Distribution of Hydrogen- and Vacancy-Related Donor and Acceptor States in Helium-Implanted and Plasma-Hydrogenated Float-Zone Silicon

Abstract

AbstractThe formation and evolution of hydrogen- and vacancy-related donor and acceptor states were studied in helium-implanted and subsequently hydrogen plasma-treated n-type Float-Zone (FZ) silicon wafers by means of two-point-probe Spreading Resistance (SR) measurements. He+-implantation was executed at 3.75 MeV and 11 MeV at fluences of 1×1014 cm−2. Post-implantation 13.56-MHz RF-plasma hydrogenations were carried out at 150 W either for 15 min or 1 hour, applying substrate temperatures between 350 °C and 500 °C. Enhanced donor concentrations as well as acceptor-like states were observed in the subsurface layers of the treated FZ Si samples after 15-min post-implantation H-plasma exposures. Under appropriate process conditions, the latter ones compensated for the n-type doping, so that even buried p-type layers were created. The experimental results indicated that oxygen played a central role in the formation of the acceptor-like states.