極薄GeO2界面層を有するZr系high-k/Geゲートスタック構造の形成

概要

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Zr-based high-permittivity (high-k) film/Ge gate stack structure with ultra thin GeO2 interface layer (IL) was fabricated by ultra-thin bi-layer (SiO2/GeO2) passivation on Ge combined Zr/SiO2 deposition and subsequent post deposition annealing (PDA). The best value of effective oxide thickness (EOT) was 1.1 nm. It was clarified that the interface state density (Dit) was decreased by nitrogen ions generated during TiN metal-gate deposition. We also investigated the effect of post-metallization annealing after Al deposition (Al-PMA). The Al-PMA was found to be very effective for a decrease in Dit. By using effects of nitrogen ions and Al-PMA, Al/TiN/ZrSiO/GeO2/Ge structure with Al-PMA at 400 oC showed EOT of 1.7 nm and Dit of 1×1011 cm-2eV-1 at around midgap.