N-type doping of silicon by proton implantation

Ion implantation is one of the most common processes in semiconductor manufacturing. Unfortunately the implantation depth and is limited due to the mass of phosphorous or arsenic. Proton irradiation can go beyond this limit and be utilized to adjust the doping of silicon power devices even in a high depth. The creation of donors is studied for high energy, high dose proton irradiation (2 MeV, fluences 10¹⁴ to 10¹⁶ cm^-2) in FZ-silicon. The relation between the proton implantation dose and the resulting doping is determined and is compared with previous results. A saturation effect related to the oxygen content is found and an experimental evidence for the incorporation of oxygen in hydrogen-related shallow thermal donors (STD(H)) is given. The resulting profiles are studied with Spreading-Resistance-Profiling and their complex shape is with the help of SRIM calculations [10]. Acceptors and donors are created. The superposition of both profiles explains the experimental results.