Central Research Institute of Electric Power Industry

The Kansai Electric Power Co., Inc.

The Kansai Electric Co., Inc.

Central Research Institution of Electrical Power Industry

Toshiyuki Miyanagi

Hidekazu Tsuchida

Tomonori Nakamura

Koji Nakayama

Isaho Kamata

Yoshitaka Sugawara

Katsunori Asano

Ryosuke Ishii

Masahiro Nagano

In a bipolar semiconductor device such that electrons and holes are recombined in a silicon carbide epitaxial film grown from the surface of a silicon carbide single crystal substrate at the time of on-state forward bias operation; an on-state forward voltage increased in a silicon carbide bipolar semiconductor device is recovered by shrinking the stacking fault area enlarged by on-state forward bias operation. In a method of this invention, the bipolar semiconductor device in which the stacking fault area enlarged and the on-state forward voltage has been increased by on-state forward bias operation, is heated at a temperature of higher than 350&#xb0; C.

Method for recovering an on-state forward voltage and, shrinking stacking faults in bipolar semiconductor devices, and the bipolar semiconductor devices

In a bipolar silicon carbide semiconductor device in which an electron and a hole recombine with each other during current passage within a silicon carbide epitaxial film grown from a surface of a silicon carbide single crystal substrate, an object described herein is the reduction of defects which are the nuclei of a stacking fault which is expanded by current passage, thereby suppressing the increase of the forward voltage of the bipolar silicon carbide semiconductor device. In a method for producing a bipolar silicon carbide semiconductor device, the device is subjected to a thermal treatment at a temperature of 300&#xb0; C. or higher in the final step of production. Preferably, the above-mentioned thermal treatment is carried out after the formation of electrodes and then the resulting bipolar silicon carbide semiconductor device is mounted in a package.

Process for producing silicon carbide semiconductor device

An intermediate metal film is formed between a Schottky electrode and a pad electrode. A Schottky barrier height between the intermediate metal film and a silicon carbide epitaxial film is equivalent to or higher than a Schottky barrier height between the Schottky electrode and the silicon carbide epitaxial film. By this configuration, an excess current and a leak current through a pin-hole can be suppressed even in the case in which a Schottky barrier height between the pad electrode and the silicon carbide epitaxial film is less than the Schottky barrier height between the Schottky electrode and the silicon carbide epitaxial film.

Schottky barrier diode and method for using the same

In a SiC bipolar semiconductor device with a mesa structure having a SiC drift layer of a first conductive type and a SiC carrier injection layer of a second conductive type that are SiC epitaxial layers grown from a surface of a SiC single crystal substrate, the formation of stacking faults and the expansion of the area thereof are prevented and thereby the increase in forward voltage is prevented. Further, a characteristic of withstand voltage in a reverse biasing is improved. An forward-operation degradation preventing layer is formed on a mesa wall or on a mesa wall and a mesa periphery to separate spatially the surface of the mesa wall from a pn-junction interface. In one embodiment, the forward-operation degradation preventing layer is composed of a silicon carbide low resistance layer of a second conductive type that is equipotential during the application of a reverse voltage. In another embodiment, the forward-operation degradation preventing layer is composed of a silicon carbide conductive layer of a second conductive type, and a metal layer that is equipotential during the application of a reverse voltage is formed on a surface of the silicon carbide conductive layer. In still another embodiment, the forward-operation degradation preventing layer is composed of a high resistance amorphous layer.

Silicon carbide bipolar semiconductor device

With a view to preventing increases in forward voltage due to a change with the lapse of time of a bipolar semiconductor device using a silicon carbide semiconductor, a buffer layer, a drift layer and other p-type and n-type semiconductor layers are formed on a growth surface, which is given by a surface of a crystal of a silicon carbide semiconductor having an off-angle &#x3b8; of 8 degrees from a (000-1) carbon surface of the crystal, at a film growth rate having a film-thickness increasing rate per hour h of 10 &#x3bc;m/h, which is three times or more higher than conventional counterparts. The flow rate of silane and propane material gases and dopant gases is largely increased to enhance the film growth rate.

Silicon carbide semiconductor device and manufacturing method therefor

A silicon carbide Schottky barrier semiconductor device provided with a Ta electrode as a Schottky electrode, in which the Schottky barrier height is controlled to a desired value in a range where power loss is minimized without increasing the n factor. The method for manufacturing the silicon carbide Schottky barrier semiconductor device includes the steps of depositing Ta on a crystal face of an n-type silicon carbide epitaxial film, the crystal face having an inclined angle in the range of 0&#xb0; to 10&#xb0; from a (000-1) C face, and carrying out a thermal treatment at a temperature range of 300 to 1200&#xb0; C. to form the Schottky electrode.

Schottky barrier semiconductor device and method for manufacturing the same

A process for producing a Schottky junction type semiconductor device includes the steps of forming a Schottky electrode on a surface of a silicon carbide epitaxial layer, wherein a Schottky electrode made of molybdenum, tungsten, or an alloy thereof is formed on the surface of the silicon carbide epitaxial layer and is subjected to heat treatment so as to induce an alloying reaction at an interface of the silicon carbide epitaxial layer and the Schottky electrode, thereby forming an alloy layer at the interface, whereby the height of a Schottky barrier is controlled while maintaining an n-factor at a nearly constant low value.

Growing community of inventors

Yokosuka, Japan

Toshiyuki Miyanagi