The damage recovery and electrical activation of shallow boron implants in silicon: The effects of high energy implants

A study of the interaction between shallow implanted boron junctions and high-energy silicon implants is presented. The implantation induced damage structure and its evolution with annealing temperature was followed by transmission electron microscopy, The electrically active boron depth profiles have been measured using spreading resistance profiling. The results show that the boron secondary defect formation is greatly suppressed by a high-energy silicon implant. A reduction by more than 50% has been observed. Moreover, the electrical activation is affected, and is found to be very sensitive to the initial damage structure, which depends on the implant conditions and subsequent thermal processes. The interaction between the damage structure of the low energy and high energy implants has been simulated by solving the appropriate set of fully coupled diffusion equations for interaction and diffusion of point defects. A comparison of the experimental findings with the results of the simulations is presented and discussed.