Methods are disclosed for forming a multi-layer structure including highly controlled diffusion interfaces between alternating layers of different semiconductor materials. According to embodiments, during a deposition of semiconductor layers, the process is controlled to remain at low temperatures such that an inter-diffusion rate between the materials of the deposited layers is managed to provide diffusion interfaces with abrupt Si/SiGe interfaces. The highly controlled interfaces and first and second layers provide a multi-layer structure with improved etching selectivity. In an embodiment, a gate all-around (GAA) transistor is formed with horizontal nanowires (NWs) from the multi-layer structure with improved etching selectivity. In embodiments, horizontal NWs of a GAA transistor may be formed with substantially the same size diameters and silicon germanium (SiGe) NWs may be formed with all-in-one silicon (Si) caps.

A silicon carbide substrate includes an N-type silicon carbide substrate having a first surface and a second surface opposite to the first surface. The N-type silicon carbide substrate includes a semi-insulating silicon carbide region and an N-type silicon carbide region. The semi-insulating silicon carbide region extends inward from the first surface into the N-type silicon carbide substrate to a depth. The semi-insulating silicon carbide region includes nitrogen and a first dopant. The first dopant includes at least one of group VB elements, group VIIA elements, argon and silicon. The N-type silicon carbide region is adjacent to the semi-insulating silicon carbide region and includes nitrogen element.

Provided is a method of manufacturing a semiconductor device having a photodiode that has a shallow p-n junction and thus achieves high sensitivity to an ultraviolet ray, in which an oxide containing impurities at high concentration is deposited on the surface of the silicon substrate, and thereafter a diffusion region is formed to have a shallow junction by performing thermal diffusion of a rapid temperature change, with the use of a high-speed temperature rising and falling apparatus without using ion implantation into the silicon substrate.

In a general aspect, an apparatus can include a silicon carbide (SiC) trench gate MOSFET with improved operation due, at least in part, to a reduced gate capacitance. In the SiC trench gate MOSFET, a thick gate oxide can be formed on a bottom surface of the gate trench and a built-in channel, having a vertical portion and a lateral portion, can be formed to electrically connect a vertical inversion-layer channel, such as in a channel stopper layer, to a vertical JFET channel region and a drift region.

An active region through which current flows in a semiconductor device includes an n.sup.-type silicon carbide epitaxial layer formed on a front surface of an n.sup.+-type silicon carbide semiconductor substrate; a p-type layer becoming a channel region; a trench formed so as to be in contact with a p-type layer and having an oxide film and a gate electrode embedded therein; a p.sup.+-type layer arranged beneath the trench and between trenches; an n.sup.-type layer in contact with the p-type layer, a p.sup.+-type layer, and the trench, and arranged in contact with a p.sup.+-type layer or on a surface side of the semiconductor substrate; an n-type layer in contact with the n.sup.-type silicon carbide epitaxial layer and the p.sup.+-type layer, and having an impurity concentration higher than that of the n.sup.-type layer and that of the n.sup.-type silicon carbide epitaxial layer.

A method for manufacturing a silicon carbide semiconductor device includes the steps of preparing a silicon carbide substrate having a first main surface and a second main surface located on a side opposite to the first main surface, forming an epitaxial layer on the first main surface, the epitaxial layer having a first conductivity type and having a third main surface located on a side opposite to a side on which the silicon carbide substrate is located, forming a trench, which includes side walls intersecting with the third main surface and a bottom portion connected to the side walls, in the epitaxial layer, widening an opening of the trench, and forming an embedded region, which has a second conductivity type different from the first conductivity type, in the trench. The epitaxial layer adjacent to the embedded region and the embedded region constitute a superjunction structure.

In a silicon carbide semiconductor device, a trench penetrates a source region and a first gate region and reaches a drift layer. On an inner wall of the trench, a channel layer of a first conductivity-type is formed by epitaxial growth. On the channel layer, a second gate region of a second conductivity-type is formed. A first depressed portion is formed at an end portion of the trench to a position deeper than a thickness of the source region so as to remove the source region at the end portion of the trench. A corner portion of the first depressed portion is covered by a second conductivity-type layer.

A manufacturing method of a semiconductor device is provided by forming a trench in a surface of a SiC substrate, positioning a protective substrate to cover the trench, and annealing the SiC substrate and the protective substrate.

A method of forming a semiconductor device is provided such that a trench is formed in a semiconductor body at a first surface of the semiconductor body. Dopants are introduced into a first region at a bottom side of the trench by ion implantation. A filling material is formed in the trench. Dopants are introduced into a second region at a top side of the filling material. Thermal processing of the semiconductor body is carried out and is configured to intermix dopants from the first and the second regions by a diffusion process along a vertical direction perpendicular to the first surface.

A method of manufacturing a silicon carbide semiconductor device includes a step of preparing a silicon carbide substrate having a first main surface and a second main surface located opposite to the first main surface, a step of forming a doped region in the silicon carbide substrate by doping the first main surface with an impurity, a step of forming a first protecting film on the first main surface, and a step of forming a second protecting film on the second main surface, the step of forming a first protecting film being performed after the step of forming a doped region, the method further including a step of activating the impurity included in the doped region by annealing with at least a portion of the first main surface covered with the first protecting film and at least a portion of the second main surface covered with the second protecting film.