Since the invention of the transistor at Bell Laboratories in the United States in 1947, almost all areas of our life have been touched by microelectronics, where silicon plays a dominant role as a basic material. Indeed, a continuous trend towards smaller but more powerful devices has been evidenced. Nonetheless, this miniaturization has been limited by difficulties in semiconductor device fabrication, further hampered by physical limits. Among dopants, B is absolutely the most used impurity to create p-type doped regions in silicon. Unfortunately the interaction with defects generated during the common industrial steps for devices production makes B to strongly diffuse and precipitate, hindering its use for ultra-shallow junction creation. Hence, new studies are required to face the problem. We deeply investigated the interaction of high B doped regions with the excess of defects generated by ion implantation and thermal annealing, as far as B precipitation, i.e. electical deactivation, and diffusion are concerned. The found results are hence used to develop new methodologies in order to control these two phenomena, by appropriate defect engineering.