THE EFFECT OF DOSE-RATE ON INTERSTITIAL RELEASE FROM THE END-OF-RANGEIMPLANT DAMAGE REGION IN SILICON

Low temperature molecular beam epitaxy was used to grow boron doping s uperlattices DSLs in Si, with peak boron concentrations of 1 x 10(18)/ cm(3), and spike widths of 10 nm. Amorphization of these DSLs was achi eved using a series of Si+ implants of 30 and 112 keV, each at a dose of 1 x 10(15)/cm(2), which placed the amorphous to crystalline interfa ce between the first and second doping spikes. The dose rate of the Si + implants was varied from 0.13 to 1.13 mA/cm(2). Post-implantation an neals were performed in a rapid thermal annealing furnace at 800 degre es C, for times varying from 5 s to 3 min. Secondary ion mass spectrom etry was used to monitor the dopant diffusion after annealing. Increas ing the implant dose rate appears to increase the amount interstitial flux toward the surface but has no observable effect on the flux into the crystal. Transmission electron microscopy was used to study the en d of range defect evolution. Increasing dose rate was observed to decr ease the end of range defect density. These observations are consisten t with previous findings that indicate the amount of backflow toward t he surface decreases as the end of range loop density increases. (C) 1 997 American Institute of Physics.