Mitsubishi Denki Kabushiki Kaisha

Mitsubishi Electric Corporation

Yasunori Tokuda

Yuji Abe

Toshiyuki Oishi

Naruhisa Miura

Katsuomi Shiozawa

Taisuke Furukawa

Takumi Nakahata

Kohei Sugihara

Kenzo Fujiwara

Shigemitsu Maruno

Satoshi Yamakawa

Kyozo Kanamoto

Yoichiro Tarui

Hiroshi Kurokawa

Kenichi Ohtsuka

Noriaki Tsukada

Hitoshi Sakuma

Kyosuke Kuramoto

Yosuke Suzuki

Takuma Nanjo

Yoshinori Nomura

Teruhito Matsui

Keisuke Kojima

Muneyoshi Suita

Yasutaka Nishioka

Shigetoshi Nara

Tatsuo Omori

The objective of the present invention is to provide a semiconductor device of a hetero-junction field effect transistor that is capable of obtaining a high output and a high breakdown voltage and a manufacturing method of the same. The present invention is a semiconductor device of a hetero-junction field effect transistor provided with an AlGaN channel layer with a composition ratio of Al being x (0&#x3c;x&#x3c;1) formed on a substrate, an AlGaN barrier layer with a composition of Al being y (0&#x3c;y&#x2266;1) formed on the channel layer, and source/drain electrodes and a gate electrode formed on the barrier layer, wherein the composition ratio y is larger than the composition ratio x.

Nitride semiconductor heterojunction field effect transistor having wide band gap barrier layer that includes high concentration impurity region

A nitride semiconductor device with a p electrode having no resistance between itself and other electrodes, and a method of manufacturing the same are provided. A p electrode is formed of a first Pd film, a Ta film, and a second Pd film, which is an antioxidant film for preventing oxidation of the Ta film, and on a p-type contact layer of a nitride semiconductor. On the second Pd film, a pad electrode is formed. The second Pd film as an antioxidant film is formed on the entire upper surface of the Ta film which forms the p electrode, to prevent oxidation of the Ta film. This inhibits the resistance between the p electrode and the pad electrode, thereby preventing a failure in contact between the p electrode and the pad electrode and providing the low-resistance p electrode.

Nitride semiconductor device including an electrode in ohmic contact with a P-type nitride semiconductor contact layer

A nitride semiconductor device with a p electrode having no resistance between itself and other electrodes, and a method of manufacturing the same are provided. A p electrode is formed of a first Pd film, a Ta film, and a second Pd film, and on a p-type contact layer of a nitride semiconductor. On the second Pd film, a pad electrode is formed. The second Pd film is formed on the entire upper surface of the Ta film which forms part of the p electrode, and serves as an antioxidant film that prevents oxidation of the Ta film. Preventing oxidation of the Ta film, the second Pd film can reduce the resistance that may exist between the p electrode and the pad electrode, thereby preventing a failure in contact between the p electrode and the pad electrode and providing the p electrode with low resistance.

Nitride semiconductor device

A method of manufacturing a semiconductor device provides a semiconductor device with a gallium-nitride-based semiconductor structure that allows long-term stable operation without degradation in device performance. After formation of an insulation film on a surface other than on a ridge surface, an oxygen-containing gas such as O, O, NO, NO, or NOis supplied to oxidize a p-type GaN contact layer from the surface and to thereby form an oxide film on the surface of the p-type GaN contact layer. Then, a p-type electrode that establishes contact with the p-type GaN contact layer is formed by evaporation or sputtering on the oxide film and on the insulation film. Heat treatment is subsequently performed at temperatures between 400 and 700&#xb0; C. in an atmosphere containing a nitrogen-containing gas such as Nor NHor an inert gas such as Ar or He.

Method of manufacturing semiconductor device including gallium-nitride semiconductor structure and a palladium contact

A polysilicon nitride film is formed to cover a polysilicon gate. By heat treatment of the silicon nitride film in an oxygen atmosphere, a silicon oxinitride film is formed. By anisotropically etching the silicon oxinitride film and the silicon nitride film, a sidewall insulating film is formed. By epitaxial growth, selective silicon films of a prescribed film thickness are formed on source and drain regions. During this period, silicon islands are not deposited on the surface of sidewall insulating film. Consequently, a semiconductor device including a transistor of a superior electrical insulation can be obtained.

Semiconductor device and manufacturing method thereof

A method of producing a semiconductor device includes forming a gate electrode on a channel region on a surface of a semiconductor region of a semiconductor substrate, the channel region having a depth in the semiconductor substrate; forming a first pair of side wall spacers on opposite sides of the gate electrode; forming elevated semiconductor layers, each elevated semiconductor layer being elevated relative to the channel region, on regions outside of the pair of side wall spacers and in which source and drain regions of a first conductivity type are to be formed; removing the pair of first side wall spacers; and forming a pair of pocket injection regions of a second conductivity type by introducing, after the side wall spacers are removed, a dopant impurity producing the second conductivity type deeper in the semiconductor substrate than a region where the side wall spacers were formed, the pair of pocket injection regions respectively covering only a neighborhood of respective side surface parts of the channel region, where the source and drain regions are to be formed, forming respective pn junctions only between the neighborhood of the side surface parts and the pocket injection regions.

Method of making field effect transistor in which the increase of parasitic capacitance is restrained by scale reduction

Source and drain regions include regions of an epitaxial silicon film on the surface of the substrate and regions in the substrate. The depth of junctions of the source and drain regions is identical to or shallower than the depth of junctions of extension regions. As a result, even if the thickness of the side wall layer is reduced, since the depletion layer of the extension regions with lower impurity concentration compared with the source and drain regions is predominant, the short channel effect has a smaller effect.

Semiconductor device with sidewall spacers and elevated source/drain region

In making a field effect transistor, a dummy gate electrode is formed before a gate electrode is formed. Extension regions, a side wall silicon nitride film, source/drain regions, a silicon oxide film, and other elements are formed with respect to the dummy gate electrode. The dummy gate electrode is removed, and a part of the extension regions diffused into a region immediately under the dummy gate electrode is removed. The removed part is filled with silicon selection epitaxial film. Thereafter, the intended gate electrode is formed. This production method produces a field effect transistor that prevents deterioration of electrical characteristics caused by the short channel effect and parasitic resistance.

Semiconductor device

A major object of the present invention is to provide an improved semiconductor device so as to be able to reduce gate electric field concentration at a channel edge, suppress decrease in the threshold during MOSFET operation and reduce the leakage current. A gate insulation film is formed on a semiconductor substrate. A gate electrode is formed on the semiconductor substrate with the gate insulation film therebetween. The dielectric constant of the gate insulation film is not uniform in the surface.

Source/drain diffusion regions are formed on the silicon substrate such that the source/drain diffusion regions sandwich a gate electrode from both sides on the silicon substrate. Sidewall oxide films are formed, one on each side surface of the gate electrode. Recessed portions are formed in the extension portions E beneath the sidewall oxide films. Source/drain electrodes are formed to fill the recessed portions. Thus, the sheet resistance of the respective regions including a pair of source/drain diffusion regions and source/drain electrodes is reduced, and a semiconductor device with a field-effect transistor having an improved current drivability is obtained.

Semiconductor device having reduced sheet resistance of source/drain regions

Method of manufacturing semiconductor device having sidewall portions removed

According to the inventive method of fabricating a semiconductor device, a silicon substrate is exposed to an oxygen atmosphere of 600&deg; C. to 900&deg; C., for forming silicon oxide films on surfaces of epitaxial silicon layers and those of silicon fragments. Thus, a method of fabricating a semiconductor device capable of preventing electrodes thereof from shorting can be provided.

Method of fabricating semiconductor device

A light transmission circuit 20 is biased to one optical bistable region of its multistable characteristic by a bias light from a light source 29. The bias light is superimposed by plural control pulse lights, and the superimposed light is irradiated. If the light intensity of the bias light exceeds a predetermined turning point according to the light intensity of the control pulse light, the state of multiple quantum well layers 4 and 24 are changed. Then, the light transmission state of the light transmission circuit 20 changes. Hereby, after the control pulse light disappeared, the bias light is detected by a light-receiving device 30 in a different transmission state from the prior state. And, the transmission state returns to the original state by selecting suitable light intensities of the control pulse lights to be superimposed. Therefore the light transmission circuit 20 can be switched reversibly.

Optical switching apparatus

According to the present invention, there is provided a nonlinear optical element including a p-i-n type photodiode (i layer is a light absorbing layer) provided with a barrier layer preventing the going-through of a majority carrier. In the nonlinear optical element of the present invention, since the charges are accumulated with the stop of carrier moving, there occur a deformation in energy band and change in internal electric field. Optical bistability can be attained even without an external circuit. Further, with a plurality of incident light, only one element can exhibit optical bistability therefor because there is no need to dispose an external circuit. According to a method of the present invention, it is possible to control bistability for one light by overlapping another light input to a carrier diffusing region generated by the one light.

Nonlinear optical element and method of using the same

A method of selective light detection uses an optical multi-stable device selectively exhibiting a variety of optical multi-stable characteristics for incident light wavelengths or intensities. The device includes an optically serial connection of two optical bistable elements. Each of the optical bistable elements includes a photodiode having a light absorbing layer including a quantum well structure. The photodiodes are reverse biased by respective voltage sources through respective series resistors so that an optical bistable characteristic for incident light wavelength or intensity is achieved for each photodiode. The characteristic of the second photodiode includes four stable photocurrents at respective wavelengths.

Growing community of inventors

Tokyo, Japan

Yasunori Tokuda