Ruthenium based metals using atomic vapor deposition for gate electrode applications

Abstract

The impacts of ruthenium-based metal gate electrodes (Ru, RuOx, RuSiOx) with atomic vapor deposition (AVD) on flatband voltage (V-FB) and equivalent oxide thickness (EOT) are demonstrated using a low temperature (<400 degrees C) process. Increasing thickness of Ru and RuOx exhibits higher V-FB, attributed to filling oxygen vacancies [V-o] in high-k gate dielectric with oxygen supplied from AVD metal gate electrodes upon annealing. Ru is efficient to attain a higher work-function and thinner EOT compared to RuOx and RuSiOx. Subsequent physical-vapor-deposition (PVD) TiN capping on AVD metals blocks oxygen out-diffusion, leading to higher V-FB than PVD W or AVD TiN capping.