RUTHERFORD BACKSCATTERING AND CHANNELING STUDIES OF BURIED NITRIDE STRUCTURES DIRECTLY PRODUCED BY HIGH-INTENSITY ION-IMPLANTATION OF NITROGEN INTO SILICON

Recent work on buried nitride structures has shown that by implanting nitrogen in silicon at sufficiently high beam current densities, or in other words by using the so-called High Intensity Ion Implantation (H III), it is possible to produce directly stoichiometric layers of Si3N 4. Under appropriate conditions of flux, dose and temperature, the HII I of nitrogen appears to have similarities to oxygen implantation in t hat the composition at the peak of the implant profile saturates at th e stoichiometric ratio for Si3N4 while maintaining good crystalline qu ality in the silicon overlayer. This is a technologically important is sue which may warrant a reconsideration of the standard technology wit h a view to obtaining device-worthy silicon-on-insulator substrates. B uried nitride structures have been directly formed by high energy (1 M eV mol-1) HIII of molecular nitrogen in heat sunk (111) silicon substr ates at doses ranging from 7x10(17) to 2.1x10(18) CM-2 and temperature s up to 300-degrees-C. Rutherford backscattering and channelling analy sis of the as-implanted samples was undertaken to evaluate the distrib utions of the implanted nitrogen atoms and the extent of radiation dam age in the silicon overlayers. It has been found that the resulting st ructures depend strongly on the dose rate, implant dose, temperature a nd manner of beam heating. The individual role as well as the combined effect of the above implantation parameters on the degree of near-sur face crystallinity, nitrogen distribution, critical dose for direct fo rmation of a Si3N4 layer and upper interface region have been studied and a basis for further optimization has been outlined.