Gate Oxide Reliability Characterization of Tungsten Polymetal Gate with Low-Contact-Resistive WSix/WN Diffusion Barrier in Memory Devices

概要

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Gate oxide reliability characteristics using different diffusion barrier metals for a tungsten polycrystalline silicon (poly-Si) gate stack were investigated in detail. The insertion of a thin WSix layer in a tungsten poly gate stack could effectively relieve the mechanical stress of a gate hardmask nitride film during a post thermal process, which contributes to better gate oxide reliability and the stress-immunity of the transistor. This insertion could also prevent the formation of a Si–N inter-dielectric layer, which could lower the contact resistance between poly and tungsten effectively. A W/WN/WSix/poly gate stack could be a promising candidate for a future W poly gate that shows reliable high-speed characteristics in dynamic random access memory applications.
2007-11-15