| Project/Area Number |
11555088
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| Research Category |
Grant-in-Aid for Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Section | 展開研究 |
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| Research Field |
Electronic materials/Electric materials
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| Research Institution | HIROSHIMA UNIVERSITY |
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Principal Investigator |
KIKKAWA Takamaro Research Center for Nanodevices and Systems, HIROSHIMA UNIVERSITY, Professor, ナノデバイス・システム研究センター, 教授 (60304458)
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| Co-Investigator(Kenkyū-buntansha) |
SHIBAHARA Kentaro Research Center for Nanodevices and Systems, HIROSHIMA UNIVERSITY, Associate Professor, ナノデバイス・システム研究センター, 助教授 (50274139)
YOKOYAMA Shin Research Center for Nanodevices and Systems, HIROSHIMA UNIVERSITY, Professor, ナノデバイス・システム研究センター, 教授 (80144880)
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| Project Period (FY) |
1999 – 2001
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| Project Status |
Completed (Fiscal Year 2001)
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| Budget Amount *help |
¥13,700,000 (Direct Cost: ¥13,700,000)
Fiscal Year 2001: ¥1,200,000 (Direct Cost: ¥1,200,000)
Fiscal Year 2000: ¥4,500,000 (Direct Cost: ¥4,500,000)
Fiscal Year 1999: ¥8,000,000 (Direct Cost: ¥8,000,000)
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| Keywords | barium / strontium / titanium / BST / energy band / band gap / inductively-coupled-plasma / sputtering / ペロブスカイト / 高誘電率 / 集積回路 / DRAM / キャパシタ / 電極 / リーク電流 / 高誘電率膜 / 電極金属 / チタン酸バリウム / チタン酸ストロンチウム / ULSI |
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| Research Abstract |
This research was conducted for scaling of devices feature size such as capacitor and tlie performance improvement for future ULSI. In order to obtain sufficient effective dielectric constant, perovskite crystal structure barium strontium titanate (Ba,Sr)TiO_3 (BST) was investigated. Since BST is a dielctric material composed of 4 elements such as Ba, Sr, Ti and O, it is necessary to apply radio-frequency (RF) magnetron-plasma sputtering. In this research inducrtively-coupled-plasma(ICP) was applied to RF magnetron plasma. Properties of BST thin films, which were deposited by IGP-assisted RF magnetron-plasma sputtering, were investigated. It is found that the lCP-assisted RF-magnetron plasma improved the stoichiometry of the BST film. The energy band structure of the Ru/BST/Si system was investigated. It is found that the band gaps of BST and interface SiO_2 were investigated by XPS-EELS spectra and were determined as 4.30 eV and 8.95 eV, respectively. The valence band offsets for BST/Si and interface SiO_2/Si were measured by XPS and determined as 3.55 eV and 4.48 eV, respectively. Judging from the result, positive charges were trapped in the film so that the SiO_2 band was bent. The work function of Ru was 4.97 eV. Since the electron affinity was 3.57eV, the conduction band barrier height of Ru against BST was found to be 1.40 eV. Consequently, energy band structure of Ru/BST/SiO_2/Si was determined. Furthermore, electrical characteristics of BST film were investigated in terms of capacitance and leakage current. It is found that the leakage current characteristics were improved by 2 order of magnitude by introducing Ta thin interface layer deposition before BST depositiion.
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