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 110 18 /cm 3 , 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 10 15 /cm 2 , 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/cm 2. 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.

Mechanisms of Focused Ion Beam Implantation Damage and Recovery in Si

“…The annealing conditions were designed to cause known defect transformations that are known to occur in conventional (broad area implantation) samples. [20][21][22][23][24] We expect that the defect types are similar for the FIB-implanted specimens in this work, as we are comparing similar implanted doses of ions and annealing temperatures and time.…”

Interactions of Moving Dislocations in Semiconductors with Point, Line and Planar Defects

“…We believe that this is related to the known dependence of end-of-range dislocation loop densities upon implant fluxes. This modifies the flux of Si point defects or implant species from the implanted region, as these loops serve to trap diffusing species [34].…”

The effect of preamorphization energy on ultrashallow junction formation following ultrahigh-temperature annealing of ion-implanted silicon

“…It was shown that the interstitial flux from the EOR damage is approximately an order of magnitude greater into the substrate than toward the surface for overlapping 112-keV and 30-keV Si + implants to 1 ϫ 10 15 cm 2 performed at ͑20± 1͒°C. 32 The decrease in the interstitial flux toward the surface was attributed to the EOR damage acting as interstitial traps, which prevent a significant fraction of the interstitials from diffusing toward the substrate surface. Jones et al correlated the EOR dislocation loop density with the amount of interstitial backflow toward the surface, which increased with decreasing implant temperature ͑presumably due to the fact that less EOR damage is available to prevent the interstitials from diffusing toward the substrate surface͒.…”