Non-melt laser annealing of Plasma Implanted Boron for ultra shallow junctions in Silicon

Abstract

In this work we present results on sub-melt Excimer laser annealing in order to obtain difussionless activation of Boron for the creation of ultra shallow P-MOS devices. For the fulfillment of the strict requirements imposed by the ITRS roadmap for the 32 nm node we have implemented two emerging techniques: non-melt laser annealing and BF 3 Plasma Doping implantation (PLAD). By using PLAD, we were able to create ultra shallow and abrupt as implanted profiles. On the other hand, by performing laser annealing on the samples in the sub-melt regime, we can achieve high levels of electrical activation, while practically eliminating Boron diffusion, due to its capability to deliver low thermal budget in the sub-microsecond time scale. An Excimer KrF laser ( λ = 248 nm and pulse duration 38 ns) has been used. The post annealing characterization of the samples included SIMS and Van Der Pauw Sheet resistance measurements. SIMS data indicate almost difussionless dopant behavior with R s values at 680 Ω/sq. We have concluded our analysis with the examination of the morphological characteristics both of the surface of the sample using Atomic Force Microscopy (AFM) and the evolution of the recrystallization of the amorphized layers and the removal of the defects by means of cross-section Transmission Electron Microscopy.