A semiconductor device includes a substrate and a semiconductor layer. The substrate includes a planar portion and a plurality of pillars on a periphery of the planar portion. The pillars are shaped as rectangular columns, and corners of two of the pillars at the same side of the planar portion are aligned in a horizontal direction or a direction perpendicular to the horizontal direction. The semiconductor layer is disposed over the planar portion and between the pillars.

A method for manufacturing a polysilicon SOI substrate including a cavity. The method includes: providing a silicon substrate including a sacrificial layer thereon; producing a first polysilicon layer on the sacrificial layer; depositing a structuring layer on the first polysilicon layer; introducing trenches through the structuring layer, the first polysilicon layer, and the sacrificial layer up to the silicon substrate; producing a cavity in the silicon substrate by etching, an etching medium being conducted thereto through the trenches; producing a second polysilicon layer on the first polysilicon layer, the trenches being thereby closed. A micromechanical device is also described.

A semiconductor device includes a substrate and a semiconductor layer. The substrate includes a planar portion and a plurality of pillars on a periphery of the planar portion. The pillars are shaped as rectangular columns, and corners of two of the pillars at the same side of the planar portion are aligned in a horizontal direction or a direction perpendicular to the horizontal direction. The semiconductor layer is disposed over the planar portion and between the pillars.

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.

Methods of forming semiconductor devices are provided. One of the methods includes following steps. A plurality of hard mask patterns is formed around a region of a substrate, wherein an imaginary connecting line is formed between corners of two of the plurality of hard mask patterns at the same side of the region, and the imaginary connecting line is substantially parallel to or perpendicular to a horizontal direction. A semiconductor layer is formed on the substrate by a selective epitaxial growth process.

A semiconductor device is provided. The semiconductor device includes a substrate, an oxide layer disposed over the substrate, and a first epitaxial layer disposed over the oxide layer. The first epitaxial layer has the first conductivity type. The semiconductor device also includes a second epitaxial layer disposed over the first epitaxial layer and a third epitaxial layer disposed over the second epitaxial layer. The second epitaxial layer has a second conductivity type that is opposite to the first conductivity type. The third epitaxial layer has the first conductivity type.

Methods of forming semiconductor devices are provided. One of the methods includes following steps. A plurality of hard mask patterns is formed around a region of a substrate, wherein an imaginary connecting line is formed between corners of two of the plurality of hard mask patterns at the same side of the region, and the imaginary connecting line is substantially parallel to or perpendicular to a horizontal direction. A semiconductor layer is formed on the substrate by a selective epitaxial growth process.

The present invention provides a semiconductor device, including a substrate, a first semiconductor layer, a plurality of first sub recess, a plurality of insulation structures and a first top semiconductor layer. The substrate has a first region disposed within an STI. The first semiconductor layer is disposed in the first region. The first sub recesses are disposed in the first semiconductor layer. The insulation structures are disposed on the first semiconductor layer. The first top semiconductor layer forms a plurality of fin structures, which are embedded in the first sub recesses, arranged alternatively with the insulation structures and protruding over the insulation structures.

A semiconductor device is provided. The semiconductor device includes a substrate, an oxide layer disposed over the substrate, and a first epitaxial layer disposed over the oxide layer. The first epitaxial layer has the first conductivity type. The semiconductor device also includes a second epitaxial layer disposed over the first epitaxial layer and a third epitaxial layer disposed over the second epitaxial layer. The second epitaxial layer has a second conductivity type that is opposite to the first conductivity type. The third epitaxial layer has the first conductivity type.

An integrated circuit may be formed by forming a buried isolation layer in an isolation recess in a single-crystal silicon-based substrate. Exposed lateral surfaces of the substrate at the buried isolation layer are covered with a dielectric sidewall. A seed trench is formed through the buried isolation layer to expose the substrate. A single-crystal silicon-based seed layer is formed through the seed trench, extending above the top surface of the buried isolation layer. A silicon-based non-crystalline layer is formed contacting the seed layer. A cap layer is formed over the non-crystalline layer. A radiant-induced recrystallization process converts the non-crystalline layer to a single-crystal layer aligned with the seed layer. The cap layer is removed and the single-crystal layer is planarized, leaving an isolated semiconductor layer over the buried isolation layer.