The Influence of High Temperature Anneals on the Microstructure of Silicon on Insulator (SOI) Structures Formed by High-Dose Oxygen Implantation into Silicon

Buried oxide layers, for silicon on insulator (SOI) structures, have been formed by high-dose oxygen implantation into silicon. Float-zone (100) wafers were implanted in the dose range 0. 25 to 1.8x1018 0+/cm2 with 200 KeV 02 ions at 500 degrees C. The samples were subsequently annealed (furnace or incoherent lamp heater) in the range 1200 to 1405 degrees C, for up to 24 hours. Examination by TEM, SIMS & RBS showed that improvements in microstructure were brought about by either high-temperature anneals for typically 2 hours or a 1250 degrees C anneal for up to 24 hours. Furthermore by annealing at 1405 degrees C it is shown that a dose as low as 0.6x1018 0+/cm2 will form a continuous buried oxide layer below a good quality silicon layer.