Mechanism of Hf-silicide formation at interface between poly-Si electrode and HfO2/Si gate stacks studied by photoemission and x-ray absorption spectroscopy
Mechanism of Hf-silicide formation at interface between poly-Si electrode and HfO2/Si gate stacks studied by photoemission and x-ray absorption spectroscopy
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DOI：
10.1063/1.2206610
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发表时间：
2006-06
影响因子：
3.2
通讯作者：
H. Takahashi;J. Okabayashi;S. Toyoda;H. Kumigashira;M. Oshima;K. Ikeda;G. L. Liu;Zhi Liu;K. Usuda
中科院分区：
文献类型：
--
作者：
H. Takahashi;J. Okabayashi;S. Toyoda;H. Kumigashira;M. Oshima;K. Ikeda;G. L. Liu;Zhi Liu;K. Usuda
我们已经研究了硅化机制的化学反应在多晶Si（poly-Si）scinHfO 2 scinSi栅叠层通过退火在真空中使用光电子能谱和X射线吸收光谱。Si 2 p、Hf 4f和O 1 s的高分辨率光电子能谱表明，Hf-硅化物的形成始于700°C的低温，并且Hf硅酸盐也在多晶硅电极和HfO 2之间的界面处形成。在HfO 2和Si衬底的界面处形成金属铪硅化物，改变了Si衬底上的能带偏移。我们已经发现，多晶硅电极促进HfO 2和Si衬底之间的界面反应，而在HfO 2层的结晶是独立的硅化物的形成。考虑吉布斯自由能的热力学分析也证实了基于光电子能谱的硅化机理。
We have investigated the mechanism for silicidation by chemical reactions at polycrystalline-Si (poly-Si)∕HfO2∕Si gate stacks by annealing in ultrahigh vacuum using photoemission spectroscopy and x-ray absorption spectroscopy. Si 2p, Hf 4f, and O 1s high-resolution photoemission spectra have revealed that a Hf-silicide formation starts at as low temperature as 700°C and that a Hf silicate is also formed at the interface between poly-Si electrodes and HfO2. The metallic Hf silicide is formed at the interface between HfO2 and Si substrates, which changes the band offsets on Si substrates. We have found that poly-Si electrodes promote the interfacial reaction between HfO2 and Si substrates, while the crystallization in a HfO2 layer is independent of the silicide formation. The silicidation mechanism based on photoemission spectra is also confirmed from the thermodynamical analysis considering the Gibbs’ free energy.