The As was implanted into thermally grown material, at energies of between 40 and 70keV, to a dose of 1015/cm2 and was diffused, under ambients of O2 or N2, at temperatures of between 1000 and 1100C. The As profiles, as determined by using secondary ion mass spectrometry, revealed the occurrence of retarded diffusion in the high-concentration region (above 1019/cm3), for both ambients. It was found that, after annealing under N2, diffusion in the low-concentration region (below 1019/cm3) was greatly enhanced in the early stages of annealing and decreased markedly with annealing time. This time-dependent diffusion depended upon the implantation energy and the annealing temperature. The As diffusivities were extracted by numerically fitting calculated profiles to secondary ion mass spectrometry data. The activation energy for diffusion was estimated to be 3.5eV. The time-dependent diffusion was attributed to the migration of interstitial As and to its reaction with the SiO2 network.

Time-Dependent Diffusion of Ion-Implanted Arsenic in Thermally Grown SiO2. T.Yamaji, F.Ichikawa: Journal of Applied Physics, 1988, 64[5], 2365-71