A semiconductor device including a gate oxide of multiple thicknesses for
multiple transistors where the gate oxide thicknesses are altered through
the growth process of implanted oxygen ions into selected regions of a
substrate. The implanted oxygen ions accelerate the growth of the oxide
which also allow superior quality and reliability of the oxide layer,
where the quality is especially important, compared to inter-metal
dielectric layers. A technique has been used to vary the thickness of an
oxide layer grown on a silicon wafer during oxidation growth process by
implanting nitrogen into selected regions of the substrate, which the
nitrogen ions retard the growth of the silicon oxide resulting in a
diminished oxide quality. Therefore it is desirable to fabricate a
semiconductor device with multiple thicknesses of gate oxide by the
implanted oxygen ion technique.
