New Approaches to Ultra Shallow Junction Formation by Molecular Implantation and Millisecond Laser Spike Annealing

Scaling of source/drain extension junctions continues to be a major focus for sub 45 nm planar CMOS process development. Device scalability, drive current, and leakage performance are determined by junction depth, activation, and residual disorder. These requirements have driven ion implants into the deep sub-keV regime and integration of millisecond anneals for activation. In this paper, we introduce the formation of extension junctions using thermally stable boron containing molecular implant which alleviates productivity concerns with sub-keV implantation and runs on a standard high current implanter. In combination with advanced millisecond sub-melt laser anneal, p-n junctions with high activation and negligible dopant profile movement are produced. Limiting diffusion and maximizing activation with optimized dopant concentration, effect of different amorphization schemes, and the use of diffusion modifiers such as carbon will also be discussed in the context of millisecond laser anneals. In addition, the role of implantation in minimizing residual disorder after laser anneals and its relevance to junction leakage is discussed.