Ion Implantation Damage and B Diffusion in Low Energy B Implantation with Ge Preimplantation

Abstract

For low energy B (LEB) implantation into Si, the channeling tail is larger than for BF2⁺ implantation, so Ge⁺ preamorphization is expected to provide a shallower junction. We studied the Ge⁺ and B⁺ implantation damages and the damage-induced B diffusion. The substrate implanted Ge⁺ with 2×l0¹⁴ cm^-2, that is, a complete amorphization, retains less residual defects after RTA. However the sheet resistivity (S) is higher than the sample implanted with only LEB. Solid phase epitaxy (SPE) of amorphized layer causes B out-diffusion. The diffusion length of the amorphized substrate is smaller than that of LEB. We expect that the B diffusion is enhanced by the LEB damage, which corresponds to the enhanced diffusion of light damage.