A semiconductor device includes an n.sup.+ type silicon carbide substrate, and in the substrate an active region where primary current flows and an edge termination area surrounding the active region. The semiconductor device has a first p-type region and a second p-type region in the edge termination area, and the first p-type region includes therein a plurality of third p-type regions, and the second p-type region includes therein a plurality of fourth p-type regions. The widths between the respective plurality of third p-type regions and the widths between the respective plurality of fourth p-type regions become greater further away from the active region.

A semiconductor device includes a substrate including a plurality of transistor devices formed thereon, at least an epitaxial structure formed in between the transistor devices, and a tri-layered structure formed on the epitaxial structure. The epitaxial structure includes a first semiconductor material and a second semiconductor material, and a lattice constant of the second semiconductor material is larger than a lattice constant of the first semiconductor material. The tri-layered structure includes an undoped epitaxial layer, a metal-semiconductor compound layer, and a doped epitaxial layer sandwiched in between the undoped epitaxial layer and the metal-semiconductor compound layer. The undoped epitaxial layer and the doped epitaxial layer include at least the second semiconductor material.

A method for manufacturing a semiconductor substrate may comprise irradiating a surface of a first semiconductor layer and a surface of a second semiconductor layer with one or more types of first impurity in a vacuum. The method may comprise bonding the surface of the first semiconductor layer and the surface of the second semiconductor layer to each other in the vacuum. The method may comprise applying heat treatment to the semiconductor substrate produced in the bonding. The first impurity may be an inert impurity that does not generate carriers in the first and second semiconductor layers. The heat treatment may be applied such that a width of an in-depth concentration profile of the first impurity contained in the first and second semiconductor layers is narrower after execution of the heat treatment than before the execution of the heat treatment.

A semiconductor device is provided. The device may include a semiconductor layer; and a doped well disposed in the semiconductor layer and having a first conductivity type. The device may also include a drain region, a source region, and a body region, where the source and body regions may operate in different voltages. Further, the device may include a first doped region having a second conductivity type, the first doped region disposed between the source region and the doped well; and a second doped region having the first conductivity type and disposed under the source region. The device may include a third doped region having the second conductivity type and disposed in the doped well; and a fourth doped region disposed above the third doped region, the fourth doped region having the first conductivity type. Additionally, the device may include a gate and a field plate.

According to an embodiment of a method for fabricating a trench field-effect transistor (trench FET), the method includes: forming a trench in a semiconductor substrate of a first conductivity type, the trench including sidewalls which taper from a wider, top portion of the trench to a narrower, bottom portion of the trench; forming a gate dielectric in the trench, the gate dielectric having substantially the same thickness in the wider, top portion of the trench as in the narrower, bottom portion of the trench; forming a gate electrode in the trench and separated from the semiconductor substrate by the gate dielectric; and forming a channel region of a second conductivity type in the semiconductor substrate after forming the trench and the gate dielectric, the channel region being disposed adjacent the trench. Trench FETs formed by the method are also disclosed.

A semiconductor device includes a semiconductor substrate and a control electrode provided on a first surface side of the semiconductor substrate. The semiconductor substrate includes a first area on the first surface side and two second areas on the first surface side of the first area. The two second areas are arranged along the first surface. The control electrode provided above a portion of the first area between the two second areas. The first area includes a main portion and a peripheral edge portion extending outward from the main portion along the first surface. A depth of the peripheral edge portion from the first surface is shallower than a depth of the main portion from the first surface; and the peripheral edge portion has a concentration of second conductivity type impurities lower than a concentration of the second conductivity type impurities at a surface of the main portion.

A JFET having vertical and horizontal channel elements may be made from a semiconductor material such as silicon carbide using a first mask for multiple implantations to form a horizontal planar JFET region comprising a lower gate, a horizontal channel, and an upper gate, all above a drift region resting on a drain substrate region, such that the gates and horizontal channel are self-aligned with the same outer size and outer shape in plan view. A second mask may be used to create a vertical channel region abutting the horizontal channel region. The horizontal channel and vertical channel may each have multiple layers with varying doping concentrations. Angled implantations may use through the first mask to implant portions of the vertical channel regions. The window of the second mask may partially overlap the horizontal JFET region to insure abutment of the vertical and horizontal channel regions.

In one embodiment, a trench Schottky rectifier includes a termination trench and active trenches provided in a semiconductor layer. The active trenches are configured to be at a shallower depth than the termination trench to provide a trench depth difference. The selected trench depth difference in combination with one or more of the dopant concentration of the semiconductor layer, the thickness of the semiconductor layer, active trench width to termination trench width, and/or dopant profile of the semiconductor layer provide a semiconductor device having improved performance characteristics.

An object is to obtain a semiconductor device having a high sensitivity in detecting signals and a wide dynamic range, using a thin film transistor in which an oxide semiconductor layer is used. An analog circuit is formed with the use of a thin film transistor including an oxide semiconductor which has a function as a channel formation layer, has a hydrogen concentration of 510.sup.19 atoms/cm.sup.3 or lower, and substantially functions as an insulator in the state where no electric field is generated. Thus, a semiconductor device having a high sensitivity in detecting signals and a wide dynamic range can be obtained.

A Schottky device includes a plurality of mesa structures where one or more of the mesa structures includes a doped region having a multi-concentration dopant profile. In accordance with an embodiment, the Schottky device is formed from a semiconductor material of a first conductivity type. Trenches having sidewalk and floors are formed in the semiconductor material to form a plurality of mesa structures. A doped region having a multi-concentration impurity profile is formed in at least one trench, where the impurity materials of the doped region having the multi-concentration impurity profile are of a second conductivity type. A Schottky contact is formed to at least one of the mesa structures having the dope region with the multi-concentration impurity profile.