1998 Fiscal Year Final Research Report Summary
Development of Low-Resistivity Contact Materials for Future ULSIs
| Project/Area Number |
08505001
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| Research Category |
Grant-in-Aid for Scientific Research (A)
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| Allocation Type | Single-year Grants |
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| Section | 展開研究 |
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| Research Field |
表面界面物性
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| Research Institution | Nagoya University |
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Principal Investigator |
YASUDA Yukio Grad.Schhol ofd Eng., Nagoya Univ., Professor, 工学研究科, 教授 (60126951)
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| Co-Investigator(Kenkyū-buntansha) |
SUGURO Kyoich Toshiba Co.Ltd., Senior Researcher, マイクロエレクトロニクス技術研究所, 主任研究員
IWANO Hirotaka Grad.Schhol ofd Eng., Nagoya Univ., Research Assist., 工学研究科, 助手 (50252268)
ZAIMA Shigeaki CCRAST,Nagoya Univ., Professor, 先端技術共同研究センター, 教授 (70158947)
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| Project Period (FY) |
1996 – 1998
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| Keywords | Contact / Metal / Si interface / SiGe / Schottky barrier / ULSI |
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| Research Abstract |
We have investigated the formation technology of ohmic contacts with very low resistivity for future ULSI devices, such as the control of Schottky barrier heights at metal/Si interfaces, the very-high impurity doping and the surface reaction control using hydrogen termination. The main results obtained by this study are as follows :
(1) We have introduced a SiGe interlayer at the metal/Si interface in order to control the interfacial barrier height. In the case of Ti/SiGe/Si (1O0) , Ti_5Ge_3, C49-TiSi_2 and C54-Ti (Si_1-_yGe_y) _2 are produced at 580ﾟC, 700ﾟC and >750ﾟC by rapid thermal annealing for 30 sec. It is found that C54-Ti(Si_1-_yGe_y)_2 is a low resistivity phase as well as C54-TiSi_2. Furthermore, the bandgap narrowing and the lowering of Schottky barrier heights are observed for Ti/SiGe/Si (l0O) systems, since Ge-rich SiGe layers are formed as a result of solid-phase reaction at the metal/SiGe interface.
(2) The contact formation process using H-termination treatments has been developed and it is confirmed to be able to form interfaces with good electrical characteristics. In the case of Ti/p-SiGe/p-Si (100) contacts, it can be found that the trap density is reduced and a nearly idealistic interface is formed by annealing for 30 sec using RTA processes. On the other hand, an increase in leakage current is observed by RTA for n-type samples.
(3) The correlation between contact resistivities and B doping concentrations has been examined in order to clarify a maximum doping concentration at metal/Si interfaces. The doping concentration about 2x10^<20> cm^<-3> is realized, which is very close to the solid solubility of B atoms in Si, and the contact resistivity can be explained by the theoretical calculation including the effect of impurity band formation.
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