Study of end of range loop interactions with B+ Pmplant damage using a boron doped diffusion layer

A boron doped epilayer was used to investigate the interaction between end of range dislocation loops (formed from Gef implantation) and excess point defects generated from a low dose 1 X 10’4/cm2 Bf implant into silicon. The boron doping spike was grown in by chemical vapor deposition at a depth of 8000 A below the surface. The intrinsic diffusivity of the boron in the doped epilayer was determined by simply annealing the as-grown layer. The end of range (type II) dislocation loops were created using two overlapping room-temperature Gef implants of 75 and 190 keV each at a dose of 1 X 10’5/cm2. Upon annealing the amorphous layer regrew and a layer of type II dislocation loops formed -2300 A deep at a density of 8 X 10’“/cm2. The enhancement in the buried boron layer diffusivity due to the type II loop forming Ge+ implant was observed to increase approximately between 2.5 and 5 min from 1500X to a value 2500X above the intrinsic diffusivity before dropping back to intrinsic levels after 30 min at 800 “C. A low-energy (8 keV) 1 X 10t4/cm2 B+ (RP = 320 ii) implant into material without loops resulted in an average enhancement of 1540X in boron epilayer diffusivity after 2.5 min at 800 “C!. The enhancement dropped down to intrinsic diffusivity levels after 5 min at 800 “C. When a layer of loops was introduced and annealed prior to and deeper than a subsequent low-energy Bf implant, annealing of the B+ implant produced no measurable enhancement in the buried B layer diffusivity. Taken together this imples that the interaction kinetics between the dislocation loop layer and the damage induced interstitials are primarily diffu.sion limited and the loops are absorbing a significant fraction of the interstitials produced by the low-energy Bf implant. 0 I995 American Institute of Physics.