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Development of Ultra-smooth Si Surface by the Control of SiO_2/Si Interface Formation on an Atomic-Scale

原子尺度控制SiO_2/Si界面形成开发超光滑Si表面

基本信息

批准号：
08455023
负责人：
HATTORI Takeo
金额：
$ 4.99万
依托单位：
Musashi Institute of Technology
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
1996
资助国家：
日本
起止时间：
1996 至 1997
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-08455023/
关键词：
silicon oxide Si-SiO_2 interface structure atomic-scale layr-by-layr oxidation of silicon oxidation reaction valence band valence band discontinuity

项目摘要

In order to form atomically flat silicon oxide films, it is essentially important to use atomically flat silicon substrates and the layr-by-layr oxidation process. First, 200-nm-thick thermal oxide films were formed in dry oxygen at 1000ﾟC.Second, this oxide films were removed by buffered hydrofluoric acid. Third, on silicon substrates thus obtained silicon films were epitaxially grown by the gaseous reaction of SiHCL_3 at 1100ﾟC followed by the cooling in hydrogen gas until the substrate temperature decreases to be smaller than 400ﾟC.the silicon substrates thus obtained were maintained in nitrogen gas. Fourth, hydrogen-teminated Si(III)-1*1 and Si(100)-2*1 were obtained by removing native oxides, which were grown in nitrogen gas during relativelely long storage time, in dilute hydrofluoric acid. Hydrogen-terminated Si(III)-1*1 surface was also prepared by treating silicon substrates, which were obtained after the second procedure described above, in 40% NH_4F solution. In order to form uniform oxide film, the 0.6-nm-thick preoxides were grown in 1 Torr dry oxygen at 300ﾟC without breaking Si-H bonds. Through this preoxide thermal oxides were grown in 1 Torr dry oxygen at more than 600ﾟC.The height of protrusions on thermal oxide films thus formed on Si(III) and Si(100) surfaces are smaller than the height of two atomic steps, that is, 0.314 nm and that of single atomic step, that is 0,135 nm, respectively. Especially, the extremely flat oxide films were formed on Si(100). From the correlation between surface microroughness and SiO_2/Si interface structures the SiO_2/Si(100) interface is expected to be extremely flat and can be the ultimate interface which will be used in the most advanced MOSFET in the future. These results were obtained from the atomic-scale observation of surface morphologies of oxide films using noncontact-mode atomic force microscope and the measurement of interface structures using X-ray photoelectron spectroscopy.

为了形成原子级平坦的氧化硅膜，使用原子级平坦的硅衬底和逐层氧化工艺是非常重要的。首先，在1000 ℃的干燥氧气中形成200 nm厚的热氧化膜。其次，通过缓冲氢氟酸去除该氧化膜。第三，通过SiHCL_3在1100 ℃下的气体反应，然后在氢气中冷却，直到衬底温度降低到小于400 ℃，在由此获得的硅衬底上外延生长硅膜。将由此获得的硅衬底保持在氮气中。第四，通过在稀氢氟酸中去除在氮气中在相对长的储存时间内生长的自然氧化物，获得氢端化的Si（III）-1 1和Si（100）-2 1。通过在40%NH_4F溶液中处理经上述第二步骤后得到的硅衬底，也制备了氢封端的Si（III）-1 1表面。为了形成均匀的氧化物膜，0.6 nm厚的预氧化物在300 ℃下在1 Torr干燥氧气中生长而不破坏Si-H键。通过该预氧化物，热氧化物在1 Torr干燥氧气中在高于600 ℃下生长。由此在Si（III）和Si（100）表面上形成的热氧化物膜上的突起的高度分别小于两个原子台阶的高度，即0.314nm和单个原子台阶的高度，即0.135nm。特别地，在Si（100）上形成非常平坦的氧化膜。从表面粗糙度与SiO_2/Si界面结构的关系来看，SiO_2/Si（100）界面是非常平坦的，是未来最先进的MOSFET的最终界面。这些结果是从使用非接触式原子力显微镜和使用X射线光电子能谱测量的界面结构的氧化物膜的表面形貌的原子尺度观察。