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A novel alloy (Tantalum Carbide) for metal gate deposited by Ion Beam Sputtering for CMOS 45 nm device

Olivier Riche 1,3Christophe Dubarry 2Pierre Garrec 2Vincent Cosnier 1

1. STMicroelectronics, 850 rue Jean Monnet, Crolles CEDEX 38926, France
2. CEA (LITEN), 17 rue des Martyrs, Grenoble 38054, France
3. CEA (LETI), 17 rue des Martyrs, Grenoble 38054, France

Abstract

Since the MOSFET gate lengths scale down to 50 nm and below, it appears 2 major problems: the first one is the increase of leakage current and the second one is the polysilicon gate electrode depletion induces an additional capacitance [1]. To solve the first issue high-k dielectric maybe a solution since for the same electrical thickness. To solve the problem of depletion (valid for the semiconductors) the solution is containly the use metal gate. In this study, we will use Tantalum carbide (TaxCy). TaxCy [2] electrode is a ve metal candidate. In this work, the influence of the sputtering conditions was studied in order to optimise the value of work function.

TaxCy films were prepared by Ion Beam Sputtering with a tantalum target and a mixture of argon and methane. The material is tantalum carbide TaxCy of 10 nm thickness deposited on dielectric gate. All the samples are deposited at room temperature. The physicochemical characterizations used for TaxCy alloys are: X-rays difraction, SIMS, RBS and XRR.A relation between the carbon rate, the phase of TaxCy formed and the work function was established.

[1] S.E. Thompson, R.S. Chau, T. Ghani et al., IEEE Transactions for Semiconductor Manufacturing, Vol.18, n°.1, pp. 26-36, 2005.

[2] J.K. Schaeffer et al; 2004-International-Electron-Dispositifs-Meeting-IEEE - 2005: 287-90

 

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Presentation: Oral at E-MRS Fall Meeting 2006, Symposium A, by Olivier Riche
See On-line Journal of E-MRS Fall Meeting 2006

Submitted: 2006-05-15 07:58
Revised:   2009-06-07 00:44