Jpn. J. Appl. Phys. 45 (2006) pp. L1289-L1292 |Previous Article| |Next Article| |Table of Contents|
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Modified Oxygen Vacancy Induced Fermi Level Pinning Model Extendable to P-Metal Pinning
1Semiconductor Leading Edge Technologies, Inc. (Selete), Tsukuba, Ibaraki 305-8569, Japan
2Graduate School of Pure and Applied Sciences, University of Tsukuba, Tsukuba, Ibaraki 305-8573, Japan
3Advanced Electronic Materials Center, National Institute for Materials Science, Tsukuba, Ibaraki 305-0047, Japan
4CREST, Japan Science and Technology Agency, Kawaguchi, Saitama 332-0012, Japan
5Graduate School of Engineering, Osaka University, Suita, Osaka 565-0871, Japan
(Received September 18, 2006; accepted November 7, 2006; published online December 8, 2006)
Typical p-metals show similar effective work functions close to p+ polycrystalline silicon (poly-Si) pinning position irrespective of materials after high-temperature process. We found that this phenomenon can be explained by the modified Vo model taking into account the effect of Si substrate. Oxygen absorption by Si substrate and subsequent electron transfer to metal electrode clearly explain the p-metal Fermi level pinning as well as p+ poly-Si pinning. In addition, unsuppressed Fermi level pinning by insertion of barrier layer at p+ poly-Si/barrier layer/high-k gate stack, which is one of the open issues concerning p+ poly-Si pinning, has the same overall reaction scheme. The modified model also consistently explains this phenomenon.
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