Patents by Inventor Isao Yokokawa

Isao Yokokawa 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: 8956951
    Abstract: A method for manufacturing an SOI wafer includes performing a flattening heat treatment on an SOI wafer under an atmosphere containing an argon gas, in which conditions of SOI wafer preparation are set so that a thickness of an SOI layer of the SOI wafer to be subjected to the flattening heat treatment is 1.4 or more times thicker than that of a BOX layer, and the thickness of the SOI layer is reduced to less than a thickness 1.4 times the thickness of the BOX layer by performing a sacrificial oxidation treatment on the SOI layer of the SOI wafer after the flattening heat treatment.
    Type: Grant
    Filed: September 1, 2010
    Date of Patent: February 17, 2015
    Assignee: Shin-Etsu Handotai Co., Ltd.
    Inventors: Isao Yokokawa, Masahiro Kato, Masayuki Imai
  • Patent number: 8906708
    Abstract: A method for checking an ion implantation condition when ions are implanted over an entirety of one surface of a semiconductor wafer having an insulator film on the one surface, the method including checking whether the ions are implanted over the entirety of the one surface of the semiconductor wafer by directly or indirectly observing light emitted when the one surface of the semiconductor wafer is irradiated with an ion beam of the implanted ions throughout the ion implantation.
    Type: Grant
    Filed: March 28, 2011
    Date of Patent: December 9, 2014
    Assignee: Shin-Etsu Handotai Co., Ltd.
    Inventor: Isao Yokokawa
  • Publication number: 20140322895
    Abstract: According to the present invention, there is provided a method for manufacturing an SOI wafer having the step of performing a first sacrificial oxidation treatment on the aforementioned bonded SOI wafer in which the delamination has been performed after a first RTA treatment has been performed thereon and then performing a second sacrificial oxidation treatment thereon after a second RTA treatment has been performed thereon, wherein the first and second RTA treatments are performed under a hydrogen gas containing atmosphere and at a temperature of 1100° C. or more, wherein after a thermal oxide film has been formed on the aforementioned SOI layer front surface by performing only thermal oxidation by a batch type heat treating furnace at a temperature of 900° C. or more and 1000° C. or less in the first and second sacrificial oxidation treatments, a treatment for removing the thermal oxide film is performed.
    Type: Application
    Filed: November 30, 2012
    Publication date: October 30, 2014
    Applicant: SHIN-ETSU HANDOTAI CO., LTD.
    Inventors: Norihiro Kobayashi, Hiroji Aga, Isao Yokokawa, Toru Ishizuka, Masahiro Kato
  • Publication number: 20140186977
    Abstract: A method for calculating a warpage of a bonded SOI wafer includes: assuming that the epitaxial growth SOI wafer is a silicon single crystal wafer having the same dopant concentration as dopant concentration of the bond wafer; calculating a warpage A that occurs at the time of performing the epitaxial growth relative to the assumed silicon single crystal wafer; calculating a warpage B caused due to a thickness of the BOX layer of the epitaxial growth SOI wafer; determining a measured value of a warpage of the base wafer before bonding as a warpage C; and calculating a sum of the warpages (A+B+C) as the warpage of the bonded SOI wafer.
    Type: Application
    Filed: August 21, 2012
    Publication date: July 3, 2014
    Applicant: SHIN-ETSU HANDOTAI CO., LTD.
    Inventors: Isao Yokokawa, Hiroji Aga, Yasushi Mizusawa
  • Patent number: 8728912
    Abstract: The present invention is directed to a method for manufacturing an SOI wafer, the method by which treatment that removes the outer periphery of a buried oxide film to obtain a structure in which a peripheral end of an SOI layer of an SOI wafer is located outside a peripheral end of the buried oxide film, and, after heat treatment is performed on the SOI wafer in a reducing atmosphere containing hydrogen or an atmosphere containing hydrogen chloride gas, an epitaxial layer is formed on a surface of the SOI layer. As a result, there is provided a method that can manufacture an SOI wafer having a desired SOI layer thickness by performing epitaxial growth without allowing a valley-shaped step to be generated in an SOI wafer with no silicon oxide film in a terrace portion, the SOI wafer fabricated by an ion implantation delamination method.
    Type: Grant
    Filed: November 18, 2011
    Date of Patent: May 20, 2014
    Assignee: Shin-Etsu Handotai Co., Ltd.
    Inventors: Hiroji Aga, Isao Yokokawa, Satoshi Oka
  • Publication number: 20140097523
    Abstract: A method for manufacturing a bonded wafer includes: an ion implantation step of using a batch type ion implanter; a bonding step of bonding an ion implanted surface of a bond wafer to a surface of a base wafer directly or through an insulator film; and a delamination step of delaminating the bond wafer at an ion implanted layer, thereby manufacturing a bonded wafer having a thin film on the base wafer, wherein the ion implantation into the bond wafer carried out at the ion implantation step is divided into a plurality of processes, the bond wafer is rotated on its own axis a predetermined rotation angle after each ion implantation, and the next ion implantation is carried out at an arrangement position obtained by the rotation.
    Type: Application
    Filed: April 25, 2012
    Publication date: April 10, 2014
    Applicant: SHIN-ETSU HANDOTAI CO., LTD.
    Inventors: Hiroji Aga, Isao Yokokawa, Nobuhiko Noto
  • Publication number: 20130316522
    Abstract: The present invention is directed to a method for manufacturing an SOI wafer, the method by which treatment that removes the outer periphery of a buried oxide film to obtain a structure in which a peripheral end of an SOI layer of an SOI wafer is located outside a peripheral end of the buried oxide film, and, after heat treatment is performed on the SOI wafer in a reducing atmosphere containing hydrogen or an atmosphere containing hydrogen chloride gas, an epitaxial layer is formed on a surface of the SOI layer. As a result, there is provided a method that can manufacture an SOI wafer having a desired SOI layer thickness by performing epitaxial growth without allowing a valley-shaped step to be generated in an SOI wafer with no silicon oxide film in a terrace portion, the SOI wafer fabricated by an ion implantation delamination method.
    Type: Application
    Filed: November 18, 2011
    Publication date: November 28, 2013
    Applicant: SHIN-ETSU HANDOTAI CO., LTD.
    Inventors: Hiroji Aga, Isao Yokokawa, Satoshi Oka
  • Patent number: 8361888
    Abstract: The present invention provides a method for manufacturing an SOI wafer wherein an HCl gas is mixed in a reactive gas at a step of forming a silicon epitaxial layer on an entire surface of an SOI layer of the SOI wafer having an oxide film on a terrace portion. As a result, it is possible to provide the method for manufacturing an SOI wafer that can easily grow the silicon epitaxial layer on the SOI layer of the SOI wafer having the oxide film on the terrace portion, suppress warpage of the SOI wafer to be manufactured, reduce generation of particles even at subsequent steps, e.g., device manufacture, and decrease a cost for manufacturing such an SOI wafer.
    Type: Grant
    Filed: May 27, 2008
    Date of Patent: January 29, 2013
    Assignee: Shin-Etsu Handotai Co., Ltd.
    Inventors: Isao Yokokawa, Nobuhiko Noto
  • Publication number: 20130023069
    Abstract: A method for checking an ion implantation condition when ions are implanted over an entirety of one surface of a semiconductor wafer having an insulator film on the one surface, the method including checking whether the ions are implanted over the entirety of the one surface of the semiconductor wafer by directly or indirectly observing light emitted when the one surface of the semiconductor wafer is irradiated with an ion beam of the implanted ions throughout the ion implantation.
    Type: Application
    Filed: March 28, 2011
    Publication date: January 24, 2013
    Applicant: SHIN-ETSU HANDOTAI CO., LTD.
    Inventor: Isao Yokokawa
  • Publication number: 20120135584
    Abstract: A method for manufacturing an SOI wafer includes performing a flattening heat treatment on an SOI wafer under an atmosphere containing an argon gas, in which conditions of SOI wafer preparation are set so that a thickness of an SOI layer of the SOI wafer to be subjected to the flattening heat treatment is 1.4 or more times thicker than that of a BOX layer, and the thickness of the SOI layer is reduced to less than a thickness 1.4 times the thickness of the BOX layer by performing a sacrificial oxidation treatment on the SOI layer of the SOI wafer after the flattening heat treatment.
    Type: Application
    Filed: September 1, 2010
    Publication date: May 31, 2012
    Applicant: SHIN-ETSU HANDOTAI CO., LTD.
    Inventors: Isao Yokokawa, Masahiro Kato, Masayuki Imai
  • Publication number: 20110281420
    Abstract: A method for manufacturing an SOI wafer including implanting a gas ion into a bond wafer from a surface thereof to form an ion-implanted layer; bonding the ion-implanted surface of the bond wafer to a surface of a base wafer through an insulator film; and delaminating the bond wafer at the ion-implanted layer to manufacture the SOI wafer. The method further includes immersing the bonded wafer prior to the delamination of the bond wafer at the ion-implanted layer into a liquid capable of dissolving the insulator film or exposing the bonded wafer to a gas capable of dissolving the insulator film so that the insulator film located between the bond wafer and the base wafer is etched from an outer circumferential edge toward a center of the bonded wafer.
    Type: Application
    Filed: January 8, 2010
    Publication date: November 17, 2011
    Applicant: SHIN-ETSU HANDOTAI CO., LTD.
    Inventors: Hiroji Aga, Isao Yokokawa, Nobuhiko Noto
  • Patent number: 8053334
    Abstract: The invention is a method for forming a silicon oxide film of an SOI wafer, the method by which at least thermal oxidation treatment is performed (a process (A)) on an SOI wafer having an oxide film on the back surface and, after the thermal oxidation treatment, heat treatment is additionally performed (a process (B)) in a non-oxidizing atmosphere at a temperature higher than the temperature at which the thermal oxidation treatment was performed, whereby a silicon oxide film is formed on the front surface of an SOI layer. This provides a method for forming a silicon oxide film of an SOI wafer, the method that can prevent an SOI wafer from being warped after thermal oxidation treatment even when an SOI wafer having a thick oxide film on the back surface is used and a silicon oxide film for forming a device is formed by thermal oxidation on the front surface on the SOI layer side, and can reduce exposure failure and adsorption failure caused by warpage of the SOI wafer and enhance yields of device fabrication.
    Type: Grant
    Filed: April 25, 2008
    Date of Patent: November 8, 2011
    Assignee: Shin-Etsu Handotai Co., Ltd.
    Inventors: Isao Yokokawa, Nobuhiko Noto, Shin-ichi Yamaguchi
  • Patent number: 7985660
    Abstract: The present invention provides a method for manufacturing an SOI wafer, including: a step of preparing a base wafer consisting of a p+ silicon single crystal wafer and a bond wafer consisting of a silicon single crystal wafer containing a dopant at a lower concentration than that in the base wafer; a step of forming a silicon oxide film on an entire surface of the base wafer based on thermal oxidation; a step of bonding the bond wafer to the base wafer through the silicon oxide film; and a step of reducing a thickness of the bond wafer to form an SOI layer, wherein a step of forming a CVD insulator film on a surface on an opposite side of a bonding surface of the base wafer is provided before the thermal oxidation step for the base wafer.
    Type: Grant
    Filed: April 16, 2008
    Date of Patent: July 26, 2011
    Assignee: Shin Etsu Handotai Co., Ltd.
    Inventors: Isao Yokokawa, Hiroshi Takeno, Nobuhiko Noto
  • Patent number: 7959731
    Abstract: A method for producing a semiconductor wafer, including epitaxially growing a Si1-XGeX layer (0<X?1) on a surface of a silicon single crystal wafer to be a bond wafer; implanting at least one kind of a hydrogen ion or a rare gas ion through the Si1-XGeX layer and forming an ion-implanted layer inside the bond wafer; contacting and bonding a surface of the Si1-XGeX layer and a surface of a base wafer through an insulator film; then performing delamination at the ion-implanted layer; performing a bonding heat treatment of binding the bonded surfaces; and then removing a Si layer of a delaminated layer transferred to a side of the base wafer by the delamination. Thereby, the method does not cause lattice relaxation in the SiGe layer. Therefore, the method is suitable for production of a semiconductor wafer for high-speed semiconductor devices.
    Type: Grant
    Filed: November 2, 2005
    Date of Patent: June 14, 2011
    Assignee: Shin-Etsu Handotai Co., Ltd.
    Inventors: Isao Yokokawa, Hiroji Aga, Kiyoshi Mitani
  • Publication number: 20100129993
    Abstract: The present invention provides a method for manufacturing an SOI wafer wherein an HCl gas is mixed in a reactive gas at a step of forming a silicon epitaxial layer on an entire surface of an SOI layer of the SOI wafer having an oxide film on a terrace portion. As a result, it is possible to provide the method for manufacturing an SOI wafer that can easily grow the silicon epitaxial layer on the SOI layer of the SOI wafer having the oxide film on the terrace portion, suppress warpage of the SOI wafer to be manufactured, reduce generation of particles even at subsequent steps, e.g., device manufacture, and decrease a cost for manufacturing such an SOI wafer.
    Type: Application
    Filed: May 27, 2008
    Publication date: May 27, 2010
    Applicant: SHIN-ETSU HANDOTAI CO., LTD.
    Inventors: Isao Yokokawa, Nobuhiko Noto
  • Publication number: 20100112824
    Abstract: The invention is a method for forming a silicon oxide film of an SOI wafer, the method by which at least thermal oxidation treatment is performed (a process (A)) on an SOI wafer having an oxide film on the back surface and, after the thermal oxidation treatment, heat treatment is additionally performed (a process (B)) in a non-oxidizing atmosphere at a temperature higher than the temperature at which the thermal oxidation treatment was performed, whereby a silicon oxide film is formed on the front surface of an SOI layer. This provides a method for forming a silicon oxide film of an SOI wafer, the method that can prevent an SOI wafer from being warped after thermal oxidation treatment even when an SOI wafer having a thick oxide film on the back surface is used and a silicon oxide film for forming a device is formed by thermal oxidation on the front surface on the SOI layer side, and can reduce exposure failure and adsorption failure caused by warpage of the SOI wafer and enhance yields of device fabrication.
    Type: Application
    Filed: April 25, 2008
    Publication date: May 6, 2010
    Applicant: SHIN-ETSU HANDOTAI CO., LTD.
    Inventors: Isao Yokokawa, Nobuhiko Noto, Shin-ichi Yamaguchi
  • Publication number: 20100112781
    Abstract: The present invention provides a method for manufacturing an SOI wafer, including: a step of preparing a base wafer consisting of a p+ silicon single crystal wafer and a bond wafer consisting of a silicon single crystal wafer containing a dopant at a lower concentration than that in the base wafer; a step of forming a silicon oxide film on an entire surface of the base wafer based on thermal oxidation; a step of bonding the bond wafer to the base wafer through the silicon oxide film; and a step of reducing a thickness of the bond wafer to form an SOI layer, wherein a step of forming a CVD insulator film on a surface on an opposite side of a bonding surface of the base wafer is provided before the thermal oxidation step for the base wafer.
    Type: Application
    Filed: April 16, 2008
    Publication date: May 6, 2010
    Applicant: SHIN-ETSU HANDOTAI CO., LTD.
    Inventors: Isao Yokokawa, Hiroshi Takeno, Nobuhiko Noto
  • Patent number: 7608548
    Abstract: Disclosed is a method for cleaning a multilayer substrate at least having a silicon single crystal wafer with a SiGe layer epitaxially grown on a surface of the silicon single crystal wafer, where the SiGe layer is an outermost surface of the SiGe layer and then cleaning the multilayer substrate with a first cleaning liquid capable of etching the protective film so that the protective film remains. The protective film prevents roughening of the surface of the SiGe layer while the cleaning is performed. The cleaning is performed. The cleaning is performed so that a thickness of the remaining protective film is from 1 nm to 100 nm.
    Type: Grant
    Filed: September 7, 2004
    Date of Patent: October 27, 2009
    Assignee: Shin-Etsu Handotai Co., Ltd.
    Inventors: Isao Yokokawa, Kiyoshi Mitani
  • Patent number: 7550309
    Abstract: The present invention is a method for producing a semiconductor wafer, comprising at least steps of, epitaxially growing a Si1-XGeX layer (0<X<1) on an SOI wafer, forming a Si1-YGeY layer (0?Y<X) on the epitaxially grown Si1-XGeX layer, and then enriching Ge in the epitaxially grown Si1-XGeX layer by an oxidation heat treatment so that the Si1-XGeX layer becomes an enriched SiGe layer, wherein, at least, the oxidation heat treatment is initiated from 950° C. or less under an oxidizing atmosphere, and the oxidation is performed so that the formed Si1-YGeY layer remains during a temperature rise to 950° C. Thereby, there can be provided a method for producing a semiconductor wafer by which the lattice relaxation of the SiGe layer in an SGOI wafer can be sufficiently performed by a heat treatment for a short time and its production cost can be reduced.
    Type: Grant
    Filed: September 16, 2005
    Date of Patent: June 23, 2009
    Assignee: Shin-Etsu Handotai Co., Ltd.
    Inventors: Isao Yokokawa, Nobuhiko Noto, Kiyoshi Mitani
  • Patent number: 7524744
    Abstract: The present invention provides a method of producing an SOI wafer, comprising at least steps of forming an oxygen ion-implanted layer by implanting oxygen ions into a silicon wafer from one main surface thereof, subjecting the silicon wafer to oxide film-forming heat treatment to convert the oxygen ion-implanted layer into a buried oxide film, and thereby producing an SOI wafer having an SOI layer on the buried oxide film, wherein when the buried oxide film is formed in the silicon wafer, the buried oxide film is formed so that a thickness thereof is thicker than a thickness of the buried oxide film which the SOI wafer to be produced has, and thereafter the silicon wafer in which the thicker buried oxide film is formed is subjected to a heat treatment to reduce the thickness of the buried oxide film.
    Type: Grant
    Filed: February 13, 2004
    Date of Patent: April 28, 2009
    Assignee: Shin-Etsu Handotai Co., Ltd.
    Inventors: Isao Yokokawa, Hiroji Aga, Kiyotaka Takano, Kiyoshi Mitani