MONTE-CARLO SIMULATION OF 2-DIMENSIONAL IMPLANTED DOPANT DISTRIBUTIONS AT MASK EDGES

Two-dimensional implanted dopant distributions at mask edges are studi ed using the Monte Carlo code IMSIL. The models implemented in the pro gram are reviewed. An empirical model of electronic stopping describes correctly the range of channeled B, P, and As ions in a wide energy r ange. The damage model takes defect recombination into account but doe s not require the simulation of recoil cascades. Two-dimensional dopan t distributions are calculated by randomly selecting the starting poin ts of the ions between two positions defining a mask opening. The simu lation results show that the penetration below the mask is larger than expected and that a Gaussian function is inappropriate to describe th e lateral distribution function. The discrepancy increases with decrea sing implantation energy. The dependence of the two-dimensional profil es on mask edge orientation, tilt angle, and ion species, and the infl uence of a screening oxide are investigated.