Solid phase epitaxy and regrowth process with controlled defect density profiling for heteroepitaxial semiconductor on insulator composite substrates

A method of fabricating a plurality of FET devices on a composite substrate which includes forming source, drain, and gate regions in said substrate and making electrical contact thereto, the formation of said composite substrate being comprised of the steps of:

• (a) forming a crystal layer of a semiconductor material on a substrate of an insulator material;
• (b) implanting a given ion species into said semiconductor crystal layer under such conditions that the implanted ions penetrating through said semiconductor crystal layer and into said insulator substrate, at their respective residual energies, are insufficient to significantly damage said insulator substrate such that substrate-originated contaminants are released into said semiconductor layer, a sufficient density of said implanted ions being implanted into said semiconductor crystal layer so as to amorphize a buried layer of said semiconductor crystal layer;
• and
• (c) annealing said semiconductor material at a given temperature so as to recrystallize said buried layer, said given temperature being appropriate for the remaining portion of said semiconductor crystal layer to act as the primary nucleation seed for the recrystallization of said buried amorphous layer.

A method of fabricating a silicon-on-sapphire composite substrate suitable for use in the further fabrication of high-speed integrated circuits, the method comprising the steps of:

• (a) forming a crystal silicon layer of a given thickness on the surface of a sapphire substrate;
• (b) implanting a given dose of silicon ions, at a given energy, into said crystal silicon layer so as to amorphize a buried layer of said crystal silicon layer, the number of said silicon ions passing through said crystal silicon layer and into said sapphire substrate, at their respective residual energies, being insufficient to damage said sapphire substrate such that significant quantities of aluminum out-diffuse from said insulator substrate and into said buried amorphous silicon layer and the remaining portion of said crystal silicon layer;
• and
• (c) regrowing said buried amorphous silicon layer to form a buried recrystallized silicon layer, the remaining portion of said crystal silicon layer acting as the regrowth nucleation seed for said buried amorphous layer such that said buried recrystallized silicon layer has a common crystallographic orientation and, further, is substantially free of crystal lattice defects.