Problems in the analysis of semiconductor device materials exposed to ionizing radiation

Enhanced diffusion of impurities in solids at elevated temperatures under exposure to high-energy particles is well known and is largely attributable to the generation of excess vacancies. This paper deals with the morn subtle effects that can be caused by ionizing radiation (below the threshold for atomic displacements) and can occur even at or below room temperature. In recent years, enhancement of diffusion under the action of ionizing radiation has been observed both in insulators and in semiconductors of the diamond lattice type. It has become evident that analytical results obtained by techniques using strongly ionizing radiation (for instance, electron or ion microprobes), or obtained on samples exposed to ionizing radiaticm beforehand (as in neutron activation work) can be very misleading if the possible alteration of the diffusion profile by the ionizing radiation is not taken into account. Another source of error in neutron activation work is the transfer of impurities from the container material itself to the sample surface, followed by radiation enhanced diffusion into the sample. An attempt is made to give a brief survey of the enhancement effects due to ionizing radiation reported in the literature so far, as well as of the explanations proposed for these effects. Some recent work by the authors is also included.