Mechanism of dopant activation enhancement in shallow junctions by hydrogen

The ability to activate greater amounts of dopants is a significant challenge for the realization of shallow junctions in device scaling for Si CMOS technology. Dopant activation is difficult to achieve in shallow junctions due to higher concentrations of dopants and possible formation of dopant clusters. The high temperatures currently used to activate dopants result in increased junction depth and process integration issues with high-k dielectrics. However, lowering the annealing temperature results in lesser dopant activation and problems with transient enhanced diffusion. Our previous work reported on the enhancement of activation in boron implanted at a dose of 5E14/cm² and annealed at temperatures of 450°C and below, by the incorporation of atomic hydrogen introduced by exposing the substrate to a hydrogen plasma at 250°C. In this work, further experiments have been carried out to get a better understanding of the mechanisms responsible for boron activation enhancement. Hydrogen-related activation was studied in boron, phosphorus and antimony implanted samples. The experimental results shed new light on the interactions among atomic hydrogen, point defects and dopants.