As-ion-implantation simulation for trench structures using Monte Carlo method

This study features As-ion-implantation simulation for three-dimensional trench structures using a newly developed Monte Carlo simulation program. The calculation procedure for the two-body collision process is tabulated to substantially reduce the CPU time. The simulation offers optimized ion-implantation methods and structures for cone-shaped trench capacitors, a promising candidate for megabit DRAM capacitors. Since the incident ions are injected with a shallow angle to the sidewall surface, some of the incident ions have been found to be recoiled from the surface and reinjected into another surface or the bottom. The simulation has revealed the optimized incidence angle for general trench structures, the effect of the trench depth/width ratio on the dose distribution, and the dose distribution improvement by adding a moderate taper angle for the trench sidewall, from the uniform doping viewpoint. Based on these results, trench ion implantation was proved to be capable of achieving nearly uniform doping profiles within deviations of a factor of 2 or 3