Modeling the impact of the vertical doping profile on FinFET SRAM V<inf>T</inf> mismatch

The basic multi-gate Vt variation model for uniform doping is extended to support a 2-region fin doping methodology that provides good agreement with Vt mismatch measurements as well as useful insights into how the non-uniform fin doping impacts the mismatch. The methodology displays good agreement for both NMOS and PMOS SRAM devices from a FinFET process. The NMOS Vt mismatch as a function of Vt is found to follow the non-uniform doping model while the PMOS Vt mismatch is higher due to both high, non-uniform doping as well as P-metal gate workfunction induced mismatch.