Plasma processed ultra-thin SiO 2 interfaces for advanced silicon NMOS and PMOS devices: applications to Si-oxide/Si oxynitride, Si-oxide/Si nitride and Si-oxide/transition metal oxide stacked gate dielectrics

Abstract

The substitution of alternative gate dielectrics for thermally-grown SiO 2 and nitrided SiO 2 in aggressively scaled devices requires a significant processing change in going from thermally-grown to deposited dielectrics. This requires separate and independent steps for (i) the formation of Si-dielectric interface and (ii) the deposition of the dielectric thin film, which can be (a) Si nitride, or a Si oxynitride alloy, or (b) a high- k oxide. It is demonstrated that ultra-thin, nitrided Si–SiO 2 interface layers prepared by 300°C remote plasma processing can be effective in insulating device performance and reliability from deleterious effects associated direct deposition of alternative dielectric materials directly on to hydrogen-terminated Si surfaces. These interfaces perform equally well with Si nitride, Si oxynitride and high- k oxides, and contribute approximately 0.3–0.4 nm to the overall electrical oxide thickness (EOT), limiting aggressive scaling of EOT to approximately 0.6 nm.