Patents by Inventor Yoshihisa Fujisaki

Yoshihisa Fujisaki 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: 6818523
    Abstract: A method for forming a semiconductor storage device includes steps of forming a memory cell transistor, forming a first plug connected to the memory cell transistor, forming a second plug of a hydrogen diffusion inhibiting layer, forming capacitor electrodes and a capacitor insulator between the capacitor electrodes and forming a hydrogen adsorption inhibiting layer.
    Type: Grant
    Filed: June 25, 2003
    Date of Patent: November 16, 2004
    Assignee: Hitachi, Ltd.
    Inventors: Hiroshi Miki, Keiko Kushida, Yasuhiro Shimamoto, Shinichiro Takatani, Yoshihisa Fujisaki, Hiromi Nakai
  • Patent number: 6815741
    Abstract: By exploiting an intense correlation exhibited between the distribution of lattice distortions in a wafer and the distribution of the threshold voltages of field effect transistors, the distribution of the lattice distortions in the wafer is reduced, thereby to mitigate the distribution of the characteristics of the semiconductor elements in the wafer. The difference between the maximum value and minimum value of the lattice distortions of a III-V single crystal at a normal temperature is set to at most 4×10−5, and the density of Si atoms contained in the III-V single crystal is set to at most 1×1016 cm−3, whereby the characteristics of semiconductor elements whose parent material is the III-V single crystal can be made uniform.
    Type: Grant
    Filed: July 23, 2003
    Date of Patent: November 9, 2004
    Assignee: Renesas Technology Corp.
    Inventors: Yoshihisa Fujisaki, Yukio Takano, Tsutomu Ishiba
  • Patent number: 6800889
    Abstract: A semiconductor device includes a capacitor having a lower electrode (102), a high-dielectric-constant or ferroelectric thin film (103), and an upper electrode (104) which are subsequently stacked. An impurity having an action of suppressing the catalytic activity of a metal or a conductive oxide constituting the electrode is added to the upper electrode (104). The addition of the impurity is effective to prevent inconveniences such as a reduction in capacitance, an insulation failure, and the peeling of the electrode due to hydrogen heat-treatment performed after formation of the upper electrode (104), and to improve the long-term reliability.
    Type: Grant
    Filed: February 13, 2002
    Date of Patent: October 5, 2004
    Assignee: Hitachi, Ltd.
    Inventors: Shinichiro Takatani, Hiroshi Miki, Keiko Kushida, Yoshihisa Fujisaki, Kazuyoshi Torii
  • Publication number: 20040124447
    Abstract: By exploiting an intense correlation exhibited between the distribution of lattice distortions in a wafer and the distribution of the threshold voltages of field effect transistors, the distribution of the lattice distortions in the wafer is reduced, thereby to mitigate the distribution of the characteristics of the semiconductor elements in the wafer. The difference between the maximum value and minimum value of the lattice distortions of a III-V single crystal at a normal temperature is set to at most 4×10−5, and the density of Si atoms contained in the III-V single crystal is set to at most 1×1016 cm−3, whereby the characteristics of semiconductor elements whose parent material is the III-V single crystal can be made uniform.
    Type: Application
    Filed: July 23, 2003
    Publication date: July 1, 2004
    Inventors: Yoshihisa Fujisaki, Yukio Takano, Tsutomu Ishiba
  • Publication number: 20040063280
    Abstract: The upper electrode of a capacitor is constituted of laminated films which act to prevent hydrogen atoms from reaching the capacitor electrodes and degrading performance. In one example, a four layer upper electrode respectively acts as a Schottky barrier layer, a hydrogen diffusion preventing layer, a reaction preventing layer, and an adsorption inhibiting layer. Therefore, the occurrence of a capacitance drop, imperfect insulation, and electrode peeling in the semiconductor device due to a reducing atmosphere can be prevented. In addition, the long-term reliability of the device can be improved.
    Type: Application
    Filed: June 25, 2003
    Publication date: April 1, 2004
    Inventors: Hiroshi Miki, Keiko Kushida, Yasuhiro Shimamoto, Shinichiro Takatani, Yoshihisa Fujisaki, Hiromi Nakai
  • Publication number: 20040043570
    Abstract: With regard to a semiconductor apparatus thermally stable in a post process and suitable for fabricating a gate insulator having a laminated structure with various high permittivity oxides and a process of producing the same, in order to achieve high function formation of a gate insulator 8, a silicon nitride film specific inductive capacity of which is approximately twice as much as that of silicon oxide and which is thermally stable and is not provided with Si—H bond, is used as at least a portion of the gate insulator 8. Further, an effective thickness of a gate insulator forming a multilayered structure insulator laminated with a metal oxide having high dielectric constant, in conversion to silicon oxide, can be thinned to less than 3 nm while restraining leakage current.
    Type: Application
    Filed: August 28, 2003
    Publication date: March 4, 2004
    Applicants: Hitachi, Ltd., Tokyo Institute of Technology
    Inventors: Yoshihisa Fujisaki, Hiroshi Ishihara
  • Patent number: 6635913
    Abstract: The upper electrode of a capacitor is constituted of laminated films which act to prevent hydrogen atoms from reaching the capacitor electrodes and degrading performance. In one example, a four layer upper electrode respectively act as a Schottky barrier layer, a hydrogen diffusion preventing layer, a reaction preventing layer, and an adsorption inhibiting layer. Therefore, the occurrence of a capacitance drop, imperfect insulation, and electrode peeling in the semiconductor device due to a reducing atmosphere can be prevented. In addition, the long-term reliability of the device can be improved.
    Type: Grant
    Filed: December 27, 2001
    Date of Patent: October 21, 2003
    Assignee: Hitachi, Ltd.
    Inventors: Hiroshi Miki, Keiko Kushida, Yasuhiro Shimamoto, Shinichiro Takatani, Yoshihisa Fujisaki, Hiromi Nakai
  • Patent number: 6632721
    Abstract: In a method of manufacturing a semiconductor integrated circuit device in which a lower electrode of a capacitor is composed of a polycrystalline silicon film having a surface area increased by surface roughening, an impurity is introduced into the polycrystalline silicon film by vapor phase diffusion in order to reduce the resistance of the lower electrode.
    Type: Grant
    Filed: June 23, 2000
    Date of Patent: October 14, 2003
    Assignees: Hitachi, Ltd., Hitachi ULSI Systems Co., Ltd.
    Inventors: Shinpei Iijima, Satoshi Yamamoto, Jun Kuroda, Hiroshi Miki, Yoshihisa Fujisaki, Tadanori Yoshida, Kenichi Yamaguchi
  • Patent number: 6630697
    Abstract: By exploiting an intense correlation exhibited between the distribution of lattice distortions in a wafer and the distribution of the threshold voltages of field effect transistors, the distribution of the lattice distortions in the wafer si reduced, thereby to mitigate the distribution of the characteristics of the semiconductor elements in the wafer. The difference between the maximum value and minimum value of the lattice distortions of a GaAs single crystal at a normal temperature is set to at most 4×10−5, and the density of Si atoms contained in the GaAs single crystal is set to at most 1×1016 cm−3, whereby the characteristics of semiconductor elements whose parent material is the GaAs single crystal can be made uniform.
    Type: Grant
    Filed: July 25, 2001
    Date of Patent: October 7, 2003
    Assignee: Hitachi, Ltd.
    Inventors: Yoshihisa Fujisaki, Yukio Takano, Tsutomu Ishiba
  • Publication number: 20020158250
    Abstract: With regard to a semiconductor apparatus thermally stable in a post process and suitable for fabricating a gate insulator having a laminated structure with various high permittivity oxides and a process of producing the same, in order to achieve high function formation of a gate insulator 8, a silicon nitride film specific inductive capacity of which is approximately twice as much as that of silicon oxide and which is thermally stable and is not provided with Si—H bond, is used as at least a portion of the gate insulator 8. Further, an effective thickness of a gate insulator forming a multilayered structure insulator laminated with a metal oxide having high dielectric constant, in conversion to silicon oxide, can be thinned to less than 3 nm while restraining leakage current.
    Type: Application
    Filed: October 30, 2001
    Publication date: October 31, 2002
    Inventors: Yoshihisa Fujisaki, Hiroshi Ishihara
  • Patent number: 6462368
    Abstract: A diffusion preventive layer extending between the bottom surface of a lower electrode and an interconnection connecting the lower electrode to one of the diffusion layer of a switching transistor is self-aligned. As a result, side trench is produced since a hole pattern is formed by using a dummy film, and even if a contact plug of a memory section is misaligned with the diffusion preventive layer, the contact plug is out of direct contact with a dielectric film having a high permittivity. Hence, a highly reliable device can be obtained.
    Type: Grant
    Filed: January 31, 2002
    Date of Patent: October 8, 2002
    Assignee: Hitachi, Ltd.
    Inventors: Kazuyoshi Torii, Yasuhiro Shimamoto, Hiroshi Miki, Keiko Kushida, Yoshihisa Fujisaki
  • Publication number: 20020140014
    Abstract: A semiconductor device includes a capacitor having a lower electrode (102), a high-dielectric-constant or ferroelectric thin film (103), and an upper electrode (104) which are subsequently stacked. An impurity having an action of suppressing the catalytic activity of a metal or a conductive oxide constituting the electrode is added to the upper electrode (104). The addition of the impurity is effective to prevent inconveniences such as a reduction in capacitance, an insulation failure, and the peeling of the electrode due to hydrogen heat-treatment performed after formation of the upper electrode (104), and to improve the long-term reliability.
    Type: Application
    Filed: February 13, 2002
    Publication date: October 3, 2002
    Inventors: Shinichiro Takatani, Hiroshi Miki, Keiko Kushida, Yoshihisa Fujisaki, Kazuyoshi Torii
  • Patent number: 6432767
    Abstract: A semiconductor device having a bottom electrode, a ferroelectric film, and a top electrode formed on a semiconductor substrate, wherein the angle of each of the main cross sectional sides of the ferroelectric film relative to the main surface of the semiconductor substrate is less than 75 degrees. Forming the ferroelectric film into the trapezoid in cross section having such an angle provides a microscopic capacitor without electrical short-circuit between the top and bottom electrodes if the top electrode, the ferroelectric film, and the bottom electrode are etched with single photolithography process step. The novel technique implements a microscopic memory cell structure suitable for highly integrated memory devices.
    Type: Grant
    Filed: July 3, 2001
    Date of Patent: August 13, 2002
    Assignee: Hitachi, Ltd.
    Inventors: Kazuyoshi Torii, Hiroshi Kawakami, Hiroshi Miki, Keiko Kushida, Yoshihisa Fujisaki, Masahiro Moniwa
  • Publication number: 20020096701
    Abstract: A diffusion preventive layer extending between the bottom surface of a lower electrode and an interconnection connecting the lower electrode to one of the diffusion layers of a switching transistor is self-aligned. As a result, no side trench is produced since a hole pattern is formed by using a dummy film, and even if a contact plug of a memory section is misaligned with the diffusion preventive layer, the contact plug is out of direct contact with a dielectric film having a high permittivity. Hence, a highly reliable device can be obtained.
    Type: Application
    Filed: January 31, 2002
    Publication date: July 25, 2002
    Applicant: Hitachi, Ltd.
    Inventors: Kazuyoshi Torii, Yasuhiro Shimamoto, Hiroshi Miki, Keiko Kushida, Yoshihisa Fujisaki
  • Patent number: 6420192
    Abstract: A semiconductor memory which is improved in reliability by preventing the lowering of capacitance and defective insulation, especially, electrode delamination. The semiconductor memory has an integrated capacitor composed of a capacitor structure constituted of an upper electrode, a lower electrode, and a capacitor insulating film (of a high-dielectric-constant or ferroelectric thin film) which is held between electrodes and serves as a capacitor insulating film, and a protective insulating film which covers the capacitor structure and is formed by plasma treatment after electrode formation. An oxygen introducing layer is formed on the surface of the capacitor insulating film. The oxygen introducing layer can be formed on the surface of the high-dielectric-constant or ferroelectric material by introducing oxygen to the boundary between the electrode and the material by conducting heat treatment in an oxygen atmosphere before the protective insulating film (SiO2 passivation film) is formed.
    Type: Grant
    Filed: October 3, 2001
    Date of Patent: July 16, 2002
    Assignee: Hitachi, Ltd.
    Inventors: Hiroshi Miki, Keiko Abdelghafar, Yoshihisa Fujisaki
  • Patent number: 6396092
    Abstract: A semiconductor device includes a capacitor having a lower electrode (102), a high-dielectric-constant or ferroelectric thin film (103), and an upper electrode (104) which are subsequently stacked. An impurity having an action of suppressing the catalytic activity of a metal or a conductive oxide constituting the electrode is added to the upper electrode (104). The addition of the impurity is effective to prevent inconveniences such as a reduction in capacitance, an insulation failure, and the peeling of the electrode due to hydrogen heat-treatment performed after formation of the upper electrode (104), and to improve the long-term reliability.
    Type: Grant
    Filed: September 20, 1999
    Date of Patent: May 28, 2002
    Assignee: Hitachi, Ltd.
    Inventors: Shinichiro Takatani, Hiroshi Miki, Keiko Kushida, Yoshihisa Fujisaki, Kazuyoshi Torii
  • Publication number: 20020056862
    Abstract: The upper electrode of a capacitor is constituted of laminated films which respectively act as a Schottky barrier layer, a hydrogen diffusion preventing layer, a reaction preventing layer, and an adsorption inhibiting layer. Therefore, the occurrence of a capacitance drop, imperfect insulation, and electrode peeling in the semiconductor device due to a reducing atmosphere can be prevented. In addition, the long-term reliability of the device can be improved.
    Type: Application
    Filed: December 27, 2001
    Publication date: May 16, 2002
    Inventors: Hiroshi Miki, Keiko Kushida, Yasuhiro Shimamoto, Shinichiro Takatani, Yoshihisa Fujisaki, Hiromi Nakai
  • Patent number: 6380574
    Abstract: A diffusion preventive layer extending between the bottom surface of a lower electrode and an interconnection connecting the lower electrode to one of the diffusion layers of a switching transistor is self-aligned. As a result, no side trench is produced since a hole pattern is formed by using a dummy film, and even if a contact plug of a memory section is misaligned with the diffusion preventive layer, the contact plug is out of direct contact with a dielectric film having a high permittivity. Hence, a highly reliable device can be obtained.
    Type: Grant
    Filed: October 31, 2000
    Date of Patent: April 30, 2002
    Assignee: Hitachi, Ltd.
    Inventors: Kazuyoshi Torii, Yasuhiro Shimamoto, Hiroshi Miki, Keiko Kushida, Yoshihisa Fujisaki
  • Publication number: 20020047147
    Abstract: Disclosed is a semiconductor device having ferroelectric capacitors above a principal surface of a substrate and a process for producing the same wherein an oriented polycrystal silicon film or an amorphous silicon film 52 is disposed on the whole area beneath a conductive diffusion barrier, 61 or 73, under a lower electrode, 62 or 74, of each ferroelectric capacitor formed in the device. As a result, the conductive diffusion barrier, the lower electrode and the capacitor ferroelectric film become oriented films; therefore, it is possible to reduce the signal variation in capacitors even in minute semiconductor devices, and obtain a highly reliable semiconductor device.
    Type: Application
    Filed: October 31, 2001
    Publication date: April 25, 2002
    Inventors: Keiko Kushida, Masahiko Hiratani, Kazuyoshi Torii, Shinichiro Takatani, Hiroshi Miki, Yuuichi Matsui, Yoshihisa Fujisaki
  • Publication number: 20020013006
    Abstract: A semiconductor memory which is improved in reliability by preventing the lowering of capacitance and defective insulation, especially, electrode delamination. The semiconductor memory has an integrated capacitor composed of a capacitor structure constituted of an upper electrode, a lower electrode, and a capacitor insulating film (of a high-dielectric-constant or ferroelectric thin film) which is held between electrodes and serves as a capacitor insulating film, and a protective insulating film which covers the capacitor structure and is formed by plasma treatment after electrode formation. An oxygen introducing layer is formed on the surface of the capacitor insulating film. The oxygen introducing layer can be formed on the surface of the high-dielectric-constant or ferroelectric material by introducing oxygen to the boundary between the electrode and the material by conducting heat treatment in an oxygen atmosphere before the protective insulating film (SiO2 passivation film) is formed.
    Type: Application
    Filed: October 3, 2001
    Publication date: January 31, 2002
    Inventors: Hiroshi Miki, Keiko Abdelghafar, Yoshihisa Fujisaki