Method for forming isolated semiconductor structures

Abstract

A number of dielectrically isolated single crystal islands are formed by implanting neon or other group Zero ions into a semiconductor substrate, preferably silicon, at a sufficiently high energy to created an amorphized region in the interior of the substrate, without excessively damaging the substrate surface through which the ions pass. The amorphized regions are highly resistive, and are suitable for isolation in some applications. Where better isolation is desired, a dielectric isolation structure is formed as follows. Trenches are formed down into the amorphized regions, and the substrate is heavily oxidized to convert the amorphized regions into buried oxide regions and the island sidewalls into oxide. The islands are made thicker by removing the oxide from the islands' top surfaces and sidewalls, and growing epitaxial silicon over the substrate. Second trenches are formed down to the buried oxide regions, and the substrate is again oxidized to convert the islands' sidewalls to oxide. The remaining open space of the second trenches is filled, and devices of any desired type are formed in the single crystal islands.