An embodiment relates to a method obtaining a silicon carbide wafer comprising a first conductivity type substrate and a first conductivity type drift layer, forming a second conductivity type first well region within the first conductivity type drift layer, forming a first conductivity type source region within the second conductivity type first well region, forming a second conductivity type plug region under the first conductivity type source region, forming a gate oxide layer, forming a patterned gate metal layer, depositing an interlevel dielectric (ILD) layer, forming a first patterned mask layer on top of the ILD layer, and etching the ILD layer and the first conductivity type source region using the first patterned mask layer, and forming a silicide layer, wherein the silicide layer is in contact with a vertical sidewall of the first conductivity type source region and at-least one second conductivity type region.

A semiconductor device includes a semiconductor layer of a first conductivity type. A well region that is a second conductivity type well region is formed on a surface layer portion of the semiconductor layer and has a channel region defined therein. A source region that is a first conductivity type source region is formed on a surface layer portion of the well region. A gate insulating film is formed on the semiconductor layer and has a multilayer structure. A gate electrode is opposed to the channel region of the well region where a channel is formed through the gate insulating film.

A method of forming a contact structure for a silicon carbide semiconductor device, the method comprises the following steps in the following order: forming a gate structure for a transistor comprising a source region in a semiconductor layer; forming a silicide layer on the source region, wherein the silicide layer is self-aligned with the gate structure; providing a dielectric layer over the silicide layer; patterning the dielectric layer to form an opening to the silicide layer; and providing a metal in the opening to form an electric contact to the source region.

A SiC semiconductor device manufacturing method includes a step of etching a surface of a SiC substrate 1 with H.sub.2 gas under Si-excess atmosphere within a temperature range of 1000 C. to 1350 C., a step of depositing, by a CVD method, a SiO.sub.2 film 2 on the SiC substrate 1 at such a temperature that the SiC substrate 1 is not oxidized, and a step of thermally treating the SiC substrate 1, on which the SiO.sub.2 film 2 is deposited, in NO gas atmosphere within a temperature range of 1150 C. to 1350 C.

A bottom of a trench is an Si plane or a C plane while sidewalls of the trench are an m-plane. In the trench, a gate electrode is provided via a gate insulating film. The gate insulating film is a HTO film with a thickness of at least 50 nm. By a post-HTO-deposition annealing at a temperature in a range of 1250 degrees C. to 1300 degrees C. under a mixed gas atmosphere containing nitric oxide, nitrogen, and oxygen, the film density of the gate insulating film is within a range of 2.21 g/cm.sup.3 to 2.38 g/cm.sup.3. The total oxygen flow amount of the mixed gas atmosphere of the post-HTO-deposition annealing is at most 5%. The gate insulating film has a two-layer structure including a low-density film that is within 3 nm from a SiC/SiO.sub.2 interface and has a relatively low film density, and a high-density film that is at least 3 nm apart from the SiC/SiO.sub.2 interface and has a relatively high film density.

A method for producing a semiconductor power device includes forming a gate trench from a surface of the semiconductor layer toward an inside thereof. A first insulation film is formed on the inner surface of the gate trench. The method also includes removing a part on a bottom surface of the gate trench in the first insulation film. A second insulation film having a dielectric constant higher than SiO2 is formed in such a way as to cover the bottom surface of the gate trench exposed by removing the first insulation film.

A method of forming a semiconductor device includes forming a gate oxide layer over an epitaxial layer including a drift region and a source region, forming a first boron-containing layer over the gate oxide layer, performing a thermal process, such that the boron in the first boron-containing layer moves in a direction toward the epitaxial layer to form a second boron-containing layer between the epitaxial layer and the gate oxide layer, and forming a gate over the gate oxide layer.

A method of manufacturing a semiconductor device includes: preparing semiconductor substrate having a front surface and a back surface opposite to each other, the semiconductor substrate being of a first conductivity type; forming a device structure in the semiconductor substrate, at the front surface; performing thermal oxidation to form a gate insulating film and depositing a polysilicon to form a plurality of gate electrodes; removing the polysilicon at the back surface of the semiconductor substrate while leaving an oxide film formed at the back surface and a side surface of the semiconductor substrate by the thermal oxidation; forming a surface electrode on the device structure; and forming a plating film on the surface electrode while continuing to leave the oxide film at the back surface and the side surface of the semiconductor substrate.

A new design of a silicon carbide (SiC) metal-oxide-semiconductor field-effect transistor (MOSFET) and method of manufacturing the MOSFET are disclosed. The SiC MOSFET features a trench formed in SiC layers that includes a buried p-well region near the bottom of the trench that extends along a sidewall of the trench. The SiC MOSFET may also include a p-body and built-in channel on an opposite sides of the trench. The SiC MOSFET configurations may help prevent dielectric breakdown and bipolar degradation in the SiC.

A semiconductor device includes a semiconductor region made of a material to which conductive impurities are added, an insulating film formed on a surface of the semiconductor region, and an electroconductive gate electrode formed on the insulating film. The gate electrode is made of a material whose Fermi level is closer to a Fermi level of the semiconductor region than a Fermi level of Si in at least a portion contiguous to the insulating film.