In accordance with an embodiment of the present invention, a method of fabricating a semiconductor device includes forming openings partially filled with a sacrificial material, where the openings extend into a semiconductor substrate from a first side. A void region is formed in a central region of the openings. An epitaxial layer is formed over the first side of the semiconductor substrate and the openings, where the epitaxial layer covers the void region. From a second side of the semiconductor substrate opposite to the first side, the semiconductor substrate is thinned to expose the sacrificial material. The sacrificial material in the openings is removed and the epitaxial layer is exposed. A conductive material is deposited on the exposed surface of the epitaxial layer.

A method of fabricating a semiconductor device includes forming trenches filled with a sacrificial material. The trenches extend into a semiconductor substrate from a first side. An epitaxial layer is formed over the first side of the semiconductor substrate and the trenches. From a second side of the semiconductor substrate opposite to the first side, the sacrificial material in the trenches is removed. The trenches are filled with a conductive material.

A semiconductor structure and a method for forming a semiconductor structure are provided. The method includes receiving a semiconductor substrate having a first region and a second region; forming a dielectric layer over the semiconductor substrate; removing portions of the dielectric layer to form a dielectric structure in the first region, wherein the dielectric structure includes a base structure and a plurality of first isolation structures over the base structure; forming a semiconductor layer covering the first region and the second region; removing a portion of the semiconductor layer to expose a top surface of the plurality of first isolation structures; and forming a plurality of second isolation structures in the second region.

An integrated circuit may be formed by forming an isolation recess in a single-crystal silicon-based substrate. Sidewall insulators are formed on sidewalls of the isolation recess. Thermal oxide is formed at a bottom surface of the isolation recess to provide a buried isolation layer, which does not extend up the sidewall insulators. A single-crystal silicon-based semiconductor layer is formed over the buried isolation layer and planarized to be substantially coplanar with the substrate adjacent to the isolation recess, thus forming an isolated semiconductor layer over the buried isolation layer. The isolated semiconductor layer is laterally separated from the substrate.

A method of fabricating a semiconductor device includes forming trenches filled with a sacrificial material. The trenches extend into a semiconductor substrate from a first side. An epitaxial layer is formed over the first side of the semiconductor substrate and the trenches. From a second side of the semiconductor substrate opposite to the first side, the sacrificial material in the trenches is removed. The trenches are filled with a conductive material.

A method for fabricating a semiconductor device includes forming an opening in a first epitaxial lateral overgrowth region to expose a surface of the semiconductor substrate within the opening. The method further includes forming an insulation region at the exposed surface of the semiconductor substrate within the opening and filling the opening with a second semiconductor material to form a second epitaxial lateral overgrowth region using a lateral epitaxial growth process.

An integrated circuit may be formed by forming an isolation recess in a single-crystal silicon-based substrate. Sidewall insulators are formed on sidewalls of the isolation recess. Thermal oxide is formed at a bottom surface of the isolation recess to provide a buried isolation layer, which does not extend up the sidewall insulators. A single-crystal silicon-based semiconductor layer is formed over the buried isolation layer and planarized to be substantially coplanar with the substrate adjacent to the isolation recess, thus forming an isolated semiconductor layer over the buried isolation layer. The isolated semiconductor layer is laterally separated from the substrate.

A method of making a dual isolation fin comprises applying a mask to a substrate and etching the exposed areas of the substrate to form a mandrel; forming a dielectric layer on the surface of the substrate and adjacent to the mandrel; forming a first epitaxially formed material on the exposed portions of the mandrel; forming a second epitaxially formed material on the first epitaxially formed material; forming a first isolation layer on the dielectric layer and adjacent to the second epitaxially formed material; removing the mask and mandrel after forming the first isolation layer; removing the first epitaxially formed material after removing the mask and mandrel; and forming a second isolation layer.

A method of making a dual isolation fin comprises applying a mask to a substrate and etching the exposed areas of the substrate to form a mandrel; forming a dielectric layer on the surface of the substrate and adjacent to the mandrel; forming a first epitaxially formed material on the exposed portions of the mandrel; forming a second epitaxially formed material on the first epitaxially formed material; forming a first isolation layer on the dielectric layer and adjacent to the second epitaxially formed material; removing the mask and mandrel after forming the first isolation layer; removing the first epitaxially formed material after removing the mask and mandrel; and forming a second isolation layer.

A method of making a dual isolation fin comprises applying a mask to a substrate and etching the exposed areas of the substrate to form a mandrel; forming a dielectric layer on the surface of the substrate and adjacent to the mandrel; forming a first epitaxially formed material on the exposed portions of the mandrel; forming a second epitaxially formed material on the first epitaxially formed material; forming a first isolation layer on the dielectric layer and adjacent to the second epitaxially formed material; removing the mask and mandrel after forming the first isolation layer; removing the first epitaxially formed material after removing the mask and mandrel; and forming a second isolation layer.