MECHANISM OF SI ISLAND RETENTION IN BURIED SIO2 LAYERS FORMED BY OXYGEN-ION IMPLANTATION

The density of silicon Islands capped in buried SiO2 layers produced b y the implantation of oxygen into (001)Si substrates is monitored by a tomic force microscopy for the oxygen dose range just above that requi red for continuous oxide formation. In addition to an exponential incr ease in the Si island density with oxygen dose, the regularly shaped r emnants of an SiO-(2) phase with a reduced HF etch rate were found. Th e formation of this additional oxide phase as a result of enhanced int ernal pressure inside the Si crystal is proposed to account for the re tention of Si islands in the buried oxide. (C) 1997 American Institute of Physics.