Patents by Inventor Shinichi Kohda
Shinichi Kohda has filed for patents to protect the following inventions. This listing includes patent applications that are pending as well as patents that have already been granted by the United States Patent and Trademark Office (USPTO).
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Patent number: 7939429Abstract: A method of manufacturing a nitride semiconductor device includes the steps of: forming a division guide groove by applying a laser beam having a wavelength and energy density causing multiphoton absorption to a surface of a substrate having a group III nitride semiconductor layer grown on a major surface thereof; removing deposits from the surface of the substrate by applying a laser beam having the wavelength to the surface of the substrate at energy density causing substantially no multiphoton absorption on the substrate; and dividing the substrate along the division guide groove.Type: GrantFiled: July 23, 2008Date of Patent: May 10, 2011Assignee: Rohm Co., Ltd.Inventor: Shinichi Kohda
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Publication number: 20110096805Abstract: A nitride semiconductor laser device is formed by growing a group III nitride semiconductor multilayer structure on a substrate. The group III nitride semiconductor multilayer structure has a laser resonator including an n-type semiconductor layer, a p-type semiconductor layer and a light emitting layer held between the n-type semiconductor layer and the p-type semiconductor layer. The laser resonator is arranged to be offset from the center with respect to a device width direction orthogonal to a resonator direction toward one side edge of the device. A wire bonding region having a width of not less than twice the diameter of an electrode wire to be bonded to the device is formed between the laser resonator and the other side edge of the device.Type: ApplicationFiled: December 30, 2010Publication date: April 28, 2011Applicant: ROHM CO., LTD.Inventors: Shinichi KOHDA, Yuji Ishida
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Publication number: 20110085579Abstract: A nitride semiconductor laser device is formed by growing a group III nitride semiconductor multilayer structure on a substrate containing no Al. The group III nitride semiconductor multilayer structure forms a structure including an n-type semiconductor layer, a p-type semiconductor layer, and a light emitting layer held between the n-type semiconductor layer and the p-type semiconductor layer. The n-type semiconductor layer includes an n-type cladding layer containing Al and an n-type guide layer having a smaller band gap than the n-type cladding layer. The p-type semiconductor layer includes a p-type cladding layer containing Al and a p-type guide layer having a smaller band gap than the p-type cladding layer. A removal region is formed by partially removing the layers containing Al in the group III nitride semiconductor multilayer structure from the substrate.Type: ApplicationFiled: December 17, 2010Publication date: April 14, 2011Applicant: ROHM CO., LTD.Inventor: Shinichi KOHDA
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Patent number: 7885303Abstract: A nitride semiconductor laser device is formed by growing a group III nitride semiconductor multilayer structure on a substrate. The group III nitride semiconductor multilayer structure has a laser resonator including an n-type semiconductor layer, a p-type semiconductor layer and a light emitting layer held between the n-type semiconductor layer and the p-type semiconductor layer. The laser resonator is arranged to be offset from the center with respect to a device width direction orthogonal to a resonator direction toward one side edge of the device. A wire bonding region having a width of not less than twice the diameter of an electrode wire to be bonded to the device is formed between the laser resonator and the other side edge of the device.Type: GrantFiled: December 26, 2008Date of Patent: February 8, 2011Assignee: Rohm Co., Ltd.Inventors: Shinichi Kohda, Yuji Ishida
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Patent number: 7876798Abstract: A nitride semiconductor laser device is formed by growing a group III nitride semiconductor multilayer structure on a substrate containing no Al. The group III nitride semiconductor multilayer structure forms a structure including an n-type semiconductor layer, a p-type semiconductor layer, and a light emitting layer held between the n-type semiconductor layer and the p-type semiconductor layer. The n-type semiconductor layer includes an n-type cladding layer containing Al and an n-type guide layer having a smaller band gap than the n-type cladding layer. The p-type semiconductor layer includes a p-type cladding layer containing Al and a p-type guide layer having a smaller band gap than the p-type cladding layer. A removal region is formed by partially removing the layers containing Al in the group III nitride semiconductor multilayer structure from the substrate.Type: GrantFiled: December 26, 2008Date of Patent: January 25, 2011Assignee: Rohm Co., Ltd.Inventor: Shinichi Kohda
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Patent number: 7792171Abstract: A nitride semiconductor laser device has a group III nitride semiconductor multilayer structure. The group III nitride semiconductor multilayer structure includes an n-type semiconductor layer, a p-type semiconductor layer and a light emitting layer held between the n-type semiconductor layer and the p-type semiconductor layer, and the p-type semiconductor layer is formed by successively stacking a p-side guide layer, a p-type electron blocking layer in contact with the p-side guide layer and a p-type cladding layer in contact with the p-type electron blocking layer from the side closer to the light emitting layer. The p-side guide layer is formed by stacking a layer made of a group III nitride semiconductor containing Al and a layer made of a group III nitride semiconductor containing no Al.Type: GrantFiled: November 12, 2008Date of Patent: September 7, 2010Assignee: Rohm Co., Ltd.Inventors: Shinichi Kohda, Daisuke Nakagawa
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Publication number: 20100008391Abstract: A nitride based semiconductor device includes: an n-type cladding layer; an n-type GaN based guide layer placed on the n-type cladding layer; an active layer placed on the n-type GaN based guide layer; a p-type GaN based guide layer placed on the active layer; an electron block layer placed on the p-type GaN based guide layer; a stress relaxation layer placed on the electron block layer; and a p-type cladding layer placed on the stress relaxation layer, and the nitride based semiconductor device alleviates the stress occurred under the influence of the electron block layer, does not affect light distribution by the electron block layer, reduces threshold current, can suppress the degradation of reliability, can suppress degradation of the emitting end surface of the laser beam, can improve the far field pattern, and is long lasting, and fabrication method of the device is also provided.Type: ApplicationFiled: March 4, 2009Publication date: January 14, 2010Applicant: ROHM CO., LTD.Inventors: Daisuke Nakagawa, Yoshinori Tanaka, Masahiro Murayama, Takao Fujimori, Shinichi Kohda
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Publication number: 20090230514Abstract: A method of manufacturing a nitride semiconductor device includes the steps of: growing a group III nitride semiconductor layer on a substrate; forming a processed region in the substrate with a laser beam; and reducing the thickness of the substrate thereby spontaneously dividing the substrate from the processed region by the internal stress of the substrate. The substrate may be a sapphire substrate or an SiC substrate.Type: ApplicationFiled: July 25, 2008Publication date: September 17, 2009Applicant: ROHM CO., LTD.Inventor: Shinichi Kohda
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Patent number: 7566639Abstract: Processed traces are formed on at least a part of intended cutting lines A along which a wafer (10) where a nitride semiconductor lamination portion (6) is formed on a GaN based substrate (1) is divided into chips, by irradiating with a laser beam LB having a wavelength which is longer than the band gap wavelength of the GaN based substrate 1 and an electrical field intensity which causes a multiple photons absorption, while adjusting the focal point to a constant depth d within the GaN based substrate (1) from the back surface of the wafer. After that, the wafer (10) is divided into chips along cutting starting points (12) which are formed in the vicinity of the processed traces by hitting with an impact. As a result, the wafer can be easily divided into chips, and in particular, end faces of a resonator can be formed with cleavage planes when an LD is formed.Type: GrantFiled: September 15, 2006Date of Patent: July 28, 2009Assignee: Rohm Co., Ltd.Inventor: Shinichi Kohda
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Publication number: 20090180505Abstract: A nitride semiconductor laser device is formed by growing a group III nitride semiconductor multilayer structure on a substrate. The group III nitride semiconductor multilayer structure has a laser resonator including an n-type semiconductor layer, a p-type semiconductor layer and a light emitting layer held between the n-type semiconductor layer and the p-type semiconductor layer. The laser resonator is arranged to be offset from the center with respect to a device width direction orthogonal to a resonator direction toward one side edge of the device. A wire bonding region having a width of not less than twice the diameter of an electrode wire to be bonded to the device is formed between the laser resonator and the other side edge of the device.Type: ApplicationFiled: December 26, 2008Publication date: July 16, 2009Applicant: ROHM CO., LTD.Inventors: Shinichi KOHDA, Yuji ISHIDA
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Publication number: 20090175305Abstract: A nitride semiconductor laser device is formed by growing a group III nitride semiconductor multilayer structure on a substrate containing no Al. The group III nitride semiconductor multilayer structure forms a structure including an n-type semiconductor layer, a p-type semiconductor layer, and a light emitting layer held between the n-type semiconductor layer and the p-type semiconductor layer. The n-type semiconductor layer includes an n-type cladding layer containing Al and an n-type guide layer having a smaller band gap than the n-type cladding layer. The p-type semiconductor layer includes a p-type cladding layer containing Al and a p-type guide layer having a smaller band gap than the p-type cladding layer. A removal region is formed by partially removing the layers containing Al in the group III nitride semiconductor multilayer structure from the substrate.Type: ApplicationFiled: December 26, 2008Publication date: July 9, 2009Applicant: ROHM CO., LTD.Inventor: Shinichi Kohda
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Patent number: 7550757Abstract: A back-surface-electrode type semiconductor laser of GaN-based compound has low electric resistance and high light emitting efficiency, and includes negative electrodes made of Al having a contact surface that contacts with the n-type GaN substrate. The back-surface-electrode type semiconductor laser has GaN-based compound layers laminated on an n-type GaN substrate with an area of reversal of polarity with low electric resistance and a negative electrode is disposed on the side opposite to the side of GaN-based compound layer of the GaN substrate so as to come in contact with the area of reversal of polarity.Type: GrantFiled: November 17, 2006Date of Patent: June 23, 2009Assignee: Rohm Co., Ltd.Inventors: Hiroaki Ohta, Shinichi Kohda
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Publication number: 20090148975Abstract: A method of manufacturing a nitride semiconductor device includes: a working region forming step of forming a working region in a group III nitride semiconductor substrate by converging a laser beam having a wavelength of 500 nm to 700 nm in the group III nitride semiconductor substrate and by scanning a convergent point of the laser beam in a prescribed scanning direction in the interior of the group III nitride semiconductor substrate; and a dividing step of dividing the group III nitride semiconductor substrate by generating a crack from the working region without processing a surface of the group III nitride semiconductor substrate.Type: ApplicationFiled: March 26, 2008Publication date: June 11, 2009Applicant: ROHM CO., LTD.Inventor: Shinichi Kohda
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Publication number: 20090141765Abstract: A nitride semiconductor laser device has a group III nitride semiconductor multilayer structure. The group III nitride semiconductor multilayer structure includes an n-type semiconductor layer, a p-type semiconductor layer and a light emitting layer held between the n-type semiconductor layer and the p-type semiconductor layer, and the p-type semiconductor layer is formed by successively stacking a p-side guide layer, a p-type electron blocking layer in contact with the p-side guide layer and a p-type cladding layer in contact with the p-type electron blocking layer from the side closer to the light emitting layer. The p-side guide layer is formed by stacking a layer made of a group III nitride semiconductor containing Al and a layer made of a group III nitride semiconductor containing no Al.Type: ApplicationFiled: November 12, 2008Publication date: June 4, 2009Applicant: ROHM CO., LTD.Inventors: Shinichi KOHDA, Daisuke NAKAGAWA
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Publication number: 20090101927Abstract: A method of manufacturing a semiconductor light emitting device employs a substrate formed by successively stacking an n-type semiconductor layered portion including an AlGaN layer, a light emitting layer containing In and a p-type semiconductor layered portion on a group III nitride semiconductor substrate having a larger lattice constant than AlGaN. This method includes the steps of selectively etching the substrate from the side of the p-type semiconductor layered portion along a cutting line to expose the AlGaN layer along the cutting line, forming a division guide groove along the cutting line on the exposed AlGaN layer, and dividing the substrate along the division guide groove.Type: ApplicationFiled: September 2, 2008Publication date: April 23, 2009Applicant: ROHM CO.,LTD.Inventor: Shinichi Kohda
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Publication number: 20090046754Abstract: A method of manufacturing a nitride semiconductor device includes the steps of: forming a division guide groove by applying a laser beam having a wavelength and energy density causing multiphoton absorption to a surface of a substrate having a group III nitride semiconductor layer grown on a major surface thereof; removing deposits from the surface of the substrate by applying a laser beam having the wavelength to the surface of the substrate at energy density causing substantially no multiphoton absorption on the substrate; and dividing the substrate along the division guide groove.Type: ApplicationFiled: July 23, 2008Publication date: February 19, 2009Applicant: ROHM CO., LTD.Inventor: Shinichi Kohda
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Publication number: 20090045486Abstract: A method of manufacturing a nitride semiconductor device includes the steps of: forming a mask of a pattern selectively covering a cutting line on a first major surface of a substrate; forming group III nitride semiconductor layers exposing the mask provided on the cutting line by selectively growing a group III nitride semiconductor from exposed portions of the first major surface of the substrate; forming a division guide groove on the substrate along the cutting line; and dividing the substrate along the division guide groove. The step of forming the division guide groove may be a step of forming the division guide groove by laser processing.Type: ApplicationFiled: July 25, 2008Publication date: February 19, 2009Applicant: ROHM CO., LTD.Inventor: Shinichi Kohda
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Publication number: 20080258166Abstract: There is provided a semiconductor light emitting semiconductor device including an n-side electrode which has a structure capable of stably suppressing the contact resistance between the n-side electrode and a nitride semiconductor layer. Further, there is provided a light emitting device and a manufacturing method wherein an ohmic contact between the n-side electrode and the nitride semiconductor layer can be obtained by a simple manufacturing process, and the n-side electrode has an Au layer on a top surface to facilitate wire bonding. Semiconductor layers (2-8) to form a light emitting layer are laminated on a surface of a substrate (1) made of, for example, a sapphire (Al2O3 single crystal) or the like and a p-side electrode (10) is formed on the surface thereof thorough a light transmitting conductive layer (9). An n-side electrode (11) is formed on an exposed surface of an n-type layer (4), exposed by removing a part of the semiconductor layers (4-8) by etching.Type: ApplicationFiled: May 10, 2005Publication date: October 23, 2008Inventors: Mitsuhiko Sakai, Shinichi Kohda, Masayuki Sonobe, Ken Nakahara
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Patent number: 7256416Abstract: Causing the growth of a GaN material with respect to a sapphire substrate using a conventional technique is inevitably followed by the occurrence of dislocations. Using a mask layer results in that the dislocations laterally flow. However, since the GaN crystal collides with a semiconductor layer that laterally grew from an adjacent region, perfect elimination of the dislocations is impossible. In view thereof, the invention is intended to provide a nitride compound-based semiconductor light emitting device which is based on using semiconductor layers that have been formed in a state of the dislocations' being less existent therein and which therefore has excellent property.Type: GrantFiled: August 12, 2004Date of Patent: August 14, 2007Assignee: Rohm Co., Ltd.Inventor: Shinichi Kohda
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Publication number: 20070131939Abstract: A semiconductor lamination portion (9) including an active layer (4) is formed on a substrate (1). The semiconductor lamination portion is made of, for example, a nitride material having a cleavage plane not parallel to a cleavage plane of the substrate (1) and has a resonance cavity end faces (6) from which a laser beam is emitted. And a metal layer portion (5) is provided between the substrate and the active layer in a vicinity of the resonance cavity end faces. As a result, even if a crack is caused between the substrate and the semiconductor lamination portion, an extension of the crack stops at the metal layer portion, thereby the crack does not reach to the active layer at the resonance cavity end faces, and the cleavage plane free from any crack can be obtained at the resonance cavity end faces. Therefore, as an absorption loss at the resonance cavity end faces is reduced, the semiconductor laser which is driven with low operating current and has high reliability can be obtained.Type: ApplicationFiled: November 12, 2004Publication date: June 14, 2007Inventor: Shinichi Kohda