A MOSFET includes: a SiC layer including one main surface and provided with a plurality of contact regions; and a plurality of source electrodes formed in contact with the contact regions. In the MOSFET, in a plan view of the one main surface, a plurality of cells including the contact regions and the source electrodes are formed adjacent to one another, each of the plurality of cells having an outer circumferential shape that is a shape of hexagon including a long axis. According to the MOSFET, a contact resistance between each contact region and each source electrode can be further reduced, thereby attaining a more improved electrical property.

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.

A semiconductor substrate having a main surface and made of a wide band gap semiconductor is provided, the semiconductor substrate including a device region formed in the semiconductor substrate, and a peripheral region formed to surround the device region. In the peripheral region, the semiconductor substrate includes a first semiconductor region having a first conductivity type, and a second semiconductor region formed on the first semiconductor region and having the main surface, the second semiconductor region having a second conductivity type different from the first conductivity type. At an outermost periphery of the peripheral region, the semiconductor substrate has a plurality of stepped portions annularly surrounding the device region, and the second semiconductor region is formed along the stepped portion.

A method for manufacturing a silicon carbide substrate includes the following steps. There is prepared a silicon carbide single crystal substrate having a first main surface, a second main surface, and a first side end portion, the second main surface being opposite to the first main surface, the first side end portion connecting the first main surface and the second main surface to each other, the first main surface having a width with a maximum value of more than 100 mm. A silicon carbide epitaxial layer is formed in contact with the first side end portion, the first main surface, and a boundary between the first main surface and the first side end portion. The silicon carbide epitaxial layer formed in contact with the first side end portion and the boundary is removed.

A semiconductor device includes a first silicon carbide semiconductor layer, a source including a source pad and a source wiring, a gate including a gate pad and a gate wiring, first unit cells disposed in a first element region, and second unit cells disposed in a second element region. In a plan view, the first and second element regions are adjacent to each other with the gate wiring between the first and second element regions. A first electrode including the gate electrode of each first unit cell is disposed in the first element region and electrically connected to the gate. A second electrode including the gate electrode of each second unit cell is disposed in the second element region and not electrically connected to the gate. The first and second electrodes are separated below the gate wiring.

Semiconductor devices comprising a getter material are described. The getter material can be located in or over the active region of the device and/or in or over a termination region of the device. The getter material can be a conductive or an insulating material. The getter material can be present as a continuous or discontinuous film. The device can be a SiC semiconductor device such as a SiC vertical MOSFET. Methods of making the devices are also described. Semiconductor devices and methods of making the same comprising source ohmic contacts formed using a self-aligned process are also described. The source ohmic contacts can comprise titanium silicide and/or titanium silicide carbide and can act as a getter material.

A method of manufacturing a silicon carbide semiconductor device includes grinding a back surface of a semiconductor substrate formed of silicon carbide to reduce thickness thereof and provide an altered layer that is ground; removing by polishing or etching, the altered layer from the back surface; forming a nickel film on the back surface of the semiconductor substrate after removing the altered layer; heat treating the nickel film to forming a nickel silicide layer by silicidation; and forming a metal electrode on a surface of the nickel silicide layer.

A silicon carbide field effect transistor includes a silicon carbide substrate, an n-type drift layer, a p-type epitaxy layer, a source region, a trench gate, at least one p-type doped region, a source, a dielectric layer and a drain. The p-type doped region is disposed at the n-type drift layer to be adjacent to one lateral side of the trench gate, and includes a first doped block and a plurality of second doped blocks arranged at an interval from the first doped block towards the silicon carbide substrate. Further, a thickness of the second doped blocks does not exceed 2 um. Accordingly, not only the issue of limitations posed by the energy of ion implantation is solved, but also an electric field at a bottom and a corner of the trench gate is effectively reduced, thereby enhancing the reliability of the silicon carbide field effect transistor.

In one general aspect, an apparatus can include a silicon carbide (SiC) device can include a gate dielectric, a first doped region having a first conductivity type, a body region of the first conductivity type, and a second doped region having a second conductivity type. The second doped region has a first portion disposed between the first doped region and the body region, and the second doped region has a second portion disposed between the first doped region and the gate dielectric.

A silicon carbide substrate has first to third semiconductor layers. The first and third semiconductor layers have a first conductivity type, and the second semiconductor layer has a second conductivity type. A trench has a bottom surface and first to third side surfaces, the bottom surface being constituted of the first semiconductor layer, the first to third side surfaces being respectively constituted of the first to third semiconductor layers. A gate insulating film having a bottom portion and a side wall portion is provided on the trench. The bottom portion has a minimum thickness d.sub.0. A portion of the side wall portion on the second side surface has a minimum thickness d.sub.1. A portion, connected to the bottom portion, of the side wall portion on the first side surface has a thickness d.sub.2. Moreover, d.sub.2>d.sub.1 and d.sub.2>d.sub.0 are satisfied.