微纳米电子器件散热过程中的物理问题

The physics of heat dissipation in micro-nano-scale devices

微纳米电子器件的散热问题是目前制约半导体工业发展的重要瓶颈。将电子器件工作时产生的热量传输到封装外壳后再耗散到环境中去需要好几个步骤,每个步骤需要不同的方法,其中有些步骤涉及到了固体中的界面热传导问题和高性能导热材料。文章先介绍了近期关于微纳米尺度器件散热问题中碰到的热传导问题在理论和实验两方面的研究进展。在热传导理论和计算方法方面,作者讨论了傅里叶定律在微纳米尺度的适用性,介绍了玻尔兹曼方程、分子动力学模拟和格林函数方法。在热传导实验方面,介绍了用扫描热显微镜测量样品表面温度和用超快激光反射法测量薄膜材料的热导率及其界面热阻。然后介绍了界面热传导问题,包括界面热阻的计算以及电子—声子相互作用对界面热阻的影响。最后作者介绍了关于高性能导热材料方面的最新进展,包括碳基导热材料、晶格结构类似于石墨烯的氮化硼材料、高分子有机材料以及界面热阻材料。

Heat dissipation in micro-nano-scale devices is one of the bottlenecks which hinder the further development of the semiconductor industry. A series of procedures should be performed to dissipate the heat generated by the electronic device to the environment, which in- volves the thermal transport across interfaces and high performance heat conducting materials. We first review the recent progress in the field of micro-nano-scale thermal transport in solids from both the theoretical and experimental approaches. In the area of thermal transport theory and computational methodology, the Boltzmann transport equation, molecular-dynamics simula- tion, and Green＇s function are discussed. For the thermal transport experiments, we present an introduction to scanning thermal microscopy which is used to measure the spatial temperature distribution of sample surfaces, as well as the ultra-fast thermoreflectance technique which is used to measure the thermal conductivity of thin films and thermal boundary resistance. Then we tackle the problem of heat transport across an interface, including the calculation of thermal boundary resistance and how this is affected by the electron-phonon interaction. Several new heat conducting materials are also discussed, including carbon-based materials, boron-nitride whose crystal structure is similar to that of graphene, polymer chains, and thermal interface materials.