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Study on the formation of CoSi_2/Si(100) heterostructures by reactive epitaxial growth

反应外延生长CoSi_2/Si(100)异质结的研究

基本信息

批准号：
11450010
负责人：
ZAIMA Shigeaki
金额：
$ 9.28万
依托单位：
Nagoya University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
1999
资助国家：
日本
起止时间：
1999 至 2001
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-11450010/
关键词：
CoSi_2 epitaxial growth salicide technique STM TEM two-step growth multiple nucleation and layer growth twin structure 反応機構反応バリアサーファクタント効果多層多核成長界面反応過程走査型トンネル顕微鏡 SK成長

项目摘要

CoSi_2 is expected as an epitaxial contact in ULSI devices since the CoSi_2 film can be epitaxially grown on a Si(100) surface. In this project, in order to realize a salicide technique, by which a 20-nm-thick epitaxial CoSi_2 film required for Si-ULSI processes can be formed on a Si(100) surface, we have clarified the solid-phase reaction at Co/Si interfaces and its physical factors dominating the reactions, using scanning tunneling microscopy and transmission electron microscopy. In addition, we have developed a two-step growth method and investigated the formation mechanisms of the first-step ultra-thin CoSi_2(100) epitaxial film. For improving the coverage and the flatness of the ultra-thin CoSi_2(100) film, additional elements such as O, Sb, Ge and Al have been introduced as an intermediate layer in the CoSi_2(100)/Si(100) epitaxial growth and we have clarified the effects of the additional elements on the epitaxial growth mechanisms.( 1 ) CoSi_2(100) films are epitaxially grown o … More n Si(100) surfaces in a similar growth manner of a Stranski-Krastanov growth mode. Defects and steps on the Si(100) surface act as nucleation sites of a CoSi_2(100) film, and multiple nucleation and layer growth is enhanced, resulting in the improvement of the film coverage.( 2 ) In the two-step growth, no 3-dimensional CoSi_2 island with {115} facets is observed, and the depth of pinholes and channels on the CoSi_2(100) surface is much less than that in reactive deposition epitaxy. It is considered that the step structures on the CoSi_2(100) film surface covered with Si atoms play a role of a nucleation site. As a result, epitaxial growth with multiple nucleation and layer growth proceeds during Co deposition. In addition, the first-step ultra-thin CoSi_2(100) film enhances the layer growth and suppresses the diffusion of Si atoms from the substrate around the pinhole, which leads to the realization ofa flat surface.( 3 ) In the case of O and Al atoms used as an intermediate layer, the film coverage and flatness are significantly improved. Especially, in the 470℃ solid-phase epitaxy with O atoms, a pinhole-free and atomically-flat CoSi_2(100) film can be realized. In the case of 3-ML-thick Al interlayer film, a CoAl film randomly with Si atoms in its substitutional positions is formed. On the other hand, in the cases of a Sb and Ge interlayer, CoSi_2 islands with a twin structure are observed. Less

由于CoSi_2薄膜可以在Si（100）表面外延生长，因此CoSi_2有望成为ULSI器件的外延接触。本课题为实现在Si（100）表面形成Si- ulsi工艺所需的20 nm厚外延CoSi_2膜的盐化技术，利用扫描隧道显微镜和透射电镜研究了Co/Si界面固相反应及其主导反应的物理因素。此外，我们还开发了一种两步生长方法，并研究了第一步超薄CoSi_2（100）外延膜的形成机制。为了提高超薄CoSi_2（100）薄膜的覆盖度和平整度，在CoSi_2(100)/Si（100）外延生长中引入了O、Sb、Ge和Al等元素作为中间层，并阐明了这些元素对CoSi_2(100)/Si（100）外延生长机制的影响。(1) CoSi_2（100）薄膜以类似Stranski-Krastanov生长模式的外延方式生长在…More n Si（100）表面上。Si（100）表面的缺陷和台阶作为CoSi_2（100）膜的成核位点，增强了CoSi_2（100）膜的多次成核和层生长，从而提高了膜的覆盖率。(2)在两步生长中，没有观察到带有{115}晶面的三维CoSi_2岛，CoSi_2（100）表面的针孔和沟道深度远小于反应沉积外延。认为在覆盖有Si原子的CoSi_2（100）薄膜表面的阶梯结构起了成核位的作用。因此，在Co沉积过程中，外延生长以多核和层状生长进行。此外，第一步超薄CoSi_2（100）薄膜促进了层的生长，抑制了Si原子在针孔周围从衬底扩散，从而实现了表面的平坦化。(3)以O原子和Al原子作为中间层时，膜的覆盖度和平整度均有显著提高。特别是在470℃的O原子固相外延中，可以实现无针孔的原子平面CoSi_2（100）薄膜。在3ml厚的Al层间膜中，形成了Si原子在其取代位置上随机分布的CoAl膜。另一方面，在Sb和Ge夹层中，观察到具有孪晶结构的CoSi_2岛。少