The out-diffusion of these elements from bare wafers at 1200C, and especially its dependence upon the annealing atmosphere, was studied by using spreading resistance and secondary ion mass spectroscopic methods. It was found that B out-diffusion occurred when the sample was annealed in H, but was completely suppressed in Ar; even when the dopant concentration was as high as 3 x 1018/cm3 and the annealing time was as long as 2h. No marked dependence upon the type of atmosphere was observed in the case of the other impurities, and this was attributed to the desorption of B atoms from the surface.

Outdiffusion of Impurity Atoms from Silicon Crystals and its Dependence upon the Annealing Atmosphere. L.Zhong, Y.Kirino, Y.Matsushita, Y.Aiba, K.Hayashi, R.Takeda, H.Shirai, H.Saito, J.Matsushita, J.Yoshikawa: Applied Physics Letters, 1996, 68[9], 1229-31