Analysis of disorder distributions in boron implanted silicon

Channeling effects on the yield of large angle backscattered energetic H+ or He+ were used to investigate properties of the disorder in Si samples previously implanted with B11 ions at substrate temperatures of -150°C to -50°C. Exposure of the implanted samples to the analyzing beam at room temperature caused a large reduction in the amount of disorder measured. A successive layer removal technique by anodic oxidation and stripping was used to obtain a depth scale for 1.8 MeVHe+ analyses of lightly disordered samples. The results of additional experiments indicate that for 1 MeV He+ in Si the aligned stopping power is about 80 per cent of the random stopping power. Measured and calculated values of the minimum yield X R for the substrate underlying amorphous layers suggested a plural scattering treatment of dechanneling of the analyzing beam using previously measured values of the critical angle. The scattering center distributions calculated from this treatment of dechanneling are presented for 450 keV H+ analyses of implants with doses of 1 × 1014 -1.6 × 1015 200 keV B ions/cm2. The distribution calculated from the plural scattering dechanneling approximation is compared with distributions calculated from other treatments for a 1.8 MeV He+ analysis of a 5 × 1014 200 keV B ions/cm2 implant. The plural scattering treatment works fairly well for 200 keV implantations at doses < 8 × 1014 ions/cm2.