Heat treatment is performed twice with respect to a silicon carbide substrate. In the first heat treatment process, after Si ions are implanted in a front surface of the silicon carbide substrate, the silicon carbide substrate contacting an electrode film is heat treated, and a precursor layer of a thermal reaction layer is formed between the electrode film and the silicon carbide substrate that includes a high-concentration impurity region. Thereafter, the unreacted electrode film remaining on the precursor layer of the thermal reaction layer and on an oxide film is removed. In the subsequent second heat treatment process, the silicon carbide substrate from which the unreacted electrode film has been removed is heat treated and the precursor layer of the thermal reaction layer at a bottom area of the opening is converted into the thermal reaction layer.

A silicon carbide semiconductor device includes a silicon carbide semiconductor substrate; a nickel silicide film provided on a surface of the silicon carbide semiconductor substrate and functioning as an ohmic contact; and an extraction electrode contacting the ohmic contact on a side different from a silicon carbide semiconductor substrate side. The silicon carbide semiconductor substrate side of the ohmic contact is mainly formed from a NiSi phase and an extraction electrode side thereof is mainly formed from a Ni.sub.2Si phase. The ohmic contact includes carbon on the silicon carbide semiconductor substrate and includes no carbon on the extraction electrode side.

In a silicon carbide semiconductor device in which a contact electrode is formed on a single-crystal silicon carbide semiconductor substrate, a barrier metal (titanium nitride layer) covers an interlayer insulating film in a region other than a contact hole, and a contact electrode of a predetermined electrode material is formed only in a region on the silicon carbide semiconductor substrate in the contact hole opened in the interlayer insulating film on the silicon carbide semiconductor substrate. A top of the barrier metal is covered by a metal electrode (wiring layer) and no nickel metal aggregates are present between the barrier metal and the metal electrode.

An interlayer insulating film is formed on a gate insulating film and a gate electrode, and the interlayer insulating film is opened forming contact holes. Next, the interlayer insulating film and regions exposed by the contact holes are covered by a titanium nitride film, and the titanium nitride film is etched to remain only at portions of the gate insulating film and the interlayer insulating film exposed in the contact holes. The interlayer insulating film and the regions exposed by the contact holes are covered by a nickel film, and after the nickel film directly contacting the interlayer insulating film 8 is removed, the nickel film is heat treated and a nickel silicide layer is formed.

An interlayer insulating film is patterned, contact holes are formed, and in the contact holes, a source contact portion forming an ohmic contact with the silicon carbide body is formed. Thereafter, a titanium film and an aluminum wiring layer are continuously formed in this sequence on the interlayer insulating film and the source contact portion. At this time, the thickness of the titanium film is about 1.0 μm or less. Thereafter, by heat treatment for curing of a passivation film or heat treatment thereafter, the titanium film and the aluminum wiring layer react, generating a TiAl alloy film between the titanium film and the aluminum wiring layer. The thickness of the TiAl alloy film, for example, is kept to about 1 nm to 100 nm; and the TiAl alloy film and the source contact portion do not contact each other.

A silicon carbide semiconductor device includes an n.sup.+-type SiC substrate, a gate oxide film formed on a portion of the surface of the n.sup.+-type SiC substrate, a gate electrode formed on the gate oxide film, an interlayer insulating film formed so as to cover the gate electrode, a TiN film formed so as to cover the interlayer insulating film, and a Ni silicide layer formed on a surface of the n.sup.+-type SiC substrate not covered by the interlayer insulating film. The TiN film has two or more layers.

A semiconductor device includes first and second electrodes and a silicon carbide layer located between the first and second electrodes. A plurality of gate electrodes is interposed between the first electrode and the silicon carbide layer and extends in a first direction. The silicon carbide layer includes a plurality of spaced apart openings having sidewalls and a base which extend inwardly between the gate electrodes, a first region containing a second conductivity type impurity extending around and under the openings, and a second region containing a second conductivity type impurity interposed between the portion of the first region extending under the base of the openings. The concentration of the second conductivity type impurity is greater in the second region than in the first region. The silicon carbide layer includes a third region containing a first conductivity type impurity extending inwardly of the first region from the sidewall of the openings.

Process (A) of preparing a silicon carbide substrate of a first conductivity type; process (B) of forming an epitaxial layer of the first conductivity type on one principal surface of the silicon carbide substrate; process (C) of forming on another principal surface of the silicon carbide substrate, a first metal layer; process (D) of heat treating the silicon carbide substrate after the process (C) to form an ohmic junction between the first metal layer and the other principal surface of the silicon carbide substrate, and a layer of a substance (10) highly cohesive with another metal on the first metal layer; and a process (E) of removing impurities and cleaning a surface of the first metal layer (8) on the other principal surface of the silicon carbide substrate (D), are performed. The heat treatment at process (D) is executed at a temperature of 1,100 degrees C. or more.

A method of manufacturing a semiconductor device includes preparing a semiconductor layer having an element region and an outer peripheral region, forming a step portion surrounding the outer periphery of the element region in the outer peripheral region, and forming a metal layer along the step portion. The metal layer extends to cover at least a portion of a sidewall of the step portion. The method of manufacturing the semiconductor device further includes dividing the semiconductor layer into element regions on an outside of the step portion when viewed from the element region.

Flash light is emitted from flash lamps to the surface of a semiconductor substrate on which a metal layer has been formed for one second or less to momentarily raise temperature on the surface of the semiconductor substrate including the metal layer and an impurity region to a processing temperature of 1000° C. or more. Heat treatment is performed by emitting flash light to the surface of the semiconductor substrate in a forming gas atmosphere containing hydrogen. By heating the surface of the semiconductor substrate to a high temperature in the forming gas atmosphere for an extremely short time period, contact resistance can be reduced without desorbing hydrogen taken in the vicinity of an interface of a gate oxide film for hydrogen termination.