Thermo-molecular study of high temperature superconductor integrated circuit(IC)

高温超导体在诸如约瑟夫森结等电子集成电路器件中具有很大的应用前景。这些超导器件的性能受温度场的影响很大，温度场的预测需要在原子或分子水平的微尺度上的热传导知识，即分子工程研究。本文从热分子理论的角度研究了超导材料的热传导及相关的热特性，以及高温超导材料集成电路中热场与电磁场的相互作用，以明确高温超导材料高密度集成电路的热问题.高温超导材料的热传导和热性质：通过求解超导材料中原子振动和对/非对电子运动的分子动力学和Boltzmann方程 ...更多信息 结果表明，热能的传递具有金属导热和半导体导热的两个方向性特征，分别受电子运动和原子振动的控制。在低于临界温度的温度下，热主要通过原子振动传导。当材料颗粒或薄膜的尺寸为原子振动相关长度的数量级时，温度在这些边界处表现出与辐射传热相同的大的跳跃。这些尺寸效应在较低的温度下更容易发生，即使是大规模的电路。高温超导元件的热相互作用：为了在混合系统中制造超导和/或半导体材料的高密度集成电路，其具有很强的热传导方向性，需要详细了解电路元件之间的热相互作用。在膜单元边界处，原子振动和电子运动将被分散、反射和透射，边界对膜厚方向和沿着膜的热传导影响很大。对于超导材料，这些特征分别在低于和高于临界温度的温度下由原子振动和电子运动的边界效应控制。这些效应占主导地位的晶粒尺寸或膜厚度为100 nm的量级，分别与金属类和半导体类热传导的温度的三次和四次幂成反比地增加。这些特性决定了集成电路在尺寸和密度上的热极限.电路元件之间的热和电磁相互作用：临界电流决定了超导的稳定性，是温度和相关磁场的函数。临界电流由垂直于电流的截面中的局部临界电流密度的面积积分确定。同时考虑定向热传导的热特性和边界效应，可以对温度场进行预测。对于一个简单的集成系统，计算结果表明，尺寸效应和结构效应控制着集成系统的热极限。少

High temperature superconductors possess great promise for application in electronic integrated circuit devices such as Josephson junctions. The performance of these superconducting devices is greatly affected by the temperature field of which prediction requires the knowledge of heat conduction in microscale of atomic or molecular levels, that is, molecular engineering studies. In the present study, the heat conduction and the related thermal characteristics of superconducting materials are studied from the standpoint of thermo-molecular theory as well as the interaction between thermal and electromagnetic fields in the integrated circuits of high-temperature superconducting materials to make clear the thermal problems of high-density integration of these devices.1. Heat conduction and thermal properties of high-temperature superconducting materials : By solving the molecular dynamics and Boltzmann equations of atomic vibration and pair/nonpair electron motion in superconducting mater … More ials, it is shown that the transfer of thermal energy has two directional features of metallic and semiconductor heat conductions which are controlled by electron motion and atomic vibration, respectively. At temperatures lower than the critical temperature, heat is conducted mainly through the atomic vibration. When the size of material grains or thin films is of the order of the correlation length of atomic vibration, the temperature shows great jumps at these boundaries as in the radiation heat transfer. These size effects occur more easily at lower temperatures even for large scale circuits.2. Thermal interactions of high-temperature superconducting elements : In order to make high-density integrated circuits of superconducting and/or semiconducting materials in hybrid systems, which have strong directionality of heat conduction, detailed knowledge is required of the thermal interaction between the circuit elements. At the boundaries of film elements, the atomic vibration and electron motion are to be dispersed, reflected and transmitted, and the heat conduction both in the film thickness direction and along the film is greatly affected by the boundaries. For superconducting materials, these features are controlled by the boundary effects of atomic vibration and electron motion at lower and higher temperatures than the critical temperature, respectively. The size of grains or film thickness at which these effects are dominated is of the order of 100nm, being increased inversely proportional to the third and fourth power of temperature for metal-like and semiconductor-like heat conduction, respectively. The features decide the thermal limit of integration circuit in size and density.3. Thermal and electromagnetic interaction between circuit elements : The critical electric current dominates the stability of superconduction, being a function of the temperature and the associated magnetic field. The critical current is determined by the area integration of the local critical current density in the cross section normal to the current. The temperature field can be predicted by considering both the thermal features of directional heat conduction and the boundary effects. For a simple system of integrated system, the computation result shows that the size and configuration effects control the thermal limit of the integration. Less