Low-Temperature Deposition of Dielectric Films Using Synchrotron Radiation-Assisted Gas-Source CVD

本文研究了利用同步辐射辅助化学气相沉积（CVD）技术在低温下沉积介质薄膜的方法。该方法在真空紫外（VUV）区对清洁的半导体表面进行SR辐照，同时向表面注入源气体，从而增强了源气体的光致分解和半导体表面的化学反应，这对于沉积高质量的介质膜以产生清洁、化学稳定的半导体表面是非常重要的。因此，我们研究了以下Si表面的清洗工艺：（1）通过SR辐照去除Si上的自然氧化物，（2）使用紫外（UV）臭氧去除碳污染，和（3）用稀氢氟酸（HF）溶液清洗Si表面。我们已经阐明了氢终止的硅表面的紫外臭氧氧化的初始阶段。此外，红外光谱测量表明，在HF溶液中处理的Si表面的微观粗糙度强烈地依赖于溶液的pH值，SR诱导的硅醇盐如正硅酸乙酯（TEOS）吸附在Si表面上的反应进行了研究，光子刺激脱附（PSD），光电子能谱和红外（IR）吸收光谱。我们观察到由于SR照射，醇盐分子中的烷氧基的分解。光电子能谱和红外光谱的测量证实了ST在真空紫外区分解醇盐分子形成氧化硅膜。在这项研究中，我们发现醇盐是一类很有前途的源材料的氧化硅形成。

We have investigated the method of depositing dielectric films at low temperature using synchrotron radiation (SR)-assisted chemical-vapor-deposition (CVD). In the method investigated here, a clean semiconductor surface is irradiated by SR in the vacuum ultraviolet (VUV) region while dosing the surfaces with source gases, thereby enhancing both photon-induced decomposition of source gases and chemical reactions on the semiconductor surface.It is quite important for deposition high-quality dielectric film to produce a clean, chemically stable semiconductor surface. We have therefore investigated the following cleaning processes of Si surfaces : (1) removal of native oxide on Si by SR irradiation, (2) Removal of carbon contamination using ultraviolet (UV) ozone, and (3) Cleaning of Si surface with dilute hydrofluoric acid (HF) solution. We have elucidated the initial stages of UV ozone oxidation of hydrogen-terminated Si surfaces. Futhermore, it was demonstrated with infrared spectroscopic measurements that microscopic roughness of Si surface treated in HF solution strongly depends on the pH of the solution.SR-induced reactions of silicon alkoxides such as tetraethoxysilane (TEOS) adsorbed on Si surface have been investigated using photon-stimulated desorption (PSD), photoemission and infrared (IR) absorption spectroscopy. We observed the decomposition of the alkoxyl group in alkoxide molucules due to SR irradiation. It was confirmed with photoemission and IR measurements that ST in the VUV region decomposes alkoxide molecules to form silicon oxide film. In this study, we found that alkoxide is a promising class of source materials for silicon oxide formation.