Mechanism Of Electron-Beam Doping In Semiconductors

A mechanism of electron-beam doping (EBD) was investigated. A semiconductor surface was covered by an overlayer of impurity sheet and the overlayer surface was irradiated with high-energy electrons. Interstitials of displaced atoms in the overlayer, which were introduced by irradiation, migrated to the surface or the interface of the semiconductor. These strongly diffused at the surface with a very large surface diffusivity of the order of 10(-5) cm(2) sec(-1) and also had a volume diffusivity of the order of 10(-15) cm(2) sec(-1). High impurity concentrations in the surface layer during irradiation were found to be on the order of the concentration of the matrix atoms. The three main points noted in EBD were the following: (i) there was room-temperature diffusion, (ii) surface diffusion played an important role, and (iii) enhanced diffusions, due to the kick-out mechanism and recombination, occurred.