DIRECT FORMATION OF DEVICE WORTHY THIN-FILM SIMOX STRUCTURES BY LOW-ENERGY OXYGEN IMPLANTATION

Thin film SOI/SIMOX samples suitable for fully depleted CMOS circuits have been directly prepared by low energy oxygen ion implantation. In this paper we report the successful optimisation of the processing par ameters, including energy, dose and wafer temperature to form low defe ct density, device worthy substrates with both the silicon overlayer a nd the buried oxide layer thicknesses in the range of 700-1400 angstro m. Samples implanted at 70 or 90 keV with doses in the range of 3 x 10 (17) to 6 x 10(17) O+/cm2 have been investigated. The wafers were preh eated and implanted at temperatures in the range of 500 up to 680-degr ees-C using halogen lamps to provide background heating. The samples w ere annealed for 6 h in either nitrogen ambient at 1320-degrees-C or i n argon + 0.5% O2 at a temperature of 1300-degrees-C and then analyzed using XTEM, SIMS and RBS/channelling analysis. Results indicate a con tinuous buried layer of SiO2, planar interfaces and a drop of more tha n three orders of magnitude in the defect density from 10(8) down to l ess than 10(5)/cm2 in samples implanted under optimum conditions of 70 keV, 3.3 x 10(17) O/cm2, and implantation temperature (T(i)) of 680-d egrees-C.