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A Fractal Model for Effective Thermal Conductivity of Isotropic Porous Silica Low-k Materials 总被引:1,自引:0,他引:1 下载免费PDF全文
We establish a new model based on fractal theory and cubic spline interpolation to study the effective thermal conductivity of isotropic porous silica low-k materials. A 3D fractal model is introduced to describe the structure of the silica xerogel and silica hybrid materials (such as methylsilsesquioxane, MSQ). Combined with fractal structure, a more suitable medium approximation is developed to study the isotropic porous silica xerogel and MSQ materials. Cubic spline interpolation for fitting discrete predictions from the fractal model is used to obtain the continuous function of the effective thermal conductivity versus porosity. Compared with other common models, the effective thermal conductivity predicted by our model presents better agreement with the experimental data for all porosity. These results indicate that the proposed model is valid. 相似文献
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Depth profiled positronium (Ps) annihilation lifetime spectroscopy (PALS) is an extremely useful probe of the pore characteristics in nanoporous low-dielectric (low-k) constant thin films. PALS has also been considered as a potential probe to investigate diffusion barrier integrity and the structural changes of porous low-k films during their integration with Cu. Hence, it is essential to understand the diffusion behaviour of positronium/Cu atoms in the films. In this work, based on the fact that porous materials possess characteristics of statistical self-similarity, a fractal model, the Menger sponge model, has been applied to simulate the structure of a promising dielectric, porous methylsilsesquioxane (MSQ) films. The diffusion behaviour of Ps out of the fractal model and into the surrounding vacuum is studied by means of the diffusion equation and traditional advective-diffusive theory. Predictive results from our model show good agreement with measurement data. 相似文献
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