2006 Fiscal Year Final Research Report Summary
Improvement of polycrystalline silicon for thin film-type information devices using hydrogenation and Raman spectroscopy
| Project/Area Number |
17560284
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Electronic materials/Electric materials
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| Research Institution | Shimane University |
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Principal Investigator |
KITAHARA Kuninori Shimane University, Interdisciplinary Faculty of Science and Engineering, Professor, 総合理工学部, 教授 (60304250)
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| Project Period (FY) |
2005 – 2006
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| Keywords | poly-Si / amorphous silicon / grain boundary / defect / hydrogen / Raman scattering / thin film transistor |
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| Research Abstract |
Polycrystalline silicon (poly-Si) thin films were investigated as material of thin film transistors (TFT) for thin film type information devices. It has been known that defects in poly-Si are terminated by hydrogenation leading to improvement of device performance. However, the relationship between hydrogen and defects is complicated. This study has been performed comparing the properties of amorphous silicon (a-Si) and laser-crystallized poly-Si.
Hydrogenation was performed by catalytic method being plasma damage free. Effects of high-pressure water-vapor heat treatment (HPWVHT) were also examined. Characterization was performed mainly by Raman spectroscopy. Purity of a-Si was confirmed by electrical measurement..
TO mode width was varied with termination situation at dangling bonds (DB) in a-Si. Thus, it was confirmed that structure ordering of a-Si was varied by hydrogenation. HPWVHT caused hydrogen termination of a part of DB. For poly-Si films containing amorphous component, structural ordering of crystal component was improved by incorporation of hydrogen atoms. Thus, it was shown that structure of residual amorphous was relaxed by incorporated hydrogen atoms leading to relaxation of stress in neighboring crystalline component.
For fully crystallized poly-Si films, hydrogen termination situation of DB at defects was examined by using Secco etching. Because chemical etching includes electro-chemical kinetics, charged state of DB can be analyzed. For un-hydrogenated films, DB was intensively etched leading to relaxation of stress. That is attributed to penetration of etching solution through defects in garins leading to pooling of grains from under layer. For hydrogenated films, no erosion at GB was found. Peeling of films were not found. Moreover etching rate was decreased. Thus, it was found that hydrogenation protects not only GB but also defects in grains.
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