An investigation of the two-dimensional shape of ion-implanted regions

The two-dimensional shape of arsenic ion-implanted regions in single-crystal silicon was investigated both experimentally and theoretically. Experimentally, two techniques were shown to have the necessary submicron resolution: a junction etch process and a scanning electron microscope-induced current collection method. A comparison of junction depths determined by the etch technique and the electron beam induced current technique with the depths calculated using several amorphous target codes was made. For the case of low temperature (600 °C) anneals, the etch technique agrees very well with the junction depths predicted by the amorphous target code due to Winterbon. The lateral junction locations obtained from the etch technique are in good agreement with the predictions of a two-dimensional Monte Carlo code which indicates that the arsenic does not show any significant lateral scattering under mask edges. For the high temperature (1000 °C) anneals, the etch and electron beam induced current techniques agree with each other. Comparison with arsenic-diffusion models shows that concentration-dependent effects are important.