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

We clarify the role of carbon and dysprosium in nickel-dysprosium-silicide (Ni[Dy] Si:C) contacts formed on silicon:carbon (Si1-yCy or Si:C) for Schottky-barrier height (SBH) reduction. Carbon-induced energy bandgap E-g 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 (Phi(N)(B)) reduction of up to 69 meV (or 10.3%) for NiSi can be achieved with the scaling of substitutional carbon C-sub 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 Phi(N)(B) 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 Phi(N)(B) for Ni[Dy]S:C translates to an effective 41% reduction in device R-EXT, 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.