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 forming fins on a semiconductor device includes etching trenches into a monocrystalline substrate to form first fins and forming a first dielectric layer at bottoms of the trenches. Second fins of a material having a different composition than the substrate are grown on sidewalls of the trenches. A second dielectric layer is formed over the second fins. The first fins are removed by etching. The second fins are processed to form fin field effect transistor devices.

A method of fabricating a semiconductor device can include the following steps: (i) providing an initial sub-assembly including a trench-defining layer having a top surface; (ii) refining the initial sub-assembly into a first trench-cut intermediate sub-assembly by removing material to form an upper tier of a trench extending downward from the top surface of the trench-defining layer, the upper tier of the trench including two lateral trench surfaces and a bottom trench surface; and (iii) refining the first trench-cut intermediate sub-assembly into a second trench-cut intermediate sub-assembly by selectively removing material in a downwards direction starting from the bottom surface of the trench to form a lower tier of the trench, with the selective removal of material leaving at least a first defect blocking member in the lower tier of the trench.

A method for forming fins on a semiconductor device includes etching trenches into a monocrystalline substrate to form first fins and forming a first dielectric layer at bottoms of the trenches. Second fins of a material having a different composition than the substrate are grown on sidewalls of the trenches. A second dielectric layer is formed over the second fins. The first fins are removed by etching. The second fins are processed to form fin field effect transistor devices.

A method for making a semiconductor device may include forming buried spaced-apart insulator regions in a semiconductor substrate, and forming a monocrystalline semiconductor layer on the semiconductor substrate defining respective localized semiconductor on insulator (SOI) regions above the buried insulator regions, and respective localized bulk semiconductor regions laterally between adjacent SOI regions. The method may also include forming a superlattice in the monocrystalline semiconductor layer. The superlattice may include stacked groups of layers, with each group of layers including stacked base semiconductor monolayers defining a base semiconductor portion, and at least one non-semiconductor monolayer constrained within a crystal lattice of adjacent base semiconductor portions. The method may further include forming semiconductor devices in the monocrystalline layer, with some of the semiconductor devices in the localized SOI regions, and some other semiconductor devices in the localized bulk semiconductor regions.

A semiconductor device may include a semiconductor substrate, buried spaced-apart insulator regions in the substrate, and a monocrystalline semiconductor layer on the semiconductor substrate defining respective localized semiconductor on insulator (SOI) regions above the buried insulator regions, and respective localized bulk semiconductor regions laterally between adjacent SOI regions. The semiconductor device may also include a superlattice in the monocrystalline semiconductor layer. The superlattice may include stacked groups of layers, with each group of layers including stacked base semiconductor monolayers defining a base semiconductor portion, and at least one non-semiconductor monolayer constrained within a crystal lattice of adjacent base semiconductor portions. The semiconductor device may further include semiconductor devices in the monocrystalline layer, with at least some of the semiconductor devices in the localized SOI regions, and at least some other semiconductor devices in the localized bulk semiconductor regions.

A method of forming a semiconductor device includes forming a plurality of trenches extending into a semiconductor substrate from a first surface of the semiconductor substrate. Each of the trenches includes a narrower part in open communication with a wider part that is spaced apart from the first surface by the narrower part. The narrower part of adjacent trenches is laterally separated by a first region of the semiconductor substrate. The wider part of adjacent trenches is laterally separated by a second region of the semiconductor substrate that is narrower than the first region. The method further includes introducing an oxidizing agent into the wider part of the trenches through the narrower part of the trenches to oxidize the second region of the semiconductor substrate between adjacent trenches to form dielectric support structures that support the first region of the semiconductor.

A method is provided for fabricating a semiconductor structure. The method includes providing a bottom substrate having a first region and a second region, and forming a trench in the first region by patterning the bottom substrate. The method also includes forming an insulation layer in the trench in the first region, wherein the insulation layer exposes part of side surface of the trench, and forming a top substrate on the exposed side surface of the trench and the insulation layer. Further, the method includes forming a first fin portion in the first region, and forming a gate structure crossing the first fin portion, wherein the gate structure covers part of side and top surfaces of the first fin portion.

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.