Multiple implantations into Si: influence of the implantation sequence on ion range profiles

In successive implantations of p- and/or n-dopants the implantation sequence may affect the ion range distributions. This is demonstrated for two consecutive implantations into the [001] channel direction: (i) 35 keV B followed by 50 keV As and (ii) 50 keV As followed by 35 keV B. The defects formed in the first implantation cause enhanced dechanneling of the subsequently implanted ions and, therefore, influence the shape of the range distributions in the second implantation step. The experimental range profiles can be reproduced very well by atomistic computer simulations which take into account damage accumulation or dynamic annealing during a single implantation step as well as the influence of the defects formed by the preceding implantation steps.