Ultra-Shallow P+/N Junction Formation in Si Using Low Temperature Solid Phase Epitaxy Assisted with Laser Activation

A combination of Ge pre-amorphization implantation (Ge-PAI), low-energy B implantation and laser annealing is a promising method to form highly-activated, abrupt and ultra-shallow junctions (USJ). In. our previous report of IIT 2006, we succeeded in forming pn junctions less than 10nm using non-melt double-pulsed green laser. However, a large leak-age current under reveme bias was observed consequently due to residual defects in the implanted layer. In this study, a method to form USJ is proposed: a combination of low-temperature solid phase epitaxy and non-melt laser irradiation for B activation. Ge pre-amorphization implantation was performed at energy of 6keV with a dose of 3x10(14)/cm(2). Then B implantation was performed at energy of 0.2keV with a dose of 1.2x10(15)/cm(2). Samples were annealed at 400 degrees C for 10h in nitrogen atmosphere. Subsequently, non-melt laser irradiation was performed at energy of 690mJ/cm(2) and pulse duration of 100ns with intervals of 300ns. As a result, USJ around 10nm with better crystallinity was successfully formed. And the leakage current of pn diodes was reduced significantly. Moreover, it is proven from secondary ion mass spectroscopy (SIMS) analysis that transient enhanced diffusion (TED) of B is specifically suppressed.