ELECTRON-BEAM DOPING BY SUPERDIFFUSION IN UNIRRADIATED REGIONS (X-LESS-THAN-300-ANGSTROM) OF SEMICONDUCTORS AT ROOM-TEMPERATURE

Electron beam doping processes in the damageless region and at room te mperature mere investigated before annealing. In the three-layer syste m of layer 3/layer 2/layer I: the impurity sheet (layer 2) was sandwic hed between two semiconductor wafers. The surface of layer 3 was irrad iated with electron beams of 750keV and 7MeV. Interstitials of displac ed atoms in the overlayer, which were introduced by irradiation, migra ted to the surface of the semiconductors. These interstitials diffused rapidly at the surface with a very large surface diffusivity of simil ar to 10(-5) cm(2).s(-1). The diffusion process was observed using an atomic force microscope (AFM). Impurity concentrations in the surface layer during irradiation were found to be on the order of matrix atom concentration. Electron irradiation produced a number of self-intersti tials that migrated with large surface diffusivities at the surface. D iffusion was enhanced due to the kick-out mechanism at the interface o f the system and in the depth direction of the semiconductors.