The effect of dose rate on interstitial release from the end-of-range implant damage region in silicon

Abstract

Low temperature molecular beam epitaxy was used to grow boron doping superlattices DSLs in Si, with peak boron concentrations of 1×1018/cm3, and spike widths of 10 nm. Amorphization of these DSLs was achieved using a series of Si + implants of 30 and 112 keV, each at a dose of 1×1015/cm2, which placed the amorphous to crystalline interface between the first and second doping spikes. The dose rate of the Si + implants was varied from 0.13 to 1.13 mA/cm2. Post-implantation anneals were performed in a rapid thermal annealing furnace at 800 °C, for times varying from 5 s to 3 min. Secondary ion mass spectrometry was used to monitor the dopant diffusion after annealing. Increasing 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 end of range defect evolution. Increasing dose rate was observed to decrease the end of range defect density. These observations are consistent with previous findings that indicate the amount of backflow toward the surface decreases as the end of range loop density increases.