Highly-Doped Through-Contact Silicon Epi Design at 3 nm node

Through-contact highly doped Si epi (TS Epi), in which an additional epi with higher doping is grown on top of the S/D epi, has shown promise of lower contact resistivities $(\rho_{\mathrm{c}})$ owing to reduced Schottky barrier heights (SBH) and tunneling barrier thickness [1]–[3]. We show by Non-Equilibrium Green's Function Density Functional Theory (DFT-NEGF) of TiSi/Si interface that sub $1\mathrm{e}-9\Omega-\mathrm{cm}^{2}$ are achieved for $> 2\mathrm{e}20\mathrm{cm}^{-3}$ doping in Si. In this paper, we show that TS Epi improves the $\mathrm{I}_{\mathrm{ON}}$ and ring-oscillator (RO) stage-delay by 9% and 7.4%, respectively. We show that thinner TS Epi leads to higher performance due to lower epi resistance. SD metal fill aspect ratio improvement due to TS Epi is also discussed.