Coupled atomistic 3D process/device simulation considering both line-edge roughness and random-discrete-dopant effects

We developed new simulation tools for the precise design of sub-100nm MOSFETs. The intrinsic statistical nature of these devices is expressed as fluctuations in device characteristics. Line-edge-roughness (LER) is incorporated in the structural variations in polysilicon gate masks for halo and source/drain-extensions implantations. The statistical nature of these discrete dopant distributions can be automatically included in the simulation by using Monte Carlo procedures for ion implantation and dopant diffusion/activation processes with different computationally generated LER patterns for each individual device. Our 3D device simulations were based on the classical drift-diffusion approach in which electrostatic potentials are constructed from the long-range Coulombic components of individual dopant atom potentials. Using a 3D atomistic approach to both process and device simulation enabled us to closely examine the coupling effects of the most significant sources of fluctuation, i.e. line-edge-roughness and random-discrete-dopants in the context of practical fabrication processes.