Avoiding preamorphization damage in MeV heavy ion-implanted silicon

Implantation of 1.0 MeV ‘isIn in Si results in secondary-defect formation during subsequent 900 “C annealing if the total number of displaced Si atoms is greater than 1.6~ lOi’/ cm’, achieved with a dose near 1.5 X 10i3/cm2. We demonstrate, though, that higher total In doses can be introduced without forming secondary defects by repetitive subthreshold implants each followed by an anneal to remove the implant damage. While a single 6 x 1013 In/ cm2 implant results in a high density of dislocation loops after annealing, instead using four separate 1.5 X 1013 In/cm” implants each followed by an anneal leads to the formation of only a few partial dislocations.