FORMATION OF SILICON-NITRIDE LAYERS BY NITROGEN IMPLANTATION INTO SI/COSI2 SYSTEMS

The high dose implantation of nitrogen through silicide layers into the silicon substrate allows the electrical separation of the silicide from the substrate by the formation of an insulating nitride layer. The influence of the radiation enhanced diffusion on the formation of the nitride layer and the quality of the silicide layer has been investigated by a series of implantations at different ion current densities, but at a constant target temperature. The experimental results prove an increase of both, the nitrogen and the metal redistribution by secondary implantation processes with increasing ion current densities. By comparing the measured concentration profiles with the primary ion distribution obtained by computer simulation the radiation enhanced diffusion of the components is discussed and an improved technique of nitride formation by double implantation is presented.