Hitachi, Ltd.

Tsutomu Yatsuo

Nobutake Konishi

Saburo Oikawa

Takahiro Nagano

Masahiro Okamura

Tatsuya Kamei

Shin Kimura

Takuzo Ogawa

Takayuki Iwasaki

Toshiyuki Ohno

Masayoshi Naito

Yoshitaka Sugawara

Hidekatsu Onose

Yukimasa Satou

Hiroshi Fukui

Takeshi Yokota

Atsuo Watanabe

Akira Horie

Susumu Murakami

Isamu Sanpei

Masahiro Nagasu

Naohiro Momma

Jin Onuki

Takaya Suzuki

Yoshio Terasawa

Hisao Amano

Tomoyuki Tanaka

Yoshiteru Shimizu

Hideo Kobayashi

Yuzo Kozono

Masaaki Takahashi

Fumio Sato

Daisuke Kawase

Keiichi Morita

Tomio Yasuda

Yohsuke Inoue

Mitsuo Yanagi

Katsumi Akabane

Teruyuki Kagami

Koichi Wajima

Hideo Honma

Tetsuo Mizoguchi

Kenji Yagishita

Saburou Oikawa

Toshiyuki Oono

Yukimasa Sato

In a static induction transistor, in addition to a first gate layer ( ), a plurality of second gate layers ( ) having a shallower depth and a narrower gap therebetween than those of the first gate layer ( ) are provided in an area surrounded by the first gate layer ( ), thereby an SiC static induction transistor with an excellent off characteristic is realized, while ensuring a required processing accuracy during production thereof.

Static induction transistor

To reduce the field intensity on the termination surface, almost not affecting the on-characteristic, a drift layer is made of two layers, an n-layer and n layer, and a termination region is formed on the surface of the above n layer. An impurity concentration ratio between the n layer and the n-layer is less than 1:2, and the thickness of the n layer is less than that of a source n layer. Reliability can be secured even in a high temperature operation.

Semiconductor device and power converter using the same

The present semiconductor switching device comprises a silicon carbide single crystal of hexagonal symmetry having a first conductive type and a semiconductor region of a second conductive type opposite to the first conductive type and locating in the silicon carbide single crystal. The silicon carbide single crystal of the first conductive type and the semiconductor region of the seconductive type form a pn junction. The pn junction interface has an interface extended in the depth direction from the surface of the silicon carbide single crystal, and the interface includes a crystal plane in parallel to the <11 0> orientation of the silicon carbide single crystal or approximately in parallel thereto, thereby reducing the leak current.

Silicon carbide semiconductor switching device

A wide bandgap semiconductor single crystal is applied as a semiconductor substrate material of a semiconductor surge absorber, and a surge absorption operation starting voltage is set by a punchthrough of a pn junction, to obtain a semiconductor surge absorber with a repetitive operation and a high surge endurance.

Semiconductor surge absorber, electrical-electronic apparatus, and power module using the same

In a silicon carbide static induction transistor, at a surface part of a semiconductor substrate, a p-type gate region is formed partially overlapping a n-type source region, whereby the high accuracy in alignment between the gate region and the source region is not required, and the gate withstand voltage can be highly increased since the substrate is made of silicon carbide, which improves the yield of static induction transistors.

Static induction semiconductor device, and driving method and drive circuit thereof

A power converting apparatus comprising a group of semiconductor switches and DC terminals electrically connected to the group of semiconductor switches, in which a clamping circuit is connected to the semiconductor switches or the DC terminals. Otherwise, a diode having a wide band gap is connected in parallel with a snubber diode or a snubber capacitor of a snubber circuit connected in parallel with the semiconductor switches. With such arrangement, an overvoltage or oscillating voltage impressed on the semiconductor switches is suppressed.

Power converter with clamping circuit

There is provided a semiconductor substrate which includes a pair of main surfaces, a first semiconductor layer of a first conductivity type adjacent to one of the main surface, a second semiconductor layer of a second conducting type of which impurity concentration is lower than that of the first semiconductor layer and which is adjacent to the first semiconductivity, a third semiconductor layer of the first conductivity type adjacent to the second semiconductor, and a fourth semiconductor of the second conductivity type of which impurity concentration is higher than that of the third semiconductor and which is adjacent to the other of the main surfaces and the third semiconductor. The device further includes one main electrode in ohmic-contact with the first semiconductor layer on one of the main surfaces of said semiconductor substrate, the other main electrode in ohmic-contact with the first semiconductor layer on the other of the main surfaces of said semiconductor substrate, and a control electrode connected electrically to the third semiconductor layer. The total amount of impurities of said third semiconductor layer is less than 10.sup.14 cm.sup.-2.

Semiconductor thyristor switching device and power converter using same

To provide a field-effect transistor having a large power conversion capacity and its fabrication method by decreasing the leakage current between the source and the drain of a semiconductor device made of hexagonal-system silicon carbide when the gate voltage of the semiconductor device is turned off and also decreasing the electrical resistance of the semiconductor device when the gate voltage of the semiconductor device is turned on. The main current path of the field-effect transistor is formed so that the current flowing between the source and the drain of, for example, a field-effect transistor flows in the direction parallel with the {0001} plane and a channel forming plane is parallel with the {1120} plane. �Selected Drawing!FIG. 1

Semiconductor device for improved power conversion having a

In a turn off type semiconductor device, an n-type emitter layer is divided into a plurality of elements by trenches. A silicide layer of a high melting point metal is provided on a p-type layer adjacent to the individual elements of the n-type emitter layer on a bottom of each of the trenches. A gate electrode is provided on the associated silicide layer so as to surround the plurality of elements of the n-type emitter layer obtained by the division of the emitter layer. An insulator is filled in each of the trenches dividing the n-type emitter layer surrounded by the gate electrode. A cathode electrode is provided on both the insulators and the n-type emitter layer.

Turn off type semiconductor device, method of producing the same and the

A gate turn-off thyristor includes a cathode emitter of n-type, a cathode base of p-type, an anode base of n-type and an anode emitter of p-type. A gate electrode is electrically connected to the p cathode base to enclose and define an elemental gate turn-off thyristor region. A plurality of n cathode emitter regions are arranged in proximity to each other in the elemental gate turn-off thyristor region. A highly-doped buried gate region is provided in the p cathode base with the substantially identical configuration for each n cathode emitter regions.

Gate turn-off thyristor

The present invention relates to a buried gate type gate turn-off thyristor. A low-resistance layer which is buried in a cathode base layer has a multiplicity of small bores below a cathode emitter layer. The distance between each pair of adjacent small bores and the thickness of the low-resistance layer are each set so as to be smaller than the carrier diffusion length in an anode base layer. In an on-state, carries flow through the low-resistance layer, thereby allowing the low-resistance layer to become conductive, and thus lowering the on-state voltage. A reduction in the dimension of the small bores lowers the resistance of the low-resistance layer and hence lowers the gate drawing out resistance, so that the interrupting capacity is improved. When gate turn-off thyristor is arranged so as to have an amplifying gate structure, the distance between each pair of adjacent small bores in the amplifying auxiliary thyristor section is set so as to be greater than the carrier diffusion length in the anode base layer. In consequence, the on-state voltage in the auxiliary thyristor section is increased, so that the current selectively flows through the main thyristor section, and the auxiliary thyristor section automatically turns off. Accordingly, when the thyristor is to be turned off, it suffices to turn off the main thyristor section alone.

A semiconductor device includes a semiconductor substrate having at least three semiconductor layers of alternately different conductivity types between a pair of principal surfaces. A pair of main electrodes are kept in low-resistance contact with the outermost ones of the semiconductor layers. A surface-passivation insulating film is provided on an exposed surface of the semiconductor substrate. A resistive material sheet is provided on the insulating film and connected electrically to semiconductor layers having their potentials substantially equal to the main electrodes.

Semiconductor device having high breakdown voltage

In a high-voltage thyristor comprising a semiconductor body having contiguous pnpn four layers, and opposed anode and cathode electrodes and a gate electrode provided for the semiconductor body, one of p-base and n-base regions having an impurity concentration higher than the other has an impurity concentration which is no more than 8.times.10.sup.15 atoms/cm.sup.3 in the vicinity of a junction between the one base region and an adjacent emitter region and which has a gradually decreasing gradient toward the other contiguous base region. The one base region has a sheet resistance of 500 to 1500 ohms/.quadrature.. The realization of a high-voltage, large-diameter and large-current thyristor can be ensured.

High voltage thyristor with optimized doping, thickness, and sheet

A gate turn-off thyristor and a transistor are disclosed, each of which comprises: a semiconductor substrate including at least three semiconductor layers between a pair of principal surfaces, adjacent ones of the semiconductor layers being different in conductivity type from each other, a first one of the semiconductor layers being formed of at least one strip-shaped region with a constant width, a second one of the semiconductor layers being exposed to a first principal surface of the semiconductor substrate together with the strip-shaped region; a first main electrode kept in ohmic contact with the strip-shaped region at the first principal surface; a first control electrode kept in ohmic contact with the second semiconductor layer on one side of the strip-shaped region in the direction of the width thereof and connected directly to a control terminal; a second control electrode kept in ohmic contact with the second semiconductor layer on the other side of the strip-shaped region in the direction of the width thereof and connected to the control terminal through the first control electrode and the resistance of the second semiconductor layer between the first control electrode and the second control electrode; a second main electrode kept in ohmic contact with a second principal surface of the semiconductor substrate; and means provided in the semiconductor substrate for accelerating the spatial biasing of a conductive region to the other side of the strip-shaped region in the direction of the width thereof when a current flowing across the semiconductor substrate is cut off, thereby enlarging the area of safety operation.

Semiconductor device provided with electrically floating control

A semiconductor device such as a transistor or gate turn-off thyristor provided with a control electrode for improving the current cut-off performance, is disclosed in which an emitter layer of a semiconductor substrate is formed of a plurality of strip-shaped regions, a base layer adjacent to the strip-shaped regions is exposed to one principal surface of the semiconductor substrate together with the strip-shaped regions, one main electrode is provided on each strip-shaped region, first and second control electrodes are provided on the base layer, on one and the other sides of each strip-shaped region viewed in the direction of the width thereof, respectively, the other main electrode is provided on the second principal surface of the semiconductor substrate, and a gate terminal is not connected to the first control electrode but connected to the second control electrode, in order to draw out carriers unequally by the first and second control electrodes at a turn-off period. At the initial stage of turn-off action, carriers are drawn out mainly by the second control terminal, and a conductive region contracts so as to be limited to the first control electrode side. At the final stage of turn-off action, carriers are drawn out considerably by the first control electrode, to complete the turn-off action.

Semiconductor device with floating remote gate turn-off means

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Hitachi, Japan

Tsutomu Yatsuo