Novel BF+ Implantation for High Performance Ge pMOSFETs

BF
⁺
implantation is used for the first time for the formation of source/drain (S/D) junctions in Ge MOSFETs. It offers a higher B activation level (~2.0 × 10
²⁰
cm
^-3
) and a shallower junction depth in Ge compared with B
⁺
and BF
₂
⁺
implantation for the same projected range, after rapid thermal annealing at 800°C. Germanium pMOSFETs using BF
⁺
implantation demonstrate a high ON/OFF ratio of ~10
⁷
and an enhancement of ON current, due to the reduction of S/D series resistance compared with B
⁺
or BF
₂
⁺
implanted junctions.