The impact of helium co-implantation on hydrogen induced donor profiles in float zone silicon

Doping profiles in proton and helium co-implanted and annealed n-type float zone silicon wafers are analyzed by means of spreading resistance measurements. After annealing at sufficiently high temperatures and/or long-enough duration, the hydrogen-related donor profiles known from proton implantations are significantly enhanced by the helium irradiation. The resulting profile shape exhibits a strong resemblance to the radiation damage distribution of the co-implantation. By increasing the ultimately introduced num-ber of hydrogen related donors without varying the available amount of hydrogen, it is shown that the donor profile resulting from proton implantation and annealing is limited by the defect species and the implanted hydrogen is supplied in surplus. The maximum of the additionally induced donor distribution by the he-lium implantation shows a different dependency on the fluence compared to the donor maximum induced by mere proton irradia-tion. The diffusion of protons through the irradiated layer during annealing is impacted by the He-irradiation.