A method includes forming a stacked structure of a plurality of first semiconductor layers and a plurality of second semiconductor layers alternately stacked in a first direction over a substrate, the first semiconductor layers being thicker than the second semiconductor layers. The method also includes patterning the stacked structure into a first fin structure and a second fin structure extending along a second direction substantially perpendicular to the first direction. The method further includes removing the first semiconductor layers of the first fin structure to form a plurality of nanowires. Each of the nanowires has a first height, there is a distance between two adjacent nanowires along the vertical direction, and the distance is greater than the first height. The method includes forming a first gate structure between the second semiconductor layers of the first fin structure.

According to one embodiment, a method for manufacturing a semiconductor device is disclosed. The method can include forming a second layer covering a first layer on a first region of a semiconductor substrate. The semiconductor substrate includes the first region and a second region. The first layer covers the second region and a portion of the first region. First openings are formed. The method can include removing the first layer on the second region using the second layer as a mask. The method can include forming an impurity region including an n-type impurity in the second region. The method can include removing the second layer, and growing silicon layers inside the first openings and on the second region. In addition, the method can include polishing a portion of each of the silicon layers using the first layer as a stopper.

A semiconductor device has a semiconductor layer and a substrate. The semiconductor layer constitutes at least a part of a current path, and is made of silicon carbide. The substrate has a first surface supporting the semiconductor layer, and a second surface opposite to the first surface. Further, the substrate is made of silicon carbide having a 4H type single-crystal structure. Further, the substrate has a physical property in which a ratio of a peak strength in a wavelength of around 500 nm to a peak strength in a wavelength of around 390 nm is 0.1 or smaller in photoluminescence measurement. In this way, the semiconductor device is obtained to have a low on-resistance.

A semiconductor stack includes a substrate made of silicon carbide, and an epi layer disposed on the substrate and made of silicon carbide. An epi principal surface, which is a principal surface opposite to the substrate, of the epi layer is a carbon surface having an off angle of 4 or smaller relative to a c-plane. In the epi principal surface, a plurality of first recessed portions having a rectangular circumferential shape in a planar view is formed. Density of a second recessed portion that is formed in the first recessed portions and is a recessed portion deeper than the first recessed portions is lower than or equal to 10 cm.sup.2 in the epi principal surface.

A method for manufacturing a silicon carbide substrate includes steps of preparing a silicon carbide substrate having a main surface, polishing the main surface of the silicon carbide substrate using a polishing agent containing a metal catalyst, and cleaning the silicon carbide substrate after the step of polishing. The step of cleaning includes a step of cleaning the silicon carbide substrate with aqua regia.

A field-effect transistor (FET) and method of manufacture thereof include patterning a mask above a source and drain of a FET to form holes in the mask, growing epitaxial structures from the holes in the mask, and growing a doped epitaxial shell to coat sidewalls of the epitaxial structures.

A device includes a substrate, a stacked structure and a first gate stack. The stacked structure includes a plurality of first semiconductor layers and a plurality of second semiconductor layers alternately stacked over the substrate. One of the first semiconductor layers has a height greater than a height of one the second semiconductor layers. The first gate stack wraps around the stacked structure.

An indium phosphide substrate, a method of inspecting thereof and a method of producing thereof are provided, by which an epitaxial film grown on the substrate is rendered excellently uniform, thereby allowing improvement in PL characteristics and electrical characteristics of an epitaxial wafer formed using this epitaxial film. The indium phosphide substrate has a first main surface and a second main surface, a surface roughness Ra1 at a center position on the first main surface, and surface roughnesses Ra2, Ra3, Ra4, and Ra5 at four positions arranged equidistantly along an outer edge of the first main surface and located at a distance of 5 mm inwardly from the outer edge. An average value m1 of the surface roughnesses Ra1, Ra2, Ra3, Ra4, and Ra5 is 0.5 nm or less, and a standard deviation 1 of the surface roughnesses Ra1, Ra2, Ra3, Ra4, and Ra5 is 0.2 nm or less.

A semiconductor stack includes a substrate made of silicon carbide, and an epi layer disposed on the substrate and made of silicon carbide. An epi principal surface, which is a principal surface opposite to the substrate, of the epi layer is a carbon surface having an off angle of 4 or smaller relative to a c-plane. In the epi principal surface, a plurality of first recessed portions having a rectangular circumferential shape in a planar view is formed. Density of a second recessed potion that is formed in the first recessed portions and is a recessed portion deeper than the first recessed portions is lower than or equal to 10 cm.sup.2 in the epi principal surface.

There is provided a method of manufacturing a device, which comprises: a preparation step of preparing a workpiece having a recess formed therein; a burying step of burying a sacrificial material composed of a thermally decomposable organic material in the recess; a lamination step of laminating a preliminary sealing film on the sacrificial material buried in the recess; a first removal step of removing the sacrificial material in the recess through the preliminary sealing film, by annealing the workpiece at a first temperature and thermally decomposing the sacrificial material; a processing step of performing a predetermined process on a portion other than the recess in the workpiece, in a state in which the recess is covered with the preliminary sealing film; and a second removal step of removing the preliminary sealing film.