Silicon-on-insulator structures using high dose oxygen implantation to form buried oxide films

The feasibility of growing epitaxial layers of silicon on silicon substrates with a buried oxide layer formed by the implantation of oxygen ions, has been studied. Buried implanted oxide layers have been formed by high dose implantation of oxygen ions in silicon. The effect of dose at a given energy for a given peak concentration on the distribution profile of oxygen has been studied. An approximately Gaussian distribution is observed at doses contributing less than the stoichiometric requirement of oxygen for the formation of silicon dioxide. A saturation in the peak oxygen concentration is reached when the stoichiometric requirement is exceeded. A consequent reduction in the interface damage is also observed. Other parameters being equal, at higher substrate temperatures the interface damage is decreased. It has been attempted to optimise conditions for a dose of 1.4 x 1018 cm-2 at 200 keV which provided the stoichiometric concentration only at the peak of the distribution. The epitaxial layers deposited on substrates maintained at approx. 550 deg C during implantation have a crystalline quality comparable to those of layers on untreated substrates. Fabricated p-n junction diodes have low leakage currents and high breakdown voltages. (author)