1989 Fiscal Year Final Research Report Summary
The precise analysis of silicide reactions at metal/silicon interface by TEM
| Project/Area Number |
63550026
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| Research Category |
Grant-in-Aid for General Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Research Field |
Applied materials
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| Research Institution | Okayama University of Science |
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Principal Investigator |
YOKOTA Yasuhiro Okayama University of Science, Faculty of Science, Lecturer, 理学部, 講師 (50200902)
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| Project Period (FY) |
1988 – 1989
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| Keywords | Pt-silicide / silicide reaction / cross-sectional TEM / ion-milling / projections |
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| Research Abstract |
The initial stage of the reaction process forming the platinum silicide at Pt/Si (111) interfaces have been investigated by a high resolution electron microscope in both "flat-on" and "cross-sectional" mode.
The formation process of platinum silicide (PtSi) was observed in a cross- sectional specimen. A cross-sectional micrograph of the Pt-Si interface of as- deposited specimen shows above the substrate silicon, 3-4 nm oxide layer is seen under the polycrystalline film of metal platinum. The grain size of the platinum film is about 5-10 nm in diameter. The structure image of the Pt-Si interface after 30 min was obtained. The platinum layer was separated in two parts. At the upper part, metal platinum remained was found together with silicide. Native oxide layer has moved up from the interface. Pt-silicide and metal Pt mixed together and formed spheres. The middle layer consists only platinum silicide (PtSi) and few native oxide was found at the original interface. As the result of the s
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ilicide reaction, the thickness of the layer containing platinum increases from llnm to 18 nm. Some stage of the reaction processes under the irradiation of 200kV electron beam was observed. During a high resolution EM observation without heating, silicide formation was taken place. In the first stage, Pt metal layer (thickness = 15nm) was separated by thin native oxide layer. The arrow shows the same point of the silicon substrate. The silicide layer react with substrate and went into the substrate Si and then the interface of the silicon side became wavy. Separation of the upper part and the middle part became more clear.
As the result of the series observation, the reaction processes are summarize as follows. 1. Si atom diffuse through the native oxide layer. 2. Silicide reaction is taken place at the bottom part of the Pt-metal. 3. Native oxide layer moves from the interface. 4. Remained Pt metal and silicide are mixed together and form the upper part of the film which make sphere like structures. 5. Pt-silicide contacts with Si directly. After the reaction proceed more, a epitaxial PtSi film will be formed.
At the process of specimen preparation, ion milling of the Si wafer were also investigated using cross-sectional TEM. Less
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