Formation of extremely shallow junctions for sub-90 nm devices

The productivity advantage of pulsed plasma implantation versus traditional beamline-based implantation has long been its primary attraction. To assess the technical potential of plasma-based implant for semiconductors, we will compare pulsed plasma with beamline implantation based on performance for shallow junction scaling. Three factors are used to evaluate shallow junction scaling: (1) control of the as-implanted and annealed junction depth, (2) extensibility to extremely shallow junctions, and (3) dose control. Dopant depth profiles are used to show superior control over junction depth, equivalent dose control and shallower junctions for pulsed plasma implantation. ta presented demonstrate that pulsed plasma implantation can provide better low energy scaling of dopant profile depth versus traditional beamline implantation, enabling extremely shallow junctions to be formed. It is also shown that the dose control and retention are equivalent with beamline implant, and the combination of shallow scaling and dose control permit improved junction characteristics as illustrated by sheet resistance versus junction depth plots. The critical dose control requirements of semiconductor implantation clearly differentiate between the pulsed plasma approach and continuous plasma (immersion type) systems. The pulsed approach demonstrates effective closed loop control while recently published results for continuous plasma do not. Finally, results published over the last several years highlight significant advantages in device performance for plasma-based implant versus beamline implant.