Phase and Composition Control of Ni Fully Silicided Gates by Nitrogen Ion Implantation and Double Ni Silicidation

概要

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The phase and composition control of a Ni fully silicided (Ni-FUSI) gate electrode is investigated to achieve a wider process window for complementary metal–oxide–semiconductor (CMOS) device integration. We performed nitrogen ion implantation (N2 I/I) on polycrystalline silicon (poly-Si) prior to Ni deposition only for an n-MOS gate. The implanted nitrogen in the poly-Si layer suppresses the reaction of Ni and Si. As a consequence, the process temperature for Ni silicidation increased by ${\sim}20$ °C compared with that in the case without implantation. It was also found that the grain size of the Ni silicide found in the N2 I/I-treated poly-Si layer is smaller, possibly due to nitrogen atoms bound to Si and/or cavities generated inside the poly-Si layer. We also propose double Ni silicidation for fabricating a p-MOS gate, where a Ni-rich silicide was formed by carrying out an additional Ni deposition and annealing on a Ni silicide film. The Ni-rich silicide was evaluated in terms of X-ray diffraction patterns and flat band voltage shifts on capacitance–voltage measurement. Combining these techniques will enable the development of an optimized process integration scheme for CMOS devices.
Published by the Japan Society of Applied Physics through the Institute of Pure and Applied Physicsの論文
2008-04-25