National Institute of Advanced Industrial Science and Technology

Fuji Electric Co., Ltd.

Sanyo Electric Co., Ltd.

Mitsuo Okamoto

Kenji Fukuda

Shinsuke Harada

Tsutomu Yatsuo

Takashi Tsutsumi

Tsuyoshi Araoka

Youichi Makifuchi

Seiji Suzuki

Yoshiyuki Sakai

Junji Senzaki

Kazuhiro Adachi

Makoto Kato

Naoki Kumagai

Makoto Utsumi

Yasuhiko Oonishi

Tsunehiro Nakajima

Naoyuki Ohse

Fumikazu Imai

Takumi Fujimoto

Masaki Miyazato

Ryoji Kosugi

Yoshiyuki Sugahara

Yohei Iwahashi

Takahiro Nagano

A silicon nitride film having a thickness in a range from 1 [nm] to 3 [nm] is deposited on a front surface of a silicon carbide semiconductor base, by an ALD method. Next, on the silicon nitride film, for example, a silicon oxide film having a thickness in a range from 20 [nm] to 100 [nm] is deposited. After deposition of the silicon oxide film, for example, heat treatment is performed at a temperature in a range from 1100 degrees C. to 1350 degrees C., in a gas atmosphere that includes oxygen. By this heat treatment, nitrogen surface density of an interface of the silicon carbide semiconductor base and the silicon oxide film (gate insulating film) is increased, reducing interface state density of the interface of the silicon carbide semiconductor base and the silicon nitride film.

Silicon carbide semiconductor device and method of manufacturing silicon carbide semiconductor device

In forming an ohmic electrode on a back surface of an n-type SiC substrate, an n-type semiconductor region is formed in a surface layer of the back surface of an n-type epitaxial substrate by ion implantation. In this ion implantation, the impurity concentration of the n-type semiconductor region is a predetermined range and preferably a predetermined value or less, and an n-type impurity is implanted by acceleration energy of a predetermined range such that the n-type semiconductor region has a predetermined thickness or less. Thereafter, a nickel layer and a titanium layer are sequentially formed on the surface of the n-type semiconductor region, the nickel layer is heat treated to form a silicide, and the ohmic electrode formed from nickel silicide is formed. In this manner, a back surface electrode that has favorable properties can be formed while peeling of the back surface electrode can be suppressed.

A silicon carbide semiconductor device includes a silicon carbide semiconductor substrate of a first conductivity type, a gate insulating film provided on a front surface of the silicon carbide semiconductor substrate and including any one or a plurality of an oxide film, a nitride film, and an oxynitride film, and a gate electrode containing poly-silicon and provided on the gate insulating film. A concentration of fluorine in the gate insulating film at an interface with the silicon carbide semiconductor substrate is equal to or higher than 1&#xd7;10atoms/cm.

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 2&#xd7;10/cmto 4&#xd7;10/cm. 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 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.

Method of manufacturing silicon carbide semiconductor device and silicon carbide semiconductor device

A silicon carbide semiconductor device, including a silicon carbide semiconductor structure, an insulated gate structure including a gate insulating film contacting the silicon carbide semiconductor structure and a gate electrode formed on the gate insulating film, an interlayer insulating film covering the insulated gate structure, a metal layer provided on the interlayer insulating film for absorbing or blocking hydrogen, and a main electrode provided on the metal layer and electrically connected to the silicon carbide semiconductor structure.

In producing a MOS silicon carbide semiconductor device, after a first heat treatment (oxynitride) is performed in an oxidation atmosphere including nitrous oxide or nitric oxide, a second heat treatment including hydrogen is performed, whereby in the front surface of a SiC epitaxial substrate, a gate insulating film is formed. A gate electrode is formed and after an interlayer insulating film is formed, a third heat treatment is performed to bake the interlayer insulating film. After contact metal formation, a fourth heat treatment is performed to form a reactive layer of contact metal and the silicon carbide semiconductor. The third and fourth heat treatments are performed in an inert gas atmosphere of nitrogen, helium, argon, etc., and a manufacturing method of a silicon carbide semiconductor device is provided achieving a normally OFF characteristic and lowered interface state density.

Manufacturing method of silicon carbide semiconductor device

On a silicon carbide semiconductor substrate, heat treatment is performed after one layer or two or more layers of an oxide film, a nitride film, or an oxynitride film are formed as a gate insulating film. The heat treatment after the gate insulating film is formed is performed for a given period in an atmosphere that includes Hand HO without including O. As a result, hydrogen or hydroxyl groups can be segregated in a limited region that includes the interface of the silicon carbide substrate and the gate insulating film. The width of the region to which the hydrogen or hydroxyl groups is segregated is from 0.5 nm to 10 nm. In such a manner, the interface state density can be lowered and high channel mobility can be realized.

Silicon carbide semiconductor device and manufacturing method of silicon carbide semiconductor device

An infrared ray absorbing film is selectively formed on a surface of a silicon carbide semiconductor substrate in a predetermined area. The infrared ray absorbing film is composed of one of a multi-layered film of titanium nitride and titanium, a multi-layered film of molybdenum nitride and molybdenum, a multi-layered film of tungsten nitride and tungsten, or a multi-layered film of chromium nitride and chromium. An aluminum film and a nickel film are sequentially formed in this order on the silicon carbide semiconductor substrate in an area excluding the predetermined area in which the infrared ray absorbing film is formed. The silicon carbide semiconductor substrate is thereafter heated using a rapid annealing process with a predetermined heating rate to form an electrode. The rapid annealing process converts the nickel film into a silicide and, with the aluminum film, provides an electrode having ohmic contact.

Silicon carbide semiconductor device and method of manufacturing a silicon carbide semiconductor device

A silicon carbide vertical MOSFET having low ON-resistance and high blocking voltage is provided. For this, a first deposition film () of low concentration silicon carbide of a first conductivity type is formed on the surface of a high concentration silicon carbide substrate () of a first conductivity type. Formed on the first deposition film () is a second deposition film () that comprises a high concentration gate region of a second conductivity type, with a first region removed selectively. A third deposition film () formed on the second deposition film, which comprises a second region that is wider than the selectively removed first region, a high concentration source region () of a first conductivity type and a low concentration gate region () of a second conductivity type. A low concentration base region () of a first conductivity type is formed in contact with the first deposition film () in the first and second regions.

Silicon carbide semiconductor apparatus and method of manufacturing same

A silicon carbide vertical MOSFET having low ON-resistance and high blocking voltage. A first deposition film of low concentration silicon carbide of a first conductivity type is formed on the surface of a high concentration silicon carbide substrate of a first conductivity type. Formed on the first deposition film is a second deposition film that includes a high concentration gate region of a second conductivity type, with a first region removed selectively. A third deposition film is formed on the second deposition film, which includes a second region that is wider than the selectively removed first region, a high concentration source region of a first conductivity type, and a low concentration gate region of a second conductivity type. A low concentration base region of a first conductivity type is formed in contact with the first deposition film in the first and second regions.

Silicon carbide semiconductor device and its manufacturing method

A SiC MISFET, in which a source region and a drain region () are formed in a one-conductivity-type SiC semiconductor region (), in which a recess () with a predetermined depth is formed in a portion of the SiC semiconductor region sandwiched between the source and drain regions, with the recess having two side faces in contact with the source and drain regions, and a bottom face connecting the two side faces, and in which portions () of the source and drain regions adjacent to the vicinity of both ends of the bottom face of the recess are thinner than other portions.

Recessed gate-type silicon carbide field effect transistor and method of producing same

This invention has a cell incorporating a built-in Schottky diode region disposed in at least part of an elementary cell that constitutes an SiC vertical MOSFET provided in a low-density p-type deposit film with a channel region and a base region inverted to an n-type by ion implantation. This built-in Schottky diode region has built therein a Schottky diode of low on-resistance that is formed of a second deficient pan disposed in a high-density gate layer, a second n-type base layer penetrating a low-density p-type deposit layer formed thereon, reaching an n-type drift layer of the second deficient part and attaining its own formation in consequence of inversion of the p-type deposit layer into an n-type by the ion implantation of an n-type impurity from the surface, and a source electrode connected in the manner of forming a Schottky barrier to the surface-exposed part of the second n-type base layer.

Silicon carbide MOS field effect transistor with built-in Schottky diode and method for fabrication thereof

A semiconductor device and a method of manufacturing the device using a (000-1)-faced silicon carbide substrate are provided. A SiC semiconductor device having a high blocking voltage and high channel mobility is manufactured by optimizing the heat-treatment method used following the gate oxidation. The method of manufacturing a semiconductor device includes the steps of forming a gate insulation layer on a semiconductor region formed of silicon carbide having a (000-1) face orientation, forming a gate electrode on the gate insulation layer, forming an electrode on the semiconductor region, cleaning the semiconductor region surface. The gate insulation layer is formed in an atmosphere containing 1% or more HO (water) vapor at a temperature of from 800&#xb0; C. to 1150&#xb0; C. to reduce the interface trap density of the interface between the gate insulation layer and the semiconductor region.

Semiconductor device and method of manufacturing same

In an SiC vertical MOSFET comprising a channel region and an n-type inverted electron guide path formed through ion implantation in a low-concentration p-type deposition film, the width of the channel region may be partly narrowed owing to implantation mask positioning failure, and the withstand voltage of the device may lower, and therefore, the device could hardly satisfy both low on-resistance and high withstand voltage. In the invention, second inverted layers () are provided at the same distance on the right and left sides from the inverted layer () to be the electron guide path in the device, and the inverted layers are formed through simultaneous ion implantation using the same mask, and accordingly, the length of all the channel regions in the device is made uniform, thereby solving the problem.

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Tsukuba, Japan

Mitsuo Okamoto