STOPPING AND DAMAGE PARAMETERS FOR MONTE-CARLO SIMULATION OF MEV IMPLANTS IN CRYSTALLINE SI

Semiempirical models of electronic energy loss and damage formation fo r MeV ions (B, P, As) implanted in silicon at room temperature were in vestigated through the comparison of measurements with Monte Carlo sim ulations of both impurity and damage depth distributions. Accurate pre diction of dopant profiles in an amorphous target and in a low-dose im planted crystal is achieved by a proper parametrization of well known analytic stopping models. Moreover, to accurately describe the dynamic effects of damage accumulation in medium dose implants, a dependence on ion energy of the efficiency parameter used in the Kinchin-Pease (K P) model must be introduced in the simulation. Such a factor, determin ed by the fit of the measured integral of defect profiles, is found to decrease for P and As ions with increasing the nuclear energy release d to primary recoil atoms, apparently reaching a saturation value of a bout 0.25. Full cascade simulations show that the increasing fraction of the primary recoils energy spent in electronic processes, not consi dered in the simple KP approximation, cannot explain the observed tren d. While the empirical adjustment of damage efficiency leads to a good agreement between simulated and experimental dopant profiles, a syste matic underestimate in the depth position of the peaks of simulated da mage distributions is observed, which cannot be accounted for by simpl e ballistic transport effects. (C) 1997 American Institute of Physics.