Method of fabricating semiconductor devices with isolated superlattice structures

A method for making a semiconductor device comprising:

• implanting non-semiconductor atoms into a localized region of a semiconductor layer;
• forming a superlattice on the semiconductor layer over the localized region, the superlattice comprising a plurality of stacked groups of layers and extending laterally outward from the localized region, each group of layers comprising a plurality of stacked base semiconductor monolayers defining a base semiconductor portion, and at least one monolayer of the non-semiconductor atoms constrained within a crystal lattice of adjacent base semiconductor portions;
• performing a thermal treatment to cause non-semiconductor atoms from the superlattice to be displaced, and to cause non-semiconductor atoms from the localized region to migrate into the superlattice and replace at least some of the displaced non-semiconductor atoms;
• and
• forming a first device overlying the superlattice and a second device overlying an adjacent portion of the semiconductor layer after performing the thermal treatment.

A method for making a semiconductor device comprising:

• implanting oxygen atoms into a localized region of a semiconductor layer;
• forming a superlattice on the semiconductor layer over the localized region, the superlattice comprising a plurality of stacked groups of layers, each group of layers comprising a plurality of stacked base silicon monolayers defining a base silicon portion, and at least one monolayer of oxygen atoms constrained within a crystal lattice of adjacent base silicon portions;
• and
• performing a thermal treatment to cause oxygen atoms from the superlattice to be displaced, and to cause oxygen atoms from the localized region to migrate into the superlattice and replace at least some of the displaced oxygen atoms.