A silicon carbide semiconductor device is a SiC-SBD that has, in an active region, at a front surface of a semiconductor substrate containing silicon carbide, a mixture of a SBD structure having Schottky barrier junctions between a titanium film that is a lowermost layer of a front electrode and an n.sup.−-type drift region, and a JBS structure having pn junction portions between p-type regions and the n.sup.−-type drift region. The p-type regions form ohmic junctions with the titanium film that is the lowermost layer of the front electrode. After an ion implantation for the p-type regions, activation annealing is performed at a temperature in a range of 1700 degrees C. to 1900 degrees C. for a treatment time exceeding 20 minutes, whereby contact resistance between the titanium film and the p-type regions is adjusted to be in a range of about 5×10.sup.−4 Ω.Math.cm.sup.2 to 8×10.sup.−3 Ω.Math.cm.sup.2.

A silicon carbide epitaxial substrate includes a silicon carbide single crystal substrate and a silicon carbide layer. In a direction parallel to a central region, a ratio of a standard deviation of a carrier concentration of the silicon carbide layer to an average value of the carrier concentration of the silicon carbide layer is less than 5%. The average value of the carrier concentration is more than or equal to 1×10.sup.14 cm.sup.−3 and less than or equal to 5×10.sup.16 cm.sup.−3. In the direction parallel to the central region, a ratio of a standard deviation of a thickness of the silicon carbide layer to an average value of the thickness of the silicon carbide layer is less than 5%. The central region has an arithmetic mean roughness (Sa) of less than or equal to 1 nm. The central region has a haze of less than or equal to 50.

An aluminum alloy film includes an Al—Si—Mg alloy film containing at least 0.9% by weight to 1.1% by weight of Si and 0.1% by weight to 2.3% by weight of Mg, and the Al—Si—Mg alloy film contains Mg silicide crystals in Al crystals. A semiconductor device includes multiple gate trench structures, an interlayer insulating film covering the trench gate structures, an electrode film covering the interlayer insulating film, an insulating layer and a conductive layer covering the electrode film. The electrode film includes the Al—Si—Mg alloy film.

An SBD of a JBS structure has on a front side of a semiconductor substrate, nickel silicide films in ohmic contact with p-type regions and a FLR, and a titanium film forming a Schottky junction with an n.sup.−-type drift region. A thickness of each of the nickel silicide films is in a range from 300 nm to 700 nm. The nickel silicide films each has a first portion protruding from the front surface of the semiconductor substrate in a direction away from the front surface of the semiconductor substrate, and a second portion protruding in the semiconductor substrate from the front surface of the semiconductor substrate in a depth direction. A thickness of the first portion is equal to a thickness of the second portion. A width of the second portion is wider than a width of the first portion.

On a silicon carbide semiconductor substrate of a first conductivity type, a first semiconductor layer of the first conductivity type, a second semiconductor layer of a second conductivity type, first semiconductor regions of the first conductivity type, second semiconductor regions of the second conductivity type, a gate insulating film, gate electrodes, an interlayer insulating film, first electrodes, and a second electrode are formed. Each of the first electrodes are formed by depositing a lower Ni film, an Al film, and an upper Ni film and etching the films to be apart from the interlayer insulating film; sintering the lower Ni film by a heat treatment and thereby forming a Ni silicide film; depositing a Ti film, a TiN film, and an AlSi film; and etching the AlSi film.

Embodiments of the present invention provide a semiconductor device capable of improving both the thermal stability and contact resistance and a method for fabricating the same. According to an embodiment of the present invention, a semiconductor device may comprise: a contact plug over a substrate, wherein the contact plug includes: a silicide layer having a varying carbon content in a film, and a metal material layer over the silicide layer.

A semiconductor device according to an embodiment includes: a silicon carbide layer; a metal layer; and a conductive layer positioned between the silicon carbide layer and the metal layer, the conductive layer containing a silicide of one metal element (M) selected from the group consisting of nickel (Ni), palladium (Pd), and platinum (Pt), and the conductive layer having a carbon concentration of 1×10.sup.17 cm.sup.−3 or less.

A method for controlling Schottky barrier height in a semiconductor device includes forming an alloy layer including at least a first element and a second element on a first surface of a semiconductor substrate. The semiconductor substrate is a first element-based semiconductor substrate, and the first element and the second element are Group IV elements. A first thermal anneal of the alloy layer and the first element-based substrate is performed. The first thermal anneal causes the second element in the alloy layer to migrate towards a surface of the alloy layer. A Schottky contact layer is formed on the alloy layer after the first thermal anneal.

For the manufacturing of a vertical conduction silicon carbide electronic device, a work wafer, which has a silicon carbide substrate having a work face, is processed. A rough face is formed from the work face of the silicon carbide substrate. The rough face has a roughness higher than a threshold. A metal layer is deposited on the rough face and the metal layer is annealed, thereby causing the metal layer to react with the silicon carbide substrate, forming a silicide layer having a plurality of protrusions of silicide.

The fabrication method for a silicon carbide semiconductor device according to this disclosure includes a step of forming a dielectric film over part of a silicon carbide layer, a step of forming an ohmic electrode adjoining the dielectric film on the silicon carbide layer, a step of removing an oxidized layer on the ohmic electrode, a step of forming a mask with its opening on the side opposite to the side where the ohmic electrode is adjoining the dielectric film on the ohmic electrode having the oxidized layer removed and on the dielectric film, and a step of wet etching of a film to be etched with hydrofluoric acid with the mask formed. With the fabrication method for a silicon carbide semiconductor device described in this disclosure, it is possible to fabricate a silicon carbide semiconductor device with reduced failure.