The role of point defect sources in the formation of boron polyemitters

Optimization of steepness and penetration depths of boron emitter profiles is the key for realization of p-n-p transistors of high performance and speed. Therefore, we investigated boron-polyemitter diffusion. We found penetration depths varying by as much as 50%, depending on the details of the polyemitter processing sequence. We prove that the observed variation in boron emitter profiles is not simply dependent on the morphology of the interfacial oxides. Rather, we obtained evidence that the generation of excess point defects during polyemitter processing, which translates into enhanced diffusion of boron in monosilicon, is the dominating factor. This paper reports for the first time on a set of experiments designed to identify the point defect generating mechanisms and to assess their contribution to enhanced boron emitter diffusion.<>