【作者】 布文峰；

【导师】 唐大伟；

【作者基本信息】 中国科学院研究生院（工程热物理研究所） ， 工程热物理， 2007， 博士

【摘要】 本研究的主要目的是探寻实现表面下热物性分布测量的有效方法，实现其关键技术，实现空间分布面方向微米量级，深度方向亚微米量级的测量装置研究，为今后的空间分辨率纳米量级的扫描热显微镜打下基础。在实验上采用周期半导体激光为加热源，连续半导体激光为探测光，光学显微镜物镜聚光，应用稳态的光热反射探测技术得到相应于表面温度响应的周期反射信号，此系统主要包括周期加热激光、连续探测激光、显微镜物镜、硅光电探测器、锁相放大器、微米尺度二维扫描平台。在测量原理方面，通过对于层状结构试样热传导问题进行解析，引入了传输线理论及其使用方法。为有效利用传输线理论，对能量方程组进行了Laplace变换和Hankel变换。得到解析解后，在简单情况下可通过Laplace反变换和Hankel反变换得到表面温度在空间域和频域的分布，得到加热信号与反射信号的相位差及振幅比与结构的关系，确定结构测量原理。同时开发针对此问题的逆解析算法——模拟退火算法，并根据测量结果进行热物性（导热系数，界面热阻）的计算。对实验中被测参数进行了敏感度分析。实验测量与理论分析相结合，提出微尺度表面下结构及瞬态导热性能分布的测量原理及实验方法，建立一套5～10微米分辨率的实验室用测试系统。实现微米量级尺度简单结构复合试样的结构与导热性能分布的测量。在单点测量方面，通过对不同厚度SiO₂薄膜导热系数测试的实验测量，发现98nm～322nm厚的SiO₂薄膜的导热系数低于其体参数(1.38W·m^-1·K^-1)，且与厚度有关，厚度越小，导热系数越小；Al／SiO₂之间的界面热阻与SiO₂薄膜的内部热阻数量级相当，不可忽略：SiO₂／Si之间的界面热阻可以忽略。通过对表面下埋藏物的光热反射扫描试验，发现当热波在埋藏物中的热扩散长度与埋藏物的厚度相当时，探测异物存在的敏感度最高，由此可得到埋藏物热扩散系数的数量级，精确定量地分析其数值大小时，需要准确地测量泵浦／探测光斑的直径大小、精确的电动扫描平台和精确的三维热波扩散模型。根据数值模拟结果，讨论了埋藏物深度、埋藏物和基体的热浸透率比值对于表面下热结构测量的影响。更多还原

【Abstract】 This program aims mainly at find out a feasible method to determine the subsurface thermal properties distribution, implement the key technology, set up a system with the resolution of micron in face and the resolution of submicron in depth, which are prepared for the study of nanoscale scanning thermal microscopy.With periodically modulated semiconductor laser used as the heating source, continuing semiconductor laser used as probing laser, optic microscopy objective used as focusing optics, the steady photo thermoreflectance experiments are performed. The reflectance signal corresponding to the temperature response is detected. The setup includes periodical heating laser, continuing probing laser, objective, silicon photodiode, lock-in amplifier, 2D microscale scanning stage.The multilayer heat conduction is analyzed. The transmission line theory is described and used in the solving of heat conduction equations. Using Laplace transform, Hankel transform and transmission line theory, the expression of surface temperature is deduced in Laplace domain and Hankie domain. The temperature in frequency domain and space domain can be deduced by inverse transformation accordingly. The measurement principles of thermal characteristic are determined by the functions of phase lag or amplitude ratio between heating signal and probing signal. The simulated annealing algorithm in the inverse analysis for determining the thermal conductivity and thermal boundary resistance is developed. The sensitivity of the considered parameter is analyzed.The experiment principle and method of measurement of microscale subsurface thermo characteristics distribution are described numerically and experimentally. A laboratory measurement setup with resolutions of 5-10 micron is developed. The measurement of thermo conductivity distribution of microscale composite sample isrealized.The thermal conductivities of thermally oxidized SiO₂ films of 98nm, 148nm, and 322nm in thickness deposited on Si substrate are measured. The thermal conductivity of the nano SiO₂ film is found to be less than its bulk value, and thickness dependent. The thermal boundary resistance between SiO₂ and Al coating is found to be comparable to the thermal resistance of the SiO₂ layer. The thermal boundary resistance between SiO₂ and Si can be neglected.The results of scanning sample with buried inhomogeneities show that the sensitivity is the highest when the thermal diffusion length is comparatable to the depth of the buried inhomogeneities. The order of magnitude of thermal diffusion can be deduced. Accurate dimension of diameter of heating beam and probing beam and 3D thermal wave model are necessary for determining the exact thermal diffusivity.The process of heat conduction is analyzed numerically. Based on the simulation results, various depth and effusivity of the buried inhomogeneities in the microscale subsurface structure measurement is discussed.更多还原