Jpn. J. Appl. Phys. 47 (2008) pp. 2464-2467  |Previous Article| |Next Article|  |Table of Contents|
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Novel Contact-Plug Process with Low-Resistance Nucleation Layer Using Diborane-Reduction Tungsten Atomic-Layer-Deposition Method for 32 nm Complementary Metal–Oxide–Semiconductor Devices and Beyond

Akie Yutani, Kazuhito Ichinose, Kazuyoshi Maekawa, Koyu Asai, and Masayuki Kojima

(Received October 1, 2007; accepted January 18, 2008; published online April 25, 2008)

The effect of employing diborane (B₂H₆) instead of silane (SiH₄) in a tungsten (W) atomic layer deposition (ALD) nucleation layer on contact resistance is studied. A low resistance of 50–70 Ω in a 32-nm-node contact with a diameter of about 50 nm is achieved with optimized barrier and nucleation processes. This result indicates that the resistance required for 32 nm complementary metal–oxide–semiconductor (CMOS) devices can successfully be satisfied without employing a copper plug process. It is revealed that a W film with a B₂H₆-reduced nucleation layer has a larger grain size and a lower fluorine concentration in nucleation W and barrier metal layers, resulting in a lower resistivity than that with a SiH₄-reduced nucleation W layer. On the other hand, the B₂H₆-reduced nucleation process still shows a poorer crystallization and a higher fluorine concentration in the filling W layer than the SiH₄-reduced nucleation process. We revealed that a further decrease in the resistivity of a W film with the B₂H₆ nucleation process is achieved by improving these issues.

URL: http://jjap.jsap.jp/link?JJAP/47/2464/
DOI: 10.1143/JJAP.47.2464

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