. Finally, we measured the thermal conductivity properties of fused silica, thus laying the foundation for the further research on the 3ω method.