A vertical JFET with a ladder termination may be made by a method using a limited number of masks. A first mask is used to form mesas and trenches in active cell and termination regions simultaneously. A mask-less self-aligned process is used to form silicide source and gate contacts. A second mask is used to open windows to the contacts. A third mask is used to pattern overlay metallization. An optional fourth mask is used to pattern passivation. Optionally the channel may be doped via angled implantation, and the width of the trenches and mesas in the active cell region may be varied from those in the termination region.

A silicon carbide semiconductor device, including a silicon carbide semiconductor substrate, and an insulating film formed on a front surface of the silicon carbide semiconductor substrate. The silicon carbide semiconductor substrate has fluorine implanted therein, a concentration of which is in a range of 210.sup.17/cm.sup.3 to 410.sup.18/cm.sup.3. A method of manufacturing the silicon carbide semiconductor device includes providing a silicon carbide semiconductor substrate, forming an oxide film on a front surface of the silicon carbide semiconductor substrate, removing a portion of the oxide film to expose the silicon carbide semiconductor substrate, implanting fluorine ions in the front surface of the silicon carbide semiconductor substrate through the removed portion of the oxide film, removing the oxide film after the fluorine ions are implanted, and forming an insulating film on the front surface of the silicon carbide semiconductor substrate after the oxide film is removed.

A silicon carbide semiconductor device has a semiconductor substrate, a trench gate structure disposed in the semiconductor substrate, a first electrode electrically connected to an impurity region and a bae layer of the semiconductor substrate, a second electrode connected to a substrate, and an interlayer insulating film disposed between a gate electrode and the first electrode. The trench gate structure includes a gate insulating film disposed in a trench of the semiconductor substrate and the gate electrode disposed on the gate insulating film. A portion of the semiconductor substrate adjoining the trench has a termination structure in which dangling bonds are terminated with at least one of nitrogen, hydrogen or phosphorous. The interlayer insulating film has a contact insulating film that is in contact with the gate electrode. The contact insulating film is provided by a deposited film.

A vertical JFET with a ladder termination may be made by a method using a limited number of masks. A first mask is used to form mesas and trenches in active cell and termination regions simultaneously. A mask-less self-aligned process is used to form silicide source and gate contacts. A second mask is used to open windows to the contacts. A third mask is used to pattern overlay metallization. An optional fourth mask is used to pattern passivation. Optionally the channel may be doped via angled implantation, and the width of the trenches and mesas in the active cell region may be varied from those in the termination region.

A semiconductor device having a voltage resistant structure in a first aspect of the present invention is provided, comprising a semiconductor substrate, a semiconductor layer on the semiconductor substrate, a front surface electrode above the semiconductor layer, a rear surface electrode below the semiconductor substrate, an extension section provided to a side surface of the semiconductor substrate, and a resistance section electrically connected to the front surface electrode and the rear surface electrode. The extension section may have a lower permittivity than the semiconductor substrate. The resistance section may be provided to at least one of the upper surface and the side surface of the extension section.

A method of manufacturing a silicon carbide semiconductor device includes forming on a front surface of a silicon carbide substrate of a first conductivity type, a silicon carbide layer of the first conductivity type of a lower concentration; selectively forming a region of a second conductivity type in a surface portion of the silicon carbide layer; selectively forming a source region of the first conductivity type in the region; forming a source electrode electrically connected to the source region; forming a gate insulating film on a surface of the region between the silicon carbide layer and the source region; forming a gate electrode on the gate insulating film; forming a drain electrode on a rear surface of the substrate; forming metal wiring comprising aluminum for the device, the metal wiring being connected to the source electrode; and performing low temperature nitrogen annealing after the metal wiring is formed.

A semiconductor device according to an embodiment includes a silicon carbide layer, an insulating layer, and a region provided between the silicon carbide layer and the insulating layer, the region including a plurality of first atoms of one element from the group consisting of nitrogen (N), phosphorus (P), arsenic (As), antimony (Sb), and bismuth (Bi), at least some of the plurality of first atoms being four-fold coordinated atoms and/or five-fold coordinated atoms.

A semiconductor device manufacturing method of embodiments includes: performing first ion implantation for implanting aluminum into a silicon carbide layer with a first dose amount; performing first heat treatment at a temperature equal to or more than 1600? C.; performing first etching process for etching a surface of the silicon carbide layer in an atmosphere containing plasma generated from a gas containing halogen and oxygen; performing second etching process for etching the surface in an atmosphere containing hydrogen plasma or atomic hydrogen; forming a silicon oxide film on the surface; and forming a gate electrode on the silicon oxide film.

A vertical transistor device includes a silicon-carbide substrate, a gate trench formed in the silicon-carbide substrate, a body region adjacent the gate trench, a source region adjacent the gate trench and above the body region, and a dielectric material covering a bottom and a sidewall of the gate trench. A thickness of the dielectric material is greater at the bottom of the gate trench than along the sidewall of the gate trench. Further vertical transistor device embodiments and corresponding methods of manufacture are also described.

A MOSFET using a SiC substrate has a problem that a carbon-excess layer is formed on a surface by the application of mechanical stress due to thermal oxidation and the carbon-excess layer degrades mobility of channel carriers. In the invention, (1) a layer containing carbon-carbon bonds is removed; (2) a gate insulating film is formed by a deposition method; and (3) an interface between a crystal surface and the insulating film is subjected to an interface treatment at a low temperature for a short time. Due to this, the carbon-excess layer causing characteristic degradation is effectively eliminated, and at the same time, dangling bonds can be effectively eliminated by subjecting an oxide film and an oxynitride film to an interface treatment.