The role of carbon and dysprosium in Ni[Dy]Si:C contacts for schottky-barrier height reduction and application in N-channel MOSFETs with Si:C source/drain stressors

Abstract

We clarify the role of carbon and dysprosium in nickel-dysprosium-silicide (Ni[Dy]Si:C) contacts formed on silicon:carbon (Si1-y}Cy or Si:C) for Schottky-barrier height (SBH) reduction. Carbon-induced energy bandgap Eg narrowing and the segregation of dysprosium (Dy) at the Ni[Dy]Si:C/Si:C interface were shown to be responsible for SBH reduction in this paper. First, we show that electron barrier height (ΦB N) reduction of up to 69 meV (or 10.3%) for NiSi can be achieved with the scaling of substitutional carbon Csub concentration from 0% to 1.0%. Second, new evidence revealing the segregation of Dy-based interlayer at the Ni[Dy]Si:C/Si:C interface and an additional 321 meV (or 53%) reduction in ΦB N for NiSi:C are presented. This could be due to charge transfer at the Ni[Dy]Si:C/Si:C interface. The successful modulation of ΦB N for Ni[Dy]S:C translates to an effective 41% reduction in device REXT, resulting in improved drive current performance. This opens new avenues to optimize the Si1-yCy contact interface for extending transistor performance in future technological generations. © 2009 IEEE.