2002 Fiscal Year Final Research Report Summary
Preparation of Ta Solid Solution Anodized Capacitor and Evaluation of its Reliability
| Project/Area Number |
13650329
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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 | Kitami Institute of Technology |
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Principal Investigator |
SASAKI Katutaka KIT, Faculty of Eng., Prof., 工学部, 教授 (80091552)
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| Co-Investigator(Kenkyū-buntansha) |
KAWAMURA Midori KIT, Faculty of Eng., Research Associate, 工学部, 助手 (70261401)
ABE Yoshio KIT, Faculty of Eng., Asso. Prof., 工学部, 助教授 (20261399)
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| Project Period (FY) |
2001 – 2002
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| Keywords | Hf anodized film / Zr anodized film / Ta - Zr anodized capacitor / thin film capacitor / Schottky effect / Poole-Frenkl conduction / high permittivity / high heat - proof capacitor |
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| Research Abstract |
Electrical properties of anodic oxide films of Hf and Zr have not yet been investigated sufficiently, although HfO_2 and ZrO_2 films are recently attracted much attention as high -k materials in Si-LSI MOS devices. Then, we investigated fundamentally the capacitor properties and the leakage current properties of anodized capacitors of Hf and Zr films and compared with that of Ta anodized capacitor. As a result, it is revealed that the capacitor properties of both Hf and Zr anodized films are superior to that of Ta anodized film, because capacitors with low - loss properties and high permittivity are obtained, even if anodized thickness becomes very thin. In addition, we found that the electrical conduction mechanisms of Hf anodized film was due to the Schottky effect, while that of Zr anodized film was due to the Poole-Frenkel conduction. Furthermore, it is confirmed that the thermal stability of Hf anodized capacitor is superior to that of Zr anodized capacitor.
Next, we examined the capacitor properties and the leakage current properties of anodized film of Ta - Zr alloy as a solid solution, from the viewpoints of reduction effect of oxide thickness and heat - proof properties. As a result, it is concluded that the low - loss capacitor with high permittivity and high heat-proof properties can be realized, using this Ta -Zr anodized capacitor, in spite of very thin oxide thickness state. We speculated that the reason of the high reliable properties may be ascribed to the alloying effect of Ta with Zr and the change of conduction mechanism from Poole-Frenkel to Schottky conduction.
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