Patents by Inventor Taketoshi Tanaka

Taketoshi Tanaka 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).

  • Patent number: 9871108
    Abstract: A nitride semiconductor device according to the present invention includes a nitride semiconductor layer having a gate, a source and a drain and a field plate on the nitride semiconductor layer electrically connected to the gate or the source, where when it is assumed that a drain voltage value where the value of COSS is reduced to one half of a value when a drain voltage is 0 V is V1, the dielectric breakdown voltage of the device is V2, a gate length is Lg, a field plate length is Lfp, a shallow acceptor concentration is NA, a deep acceptor concentration is NDA, a vacuum permittivity is ?0 and the relative permittivity of the nitride semiconductor layer is ?, formulas (1) and (2) below are satisfied.
    Type: Grant
    Filed: April 21, 2016
    Date of Patent: January 16, 2018
    Assignee: ROHM CO., LTD.
    Inventors: Taketoshi Tanaka, Norikazu Ito
  • Patent number: 9704982
    Abstract: A semiconductor device comprises a Group III nitride semiconductor lamination structure including a hetero-junction; an insulating layer formed on the Group III nitride semiconductor lamination structure, the insulating layer including a gate opening portion extending to the Group III nitride semiconductor lamination structure; a gate insulating film configured to cover a bottom portion and a side portion of the gate opening portion; a gate electrode formed on the gate insulating film in the gate opening portion; a source electrode and a drain electrode disposed in a spaced-apart relationship with the gate electrode to sandwich the gate electrode and electrically connected to the Group III nitride semiconductor lamination structure; and a conductive layer embedded in the insulating layer between the gate electrode and the drain electrode and insulated from the gate electrode by the gate insulating film, the conductive layer electrically connected to the source electrode.
    Type: Grant
    Filed: January 21, 2016
    Date of Patent: July 11, 2017
    Assignee: ROHM CO., LTD.
    Inventors: Kentaro Chikamatsu, Taketoshi Tanaka, Minoru Akutsu
  • Publication number: 20170104091
    Abstract: A nitride semiconductor device includes: a first nitride semiconductor layer serving as an electron transit layer; a second nitride semiconductor layer formed on the first nitride semiconductor layer, the second nitride semiconductor layer having a band gap greater than that of the first nitride semiconductor layer and serving as an electron supply layer; a third nitride semiconductor layer formed on the second nitride semiconductor layer, the third nitride semiconductor layer having a band gap greater than that of the first nitride semiconductor layer and smaller than that of the second nitride semiconductor layer; and a gate part formed on the third nitride semiconductor layer, wherein the gate part has a fourth nitride semiconductor layer formed on the third nitride semiconductor layer and includes an acceptor type impurity, and a gate electrode formed on the fourth nitride semiconductor layer.
    Type: Application
    Filed: September 22, 2016
    Publication date: April 13, 2017
    Applicant: ROHM CO., LTD.
    Inventor: Taketoshi TANAKA
  • Publication number: 20170104092
    Abstract: A nitride semiconductor device includes: an electron transit layer formed of GaN; an electron supply layer formed on the electron transit layer and to which tensile strain is applied by the electron transit layer, the electron supply layer being formed as an AlxInyGa1-x-yN layer where 0.8?x?1.0 and 0?x+y?1; a passivation film formed on the electron supply layer and formed of SiN, the passivation film having an opening part extending to the electron supply layer; a gate electrode formed on the electron supply layer through a gate insulating film formed within the opening part; and a source electrode and a drain electrode disposed away from the gate electrode to have the gate electrode interposed therebetween, the source electrode and the drain electrode being electrically connected to the electron supply layer. A film thickness of the passivation film is 10 nm or greater.
    Type: Application
    Filed: October 5, 2016
    Publication date: April 13, 2017
    Applicant: ROHM CO., LTD.
    Inventors: Taketoshi TANAKA, Norikazu ITO
  • Publication number: 20170104093
    Abstract: A nitride semiconductor device includes: an electron transit layer including GaxIn1-xN (0<x?1); an electron supply layer formed on the electron transit layer and including AlyIn1-yN (0<y?1); a gate insulating film formed to pass through the electron supply layer to contact the electron transit layer; and a gate electrode facing the electron transit layer with the gate insulating film interposed therebetween, wherein, in the electron transit layer, a portion contacting the gate insulating film and a portion contacting the electron transit layer are flush with each other.
    Type: Application
    Filed: October 6, 2016
    Publication date: April 13, 2017
    Applicant: ROHM CO., LTD.
    Inventors: Shinya TAKADO, Minoru AKUTSU, Taketoshi TANAKA, Norikazu ITO
  • Publication number: 20170047410
    Abstract: A nitride semiconductor device includes: a nitride semiconductor layer; a gate electrode finger having at least one end portion, and extending along a surface of the nitride semiconductor layer; and a drain electrode finger having at least one end portion on the same side as that of the one end portion of the gate electrode finger, and extending along the gate electrode finger, wherein the one end portion of the drain electrode finger protrudes relative to the one end portion of the gate electrode finger.
    Type: Application
    Filed: August 9, 2016
    Publication date: February 16, 2017
    Applicant: ROHM CO., LTD.
    Inventor: Taketoshi TANAKA
  • Publication number: 20170047412
    Abstract: A nitride semiconductor device according to the present invention includes a nitride semiconductor layer including an electron transit layer and an electron supply layer which is in contact with the electron transit layer and which has a composition different from that of the electron transit layer, a gate electrode on the nitride semiconductor layer and a gate insulating film between the gate electrode and the nitride semiconductor layer. A region whose depth is 250 nm from an interface between the gate insulating film and the gate electrode includes a region which has a deep acceptor concentration equal to or more than 1.0×1016 cm?3.
    Type: Application
    Filed: August 9, 2016
    Publication date: February 16, 2017
    Applicant: ROHM CO., LTD.
    Inventors: Taketoshi TANAKA, Minoru AKUTSU, Norikazu ITO
  • Publication number: 20160315180
    Abstract: A nitride semiconductor device according to the present invention includes a nitride semiconductor layer having a gate, a source and a drain and a field plate on the nitride semiconductor layer electrically connected to the gate or the source, where when it is assumed that a drain voltage value where the value of COSS is reduced to one half of a value when a drain voltage is 0 V is V1, the dielectric breakdown voltage of the device is V2, a gate length is Lg, a field plate length is Lfp, a shallow acceptor concentration is NA, a deep acceptor concentration is NDA, a vacuum permittivity is ?0 and the relative permittivity of the nitride semiconductor layer is ?, formulas (1) and (2) below are satisfied.
    Type: Application
    Filed: April 21, 2016
    Publication date: October 27, 2016
    Applicant: ROHM CO., LTD.
    Inventors: Taketoshi TANAKA, Norikazu ITO
  • Publication number: 20160282289
    Abstract: A nitride semiconductor device includes: a conductive substrate; a first nitride semiconductor which is formed on the substrate and contains Ga or Al; an electron supply layer which is formed in contact with the first nitride semiconductor layer and is made of a second nitride semiconductor having a different composition from that of the first nitride semiconductor layer in an interface between the electron supply layer and the first nitride semiconductor layer; and a source, a gate and a drain or an anode and a cathode which are formed on a front surface of the substrate, wherein the first nitride semiconductor layer has a thickness of w or more, a deep acceptor concentration distribution NDA(z) and a shallow acceptor concentration distribution NA(z), which satisfy the following equations (1) to (3): ? 0 w ? { E c ? ( x ) - ? 0 w ? q ? ( N DA ? ( z ) + N A ? ( z ) ) ? 0 ? ? } ? ? ? z ? ? V b ( 1 ) E c ? ( x ) = 3.
    Type: Application
    Filed: March 24, 2016
    Publication date: September 29, 2016
    Applicant: ROHM CO., LTD.
    Inventor: Taketoshi TANAKA
  • Publication number: 20160218203
    Abstract: A semiconductor device comprises a Group III nitride semiconductor lamination structure including a hetero-junction; an insulating layer formed on the Group III nitride semiconductor lamination structure, the insulating layer including a gate opening portion extending to the Group III nitride semiconductor lamination structure; a gate insulating film configured to cover a bottom portion and a side portion of the gate opening portion; a gate electrode formed on the gate insulating film in the gate opening portion; a source electrode and a drain electrode disposed in a spaced-apart relationship with the gate electrode to sandwich the gate electrode and electrically connected to the Group III nitride semiconductor lamination structure; and a conductive layer embedded in the insulating layer between the gate electrode and the drain electrode and insulated from the gate electrode by the gate insulating film, the conductive layer electrically connected to the source electrode.
    Type: Application
    Filed: January 21, 2016
    Publication date: July 28, 2016
    Applicant: ROHM CO., LTD.
    Inventors: Kentaro CHIKAMATSU, Taketoshi TANAKA, Minoru AKUTSU
  • Publication number: 20150155684
    Abstract: A method for manufacturing a semiconductor laser device includes preparing an original substrate having a plurality of semiconductor laser device regions arrayed in a matrix, and a plurality of ridges formed in stripes so as to pass through each of the plurality of semiconductor laser device regions that are aligned in one direction. A scribing process is applied to the original substrate along cutting lines set along boundaries of the plurality of semiconductor laser device regions from a rear surface at an opposite side of a top surface at which the ridges are formed. A blade is applied to the original substrate along each cutting line from the top surface of the original substrate for dividing the original substrate along the cutting line.
    Type: Application
    Filed: February 10, 2015
    Publication date: June 4, 2015
    Inventors: Junichi KASHIWAGI, Kuniyoshi OKAMOTO, Taketoshi TANAKA, Masashi KUBOTA
  • Publication number: 20120213242
    Abstract: A semiconductor laser device includes a nitride semiconductor laminate structure including an n-type clad layer, an n-type guide layer formed on the n-type clad layer, a light emitting layer formed on the n-type guide layer and a p-type semiconductor layer formed on the light emitting layer. The nitride semiconductor laminate structure does not include a p-type semiconductor clad layer. The semiconductor laser device further includes an upper clad layer formed on the p-type semiconductor layer. The upper clad layer includes a first conductive film made of an indium oxide-based material and a second conductive film formed on the first conductive film and made of a zinc oxide-based material, a gallium oxide-based material or a tin oxide-based material.
    Type: Application
    Filed: February 16, 2012
    Publication date: August 23, 2012
    Applicant: ROHM CO., LTD.
    Inventors: Taketoshi Tanaka, Shinya Takado, Junichi Kashiwagi, Masashi Yamamoto, Ken Nakahara
  • Publication number: 20120189029
    Abstract: A semiconductor laser device includes a semiconductor laminate structure that includes a light emitting layer that contains In, a p-type guide layer disposed at one side of the light emitting layer, an n-type guide layer disposed at another side of the light emitting layer; a p-type clad layer disposed at an opposite side of the p-type guide layer to the light emitting layer, and an n-type clad layer disposed at an opposite side of the n-type guide layer to the light emitting layer. The semiconductor laminate structure includes a rectilinear waveguide formed parallel to a projection vector of a c-axis onto the crystal growth surface, and a pair of laser resonance surfaces formed of cleavage planes perpendicular to the projection vector.
    Type: Application
    Filed: December 6, 2011
    Publication date: July 26, 2012
    Applicant: ROHM CO., LTD.
    Inventors: Junichi Kashiwagi, Kuniyoshi Okamoto, Taketoshi Tanaka, Masashi Kubota
  • Patent number: 8189640
    Abstract: Provided is a laser light emitting device that has light sources of multiple wavelengths including an oscillation wavelength in a green region and the like, and that can be miniaturized. A metal wiring 4 is formed on a supporting substrate 5. A green LD 1 and a red LD 2 are bonded to the metal wiring 4. Each of the green LD 1 and the red LD 2 is a laser diode element formed of a semiconductor having a layered structure. One of a positive electrode and a negative electrode of the element is bonded to the metal wiring 4, and the other electrode is connected to a lead wire 6 or a lead wire 7. The green LD 1 is formed of a GaN-based semiconductor laser diode having a nonpolar plane or a semipolar plane as a main surface for crystal growth. The red LD 2 is formed of an AlInGaP-based semiconductor laser diode.
    Type: Grant
    Filed: May 21, 2008
    Date of Patent: May 29, 2012
    Assignee: Rohm Co., Ltd.
    Inventors: Taketoshi Tanaka, Kuniyoshi Okamoto, Hiroaki Ohta
  • Patent number: 8013356
    Abstract: A semiconductor light emitting device has a device body made of a group III nitride semiconductor having a major surface defined by a nonpolar plane. In the device body, a contact portion with an n-type electrode includes a crystal plane different from the major surface. For example, the contact portion may include a corrugated surface. More specifically, the contact portion may include a region having a plurality of protrusions parallel to a polar plane formed in a striped manner.
    Type: Grant
    Filed: September 26, 2008
    Date of Patent: September 6, 2011
    Assignee: Rohm Co., Ltd.
    Inventors: Taketoshi Tanaka, Kuniyoshi Okamoto
  • Patent number: 7869482
    Abstract: A semiconductor laser device is made of a group III nitride semiconductor having a major growth surface defined by a nonpolar plane or a semipolar plane. The semiconductor laser device includes a cavity having an active layer containing In and distributed Bragg reflectors coating both cavity end faces of the cavity respectively. In each of the distributed Bragg reflectors, a central wavelength ?c of a reflectance spectrum satisfies the relation ?SP?10 nm??c??SP+10 nm with respect to an emission peak wavelength ?SP of spontaneous emission in the active layer.
    Type: Grant
    Filed: April 2, 2009
    Date of Patent: January 11, 2011
    Assignee: Rohm Co., Ltd.
    Inventors: Masashi Kubota, Kuniyoshi Okamoto, Taketoshi Tanaka
  • Publication number: 20100195687
    Abstract: A semiconductor laser device has a semiconductor laser diode structure made of group III nitride semiconductors having major growth surfaces defined by nonpolar planes or semipolar planes. The semiconductor laser diode structure includes a p-type cladding layer and an n-type cladding layer, a p-type guide layer and an n-type guide layer held between the p-type cladding layer and the n-type cladding layer, and an active layer containing In held between the p-type guide layer and the n-type guide layer. The In compositions in the p-type guide layer and the n-type guide layer are increased as approaching the active layer respectively. Each of the p-type guide layer and the n-type guide layer may have a plurality of InxGa1-xN layers (0?x?1). In this case, the plurality of InxGa1-xN layers may be stacked in such order that the In compositions therein are increased as approaching the active layer.
    Type: Application
    Filed: February 1, 2010
    Publication date: August 5, 2010
    Applicant: ROHM CO., LTD.
    Inventors: Kuniyoshi Okamoto, Masashi Kubota, Taketoshi Tanaka, Junichi Kashiwagi, Yoshinori Tanaka
  • Publication number: 20100189155
    Abstract: Provided is a laser light emitting device that has light sources of multiple wavelengths including an oscillation wavelength in a green region and the like, and that can be miniaturized. A metal wiring 4 is formed on a supporting substrate 5. A green LD 1 and a red LD 2 are bonded to the metal wiring 4. Each of the green LD 1 and the red LD 2 is a laser diode element formed of a semiconductor having a layered structure. One of a positive electrode and a negative electrode of the element is bonded to the metal wiring 4, and the other electrode is connected to a lead wire 6 or a lead wire 7. The green LD 1 is formed of a GaN-based semiconductor laser diode having a nonpolar plane or a semipolar plane as a main surface for crystal growth. The red LD 2 is formed of an AlInGaP-based semiconductor laser diode.
    Type: Application
    Filed: May 21, 2008
    Publication date: July 29, 2010
    Inventors: Taketoshi Tanaka, Kuniyoshi Okamoto, Hiroaki Ohta
  • Publication number: 20090252191
    Abstract: A semiconductor laser device is made of a group III nitride semiconductor having a major growth surface defined by a nonpolar plane or a semipolar plane. The semiconductor laser device includes a cavity having an active layer containing In and distributed Bragg reflectors coating both cavity end faces of the cavity respectively. In each of the distributed Bragg reflectors, a central wavelength ?c of a reflectance spectrum satisfies the relation ?SP?10 nm??c??SP+10 nm with respect to an emission peak wavelength ?SP of spontaneous emission in the active layer.
    Type: Application
    Filed: April 2, 2009
    Publication date: October 8, 2009
    Applicant: ROHM CO., LTD.
    Inventors: Masashi Kubota, Kuniyoshi Okamoto, Taketoshi Tanaka
  • Publication number: 20090238227
    Abstract: A semiconductor light emitting device is made of a group III nitride semiconductor having a major growth surface defined by a nonpolar plane or a semipolar plane, and has a quantum well layer containing In in a light emitting layer. A strain compensation layer made of a group III nitride semiconductor containing Al and having a lattice constant smaller than the lattice constant of the quantum well layer in a strain-free state is interposed in the light emitting layer of a quantum well structure having the quantum well layer and a barrier layer or in an adjacent layer adjacent to the light emitting layer.
    Type: Application
    Filed: March 4, 2009
    Publication date: September 24, 2009
    Applicant: ROHM CO., LTD.
    Inventors: Masashi Kubota, Kuniyoshi Okamoto, Taketoshi Tanaka, Yoshinori Tanaka