物理化学学报 >> 2010, Vol. 26 >> Issue (11): 3030-3034.doi: 10.3866/PKU.WHXB20101111

光化学与光谱 上一篇    下一篇

硅晶片上超薄氧化硅层厚度纳米尺寸效应的XPS 研究

赵志娟, 刘芬, 赵良仲   

  1. 中国科学院化学研究所, 北京100190
  • 收稿日期:2010-04-27 修回日期:2010-08-02 发布日期:2010-10-29
  • 通讯作者: 刘芬 E-mail:fenliu@iccas.ac.cn
  • 基金资助:

    质检公益性行业科研专项项目(200710199)资助

XPS Study of the Thickness Nanosize Effect for Ultrathin SiO2 on Si Substrate

ZHAO Zhi-Juan, LIU Fen, ZHAO Liang-Zhong   

  1. Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, P. R. China
  • Received:2010-04-27 Revised:2010-08-02 Published:2010-10-29
  • Contact: LIU Fen E-mail:fenliu@iccas.ac.cn
  • Supported by:

    The project was supported by the Special Research Foundation of Commonweal Profession for Quality Inspection, China (200710199).

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摘要：

用X射线光电子能谱(XPS)测定了一系列厚度经过国际比对准确已知的硅晶片上的超薄(1.45 nm<d<7.2nm)氧化硅膜的Si 2p 电子能谱和价带谱. 结果表明: SiO2膜厚d<2 nm 时, Si 2p 结合能最低, 其原因可归结于此时光电离空穴既有来自SiO2中的原子极化对空穴的原子外弛豫, 也有来自衬底Si 的电荷移动对空穴的屏蔽(有效屏蔽距离大约是(2.5±0.6) nm); 当d>3 nm时Si 2p 结合能增大, 此时只有来自SiO2的原子外弛豫, d较小者的Si 2p 结合能较高. SiO2的价带电子结构也与其厚度纳米尺寸效应有关: 当d<2 nm 时价带中SiO2的O 2p非成键电子峰的相对强度较强, O 2p—Si 3p和O 2p—Si 3s成键电子峰较弱.

 

关键词: 硅晶片, SiO2膜, 纳米厚度, 尺寸效应, X射线光电子能谱, 电子结合能, 价带谱, 原子外弛豫

Abstract:

X-ray photoelectron spectroscopy (XPS) was used to record the Si 2p and valence band spectra for a series of ultrathin SiO2 on Si substrate with the oxide thickness (d) ranging from 1.45 to 7.2 nm. The thicknesses of these samples were measured precisely in the international key comparison. The results show that the samples with the oxide thickness of d<2 nm have a lower Si 2p binding energy (EB ). This has been attributed to the extra-atomic relaxation provided by both the polarization of the neighboring atoms of SiO2 and charge transfer from atoms of the Si substrate to the core holes created by photoionization (the screening distance was about (2.5±0.6) nm). The EB of Si 2p increased when d>3 nm and in this case extra-atomic screening was provided by the polarization of the neighboring atoms of SiO2. The sample with a smaller d showed a higher EB for Si 2p. The valence band structure is also related to the thickness nanosize effect. The samples with d<2 nm show a higher relative peak intensity of the O 2p non-bonding electrons and lower peak intensities for the O 2p—Si 3p and O 2p—Si 3s bonding electrons from SiO2.

 

Key words: Si substrate, Silicon oxide film, Nanosize thickness, Size effect, X-ray photoelectron spectroscopy, Electron binding energy, Valence band spectrum, Extra-atomic relaxation