Optimisation of SIMOX structures formed by ion beam synthesis

Abstract

Recent experiments in producing SOI/SIMOX substrates have shown that near-ideal, planar structures with abrupt interfaces can be formed by annealing these materials at very high temperatures (typically >1300°C) and that excellent performance of CMOS circuits can be achieved if the silicon overlayer is restricted to a thickness of 1000 Å or less. In this article we describe experiments designed to evaluate the development of an optimum SIMOX structure by studying the effects of the implantation temperature and the annealing conditions on the microstructure produced during the synthesis process. For these experiments the oxygen ion dose chosen was 1.4 × 10 18 O +/cm 2 at 200 keV, where, theoretically, stoichiometric SiO 2 should only be formed at the peak of the implanted oxygen distribution. The analytical techniques used include: Rutherford backscattering (RBS), secondary ion mass spectroscopy (SIMS), cross-sectional transmission electron microscopy (XTEM), Raman spectroscopy and infrared absorption spectroscopy.