Development of Atomic-Scale, Infrared Reflection Spectroscopic Techniques for Characterization of Semiconductor Surfaces

我们已经研究和开发了一种方法，在原子尺度上的化学状态的硅晶片表面使用红外吸收光谱（IRAS）在多次内反射几何（MIR）的表征。由于其高表面灵敏度，IRAS-MIR是研究半导体表面化学性质的有力工具。本研究的主要目的是研制一套硅片在真空、空气和溶液中存放时表面化学状态的在线监测系统，并对该系统的性能进行测试，首次成功地利用该监测系统对硅片在氢氟酸（HF）溶液中存放时的表面化学状态进行了监测。我们已经证明，该表面，而沉浸在HF溶液中是不完全终止与氢和水冲洗导致完美的氢终止。使用开发的监测系统，使我们能够测量在大气环境中的Si表面的化学状态，我们还调查了在空气中储存过程中的Si表面的氧化的初始阶段。结果表明，空气中的水分对氢封端表面最上层的氧化有强烈的影响，表面Si-H键的氧化导致自然氧化膜的形成。

We have investigated and developed a method of characterizing in the atomic scale the chemical states of silicon wafer surfaces using infrared absorption spectroscopy (IRAS) in the multiple internal reflection geometry (MIR). Because of its high surface sensitivity, IRAS-MIR is a powerful tool for investigating the chemical nature of semiconductor surfaces. The main aim of this study is to develop a monitoring system for measuring in-situ the surface chemical state of silicon wafers whilestored in vacuum, air and solution, and furthermore to determine the performance of the system.As a result, we have for the first time succeeded to monitor the surface chemical states of silicon wafers during storage in hydrofluoric acid (HF) solution with the developed monitoring system. We have demonstrated that the surface while immersed in HF solution is not completely terminated with hydrogen and water rinsing leads to the perfect hydrogen termination. Using the developed monitoring system which enables us to measure the chemical state of Si surfaces in atmospheric environment, we have also investigated the initial stages of oxidation of Si surfaces during storage in air. We demonstrated that the oxidation of the topmost layr of the hydrogen-terminated surface is strongly affected by the moisture of air, and that the oxidation of the surface Si-H bonds leads to the formation of native oxide film.