SOI关键参数的光学表征技术——理论研究及工程实用化

【作者】 李林；

【导师】 俞跃辉；

【作者基本信息】 中国科学院上海冶金研究所 ， 材料物理与化学， 2001， 硕士

【摘要】 绝缘衬底上的硅（Silicon-On-Insulator，简称SOI）在近年以来受到了人们的广泛关注。在未来，基于SOI的器件所具有的优异性能，它不但将会广泛应用于如笔记本电脑、移动电话等便携式系统；而且将在石油、化工、汽车等领域大放异彩。更进一步，SOI还有望向光电集成电路，纳米尺度的快速闪存器件，乃至单电子晶体管等等一系列面向未来的半导体技术发展，具有极其光明的应用前景。SOI材料的研制，也是中国科学院“知识创新”的重要课题。 在本文中，利用SIMOX技术成功地制造了SOI材料，使用卢瑟福背散射（RBS/C）、透射电子显微镜（XTEM）和高分辨率电子显微镜（HRTEM）分析了样品的各层薄膜厚度、晶体结构的完整性以及薄膜的完整性和界面处的情况。在分析以上实验结果的基础上建立了一系列物理模型，发展了红外反射光谱（IR）来测量SOI材料的关键参数——顶层硅和氧化理层的光学厚度及均匀性，并针对各种误差的来源，进行了进一步的讨论和有效的修正，得到可信的结果。并利用俄歇电子能谱（AES）分析样品中硅和氧在样品中不同深度处的化学状态；以及在深度方向上，各元素在不同深度的变化情况。其结论很好地验证了红外反射光谱（IR）的模拟结果。 基于对以上物理模型的研究，结合现阶段使用计算机测量的广泛性，利用动态数据交换（Dynamic Data Exchange）把数据和其他处理分析的工具结合起来，可以很容易地使数据得以共享；充分利用数值求解的自适应方法，结合物理模型，计算数学对样品模型做了大量优化，很好地做到了逐步逼近、而又保证快速收敛，从而对数理方程进行了不重不漏的分析，很好地达到了数值计算的目的；利用作图分析方法，可以简便直观地得到分析结果，SOI材料的有关参数一目了然，达到了预期的结果；基于软件工程的要求，本程序编码是模块化的，易于维护，可以很容易地进行进一步的改进，对于多种情况都可以分析；具有很强的健壮性，其中的实时记录模块能对数据处理过程中的一系列中间数据进行快速保存，防止意外停电等事故，并能为其它运算提供辅助作用，而容错处理模块能对输入输出的数据进行一系列校验，防止误操作等偶发性错误，这在工程生产上有重要意义。 在以上工作中，作者建立了一套软件，用以分析SOI材料关键参数：表层硅和氧化埋层的厚度和均匀性。不但能迅速得到正确的结果，处理速度快、可靠性高，而且还易于使用，健壮性强，可维护性好。该套软件基于图形的用户界面， 摘 要亲和力强，易于使用，达到了分析501材料生产实用化的要求，并成功地应用于中国科学院“知识创新工程” 501材料实际生产的样品表征测量流程中。通过对SOl材料的生产工艺进行分析，提出了一系列可靠的反馈意见。 实践证明，该项工作能快速准确地得到501材料的关键性物理参数：表层硅和氧化埋层的厚度和均匀性，能实用于SOI材料生产工程的分析表征，具有相当的工程实用意义。 本文还对硅中注氢后退火所形成的微结构进行了一系列分析，在分析了I化S几，扩展电阻探针uRP）以及显微照片等实验结果的基础上，建立了对应的物理模型，并应用红外反射光谱UR）来测量分析纳米空洞的分布，在利用原于力显微镜（A17M）等手段加以检验的前提下，作了进一步的讨论和有效的修正。这对于用枷l广CUt工艺生产SOI材料具有很重要的意义。更多还原

【Abstract】 Silicon-On-Insulator (SQl), formed by the top Si layer, the buried SiQ2 layer and the bulk Si substrate, constitutes an interesting alternative to bulk Si for the fabrication of advanced electronic devices and integrated circuits (ICs). The technology of SQl is a powerful method for fabricating deep sub-micrometer Complementary-Metal-Oxide-Silicon devices (CMOS). The Circuits fabricated on these wafers present several advantages in relation to bulk Si technologies: low power, high density of integration, high radiation hardness and high switching speed of devices. These advantages are determined by the presence of the buried dielectric layer, which allows electrical isolation between the active region and the Si substrate, as well as between adjacent devices in the IC. There are more and more ICs based on SQl now. (100) n-type, 5?? cm silicon wafers were implanted with oxygen ions (16Q~), with enrgy from 140 to 160 KeV and dose from 4.5x 1O to l.4x10? cnf2. The temperatur of wafer during the implantation was maintained at 680 0C, The wafers were annealed at 1300 0C in an Ar ambient, mixed with 0.5% Oxygen for 5 hours. The structures of the top silicon and buried oxide layers are analyzed by Rutherford Back-scattering Spectrometry (RBS), Transmission Electron Microscope (TEM), Auger Electron Spectroscopy (AES) and Infrared Reflection (IR). RBS was used to get the information about the atomic ratio of Si/O and the crystal perfection of the top silicon layer, the thickness of buried oxide and top layer. TEM was used to analyze the micros-structure of SIMOX, including the sharpness of the interface and the existence of Si-island in the buried oxide layer. AES was applied to get the information about atomic ration of Si/O in buried oxide layer. The model based on a multi-layer stack structure is set up. An optical characterization, based on the model, has been~developed by simulation of Infrared Reflection spectrum. The key parameters of SIMQX wafers such as thickness of top silicon layer and buried oxide layer and their uniformity are obtained by this non-destructive optical characterization method. Our results prove that this method is powerful and very useful in in-line characterization of SIMOX wafer production. The RBS is used to analyze the crystalline properties of the top silicon layer, the atomic ratio of Si/Q of the buried oxide later and thickness of the top silicon layer and buried oxide layer. The results show that the crystalline structure of top layer silicon is very good. Simulated random spectra reveal that atomic ratio of Si/Q in buried oxide layer is about 1 .82.0. The interface between top silicon layer and buried oxide layer is sharp. The microstructure is examined by JEM-4000EX. The results show that the buried oxide layers are continuous and contain silicon islands. The thickness of top silicon layer and buried oxide layer is accorded with the results of RBS. HRTEM is used to analyze the lattice structure of the top silicor layer and interface between top silicon layer and buried oxide layer. The HRTEM images reveal that lattice of the top silicon layer is perfect and the interface is sharp. The chemical state of silicon in the buried oxide layer has been studied by AES. Auger peak of Si in the buried oxide layer is at 86eV, which is different from that of pure Si at 92eV or that of Si in SiQ2 at 76eV. This result reveals that the oxide in the buried layer is not pure silicon dioxide. Combined with the results of TEM, it is found更多还原