TwoDimensional Process Simulation Using Verified Phenomenological Models

Twodimensional (2-D) effects are becoming increasingly important in the diffusion of impurities in submicrometer silicon devices. Existing process simulators cannot accurately model some of these effects. We describe a 2-D process simulator PREDICT2 that handles implant damage effects, annealing, and lateral diffusion. PREDICT2 simulates the diffusion of impurities in silicon by using phenomenological diffusion coefficients. The phenomenological models are verified by comparing simulated and experimental results. This approach is contrasted with that of point defect-based simulators. The experimental technique for measuring impurity profiles in two dimensions is outlined. The method for generating diffusion models is then illustrated by examining 2-D phosphorus diffusion. Numerical simulations and experimental measurements are compared. The numerical methods used in the simulator are described, and directions for future work suggested.