Epitaxial growth of silicon on oxygen implanted substrates

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.
Conditions for epitaxial growth from a silane source in a
reactor, built and commissioned as a part of the programme,
have been established.
Buried implanted oxide layers have been formed by high dose
implantation of oxygen ions in silicon. The effects of
dose at a given energy, energy for a given peak concentration,
and temperature on the distribution profile of oxygen have
been studied. An approximate Gaussian distribution is
observed at doses contributing less than the stoichiometric
requirement of oxygen for the formation of silicon dioxide.
A saturation in the oxygen content 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 0+.cm-2 at 200 keY which provides the stoichiometric concentration only at the peak of the distribution.
The epitaxial layers deposited on substrates maintained at
5500C 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. The minority carrier lifetime is
comparable to that in diodes processed similarly but without
an implanted oxide layer.