Characterization of boron and phosphorus surface contamination in high current ion implantation

Both implant equipment vendors and semiconductor manufacturers expend significant resources to reduce cross-species surface contamination. Equipment vendors continually refine their implanter designs to this end, while chipmakers may utilize in situ processes to sputter-clean beamline and process chamber surfaces during a dopant species change. This paper investigates the effectiveness of ion beam sputter processes to reduce boron and phosphorus cross-contamination. Results are compared for as-implanted wafers, and wafers that receive a post-implant plasma ash and wet clean. Additionally, device wafers are processed with varying levels of surface contamination at source-drain extension implant in order to evaluate the effects on transistor parameters.