Precise secondary-ion mass spectrometry measurements were made of the depth profiles of 50 to 200keV 18O+ ions which had been implanted into Si and SiO2. A best fit of simulated profiles to observed ones was then obtained by using enough parameters in the power-law approximation to the stopping power. The observed, and best-fit, depth profiles were then compared with various computer simulations. The O depth distributions, for high-dose implantation, were determined by means of Rutherford back-scattering; followed by computer-simulated spectrum analysis. Computer methods were extended so as include sputter-erosion, the redistribution of implanted O, swelling effects, and compositional changes during implantation. The O profiles which were deduced from Rutherford back-scattering spectroscopic analyses were compared with those calculated by using the extended computer simulation. The analysis revealed that O atoms which were implanted at 550C migrated towards the surface before attaining stoichiometry (SiO2). The diffusion coefficient was estimated to be about 10-14cm2/s. This was some 2 orders of magnitude higher than the value for 16O in crystalline material at 550C. This was attributed to the induced dense defect distribution between the mean 16O depth and the surface.

T.Yoneda, K.Kajiyama, F.Tohjou, Y.Yoshioka, A.Ikeda, Y.Kisaka, T.Nishimura, Y.Kido: Japanese Journal of Applied Physics - 1, 1997, 36[12A], 7323-8

Table 190

Diffusivity of O in Si