Patents by Inventor Isamu Asano

Isamu Asano 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).

  • Publication number: 20070141786
    Abstract: A method of manufacturing a non-volatile memory element in the present invention comprises a first step for forming an adhesion layer on an interlayer insulating film so that an electrical connection is established with a lower electrode, a second step for forming a recording layer containing a phase change material on the adhesion layer, a third step for forming an upper electrode that is electrically connected to the recording layer, and a fourth step for diffusing in the recording layer some of the adhesion layer positioned between at least the lower electrode and the recording layer.
    Type: Application
    Filed: December 12, 2006
    Publication date: June 21, 2007
    Inventors: Tsuyoshi Kawagoe, Isamu Asano
  • Publication number: 20070123018
    Abstract: A non-volatile memory element includes a lower electrode, an upper electrode, a recording layer arranged between the lower electrode and the upper electrode and containing a phase change material, and a bit line directly arranged on the upper electrode. The bit line is formed to be offset to the recording layer. With this arrangement, a contact area between the recording layer and the upper electrode and a contact area between the upper electrode and the bit line can be reduced without providing an interlayer insulation film between the upper electrode and the bit line. Thus, heat radiation to the bit line can be suppressed while the upper electrode and the bit line are connected without using a through-hole.
    Type: Application
    Filed: November 9, 2006
    Publication date: May 31, 2007
    Inventor: Isamu Asano
  • Patent number: 7224016
    Abstract: A semiconductor device includes memory cells each having an MISFET for memory selection formed on one major surface of a semiconductor substrate and a capacitive element comprised of a lower electrode electrically connected at a bottom portion to one of a source and drain of the MISFET for memory selection via a first metal layer and an upper electrode formed on the lower electrode via a capacitive insulating film. The lower electrode has a thickness of 30 nm or greater at the bottom portion thereof. Sputtering with a high ionization ratio and high directivity, such as PCM, is adapted to the formation of the lower electrode to make only the bottom portion of a capacitor thicker.
    Type: Grant
    Filed: February 13, 2004
    Date of Patent: May 29, 2007
    Assignees: Elpida Memory, Inc., Hitachi ULSI Systems, Co., Ltd., Hitachi Ltd.
    Inventors: Yoshitaka Nakamura, Hidekazu Goto, Isamu Asano, Mitsuhiro Horikawa, Keiji Kuroki, Hiroshi Sakuma, Kenichi Koyanagi, Tsuyoshi Kawagoe
  • Publication number: 20070097738
    Abstract: A non-volatile memory element comprising a bottom electrode 12, a top electrode 17 provided on the bottom electrode 12, and a recording layer 18 containing phase change material connected between the bottom electrode 12 and the top electrode 17. In accordance with this invention, the top electrode 17 is in contact with a growth initiation surface 18a of the recording layer 17. This structure can be obtained by forming the top electrode 17 before the recording layer 18, resulting in a three-dimensional structure. This decreases heat dissipation to the bit line without increasing the thickness of the recording layer 18.
    Type: Application
    Filed: November 3, 2005
    Publication date: May 3, 2007
    Inventors: Isamu Asano, Tyler Lowrey
  • Publication number: 20070096074
    Abstract: A non-volatile memory element includes a first interlayer insulation layer 11 having a first through-hole 11a, a second interlayer insulation layer 12 having a second through-hole 12a formed on the first interlayer insulation layer 11, a bottom electrode 13 provided in the first through-hole 11, recording layer 15 containing phase change material provided in the second through-hole 12, a top electrode 16 provided on the second interlayer insulation layer 12, and a thin-film insulation layer 14 formed between the bottom electrode 13 and the recording layer 15. In accordance with this invention, the diameter D1 of a bottom electrode 13 buried in a first through-hole 11a is smaller than the diameter D2 of a second through-hole 12a, thereby decreasing the thermal capacity of the bottom electrode 13.
    Type: Application
    Filed: November 2, 2005
    Publication date: May 3, 2007
    Inventors: Isamu Asano, Natsuki Sato, Tyler Lowrey, Guy Wicker, Wolodymyr Czubatyj, Stephen Hudgens
  • Publication number: 20070097737
    Abstract: A non-volatile memory element includes a bottom electrode 12, a bit line 14 provided on the bottom electrode 12, and a recording layer 15 containing phase change material connected between the bottom electrode 12 and the bit line 14. In accordance with this invention, the bit line 14 is in contact with a growth initiation surface 15a of the recording layer 15. This structure can be obtained by forming the bit line 14 before the recording layer 15, resulting in a three-dimensional structure. This decreases the area of contact between the recording layer 15 and the bit line 14, decreasing heat dissipation to the bit line 14 without increasing the thickness of the recording layer 15. With this three-dimensional structure, moreover, there is no top electrode between the bit line 14 and the recording layer 15, keeping down the complexity of the fabrication process.
    Type: Application
    Filed: November 2, 2005
    Publication date: May 3, 2007
    Inventors: Isamu Asano, Tyler Lowrey
  • Publication number: 20070090336
    Abstract: In a semiconductor memory comprising a matrix of memory cells each composed of one transistor and one chalcogenide layer as a memory element, no chalcogenide layer is disposed at a joint between an upper electrode wire connected to the chalcogenide layer and another wiring layer.
    Type: Application
    Filed: July 7, 2006
    Publication date: April 26, 2007
    Inventors: Isamu Asano, Tsuyoshi Kawagoe
  • Publication number: 20070063180
    Abstract: A non-volatile memory element includes a recording layer that includes a phase change material, a lower electrode provided in contact with the recording layer, an upper electrode provided in contact with a portion of the upper surface of the recording layer, a protective insulation film provided in contact with the other portion of the upper surface of the recording layer, and an interlayer insulation film provided on the protective insulation film. High thermal efficiency can thereby be obtained because the size of the area of contact between the recording layer and the upper electrode is reduced. Providing the protective insulation film between the interlayer insulation film and the upper surface of the recording layer makes it possible to reduce damage sustained by the recording layer during patterning of the recording layer or during formation of the through-hole for exposing a portion of the recording layer.
    Type: Application
    Filed: September 7, 2006
    Publication date: March 22, 2007
    Inventors: Isamu Asano, Natsuki Sato, Kiyoshi Nakai
  • Publication number: 20070063181
    Abstract: A radial memory device includes a phase-change material, a first electrode in electrical communication with the phase-change material, the first electrode having a first area of electrical communication with the phase-change material. A second electrode in electrical communication with the phase-change material, the second electrode having a second area of electrical communication with the phase-change material, and the second area being laterally spacedly disposed from the first area. Additionally, the radial memory device includes a dielectric layer disposed between the first electrode and the second electrode, the dielectric layer having an opening therethrough, the phase-change material being disposed in the opening, wherein the phase-change material is disposed at least partially above the second electrode. Further, a method of making a memory device is disclosed.
    Type: Application
    Filed: November 21, 2006
    Publication date: March 22, 2007
    Inventors: Wolodymyr Czubatyj, Tyler Lowrey, Isamu Asano
  • Patent number: 7183170
    Abstract: After an upper electrode protective film is formed such that it is in a firm contact with ruthenium film of the upper electrode without damaging the ruthenium film, the upper electrode is etched, thereby, a MIM capacitor is obtained in which leak current is not increased due to oxidation of the ruthenium film of the upper electrode.
    Type: Grant
    Filed: November 30, 2004
    Date of Patent: February 27, 2007
    Assignee: Elpida Memory, Inc.
    Inventors: Yoshitaka Nakamura, Tsuyoshi Kawagoe, Hiroshi Sakuma, Isamu Asano, Keiji Kuroki, Hidekazu Goto, Shinpei Iijima
  • Patent number: 7145193
    Abstract: In a peripheral circuit region of a DRAM, two connection holes, for connecting a first layer line and a second layer line electrically are opened separately in two processes. After forming the connection holes, plugs are formed in the respective connection holes.
    Type: Grant
    Filed: August 29, 2002
    Date of Patent: December 5, 2006
    Assignee: Hitachi, Ltd.
    Inventors: Yoshitaka Nakamura, Isamu Asano, Keizou Kawakita, Satoru Yamada
  • Publication number: 20060239097
    Abstract: Disclosed is a semiconductor storage apparatus in which two sorts of memories, that is, a volatile memory and a non-volatile memory, are mounted on one chip. Data of a DRAM memory array are saved in a corresponding area of a non-volatile memory before entry to a data retention mode or before power down and data is transferred from the area of the non-volatile memory to the DRAM memory array in exiting from the data retention mode or power up. Normal read/write access is made to the DRAM memory array, while data retention is in an area of the non-volatile memory.
    Type: Application
    Filed: April 24, 2006
    Publication date: October 26, 2006
    Applicant: EPLIDA MEMORY, INC.
    Inventors: Kiyoshi Nakai, Kazuhiko Kajigaya, Isamu Asano
  • Patent number: 7122469
    Abstract: With a view to preventing the oxidation of a metal film at the time of light oxidation treatment after gate patterning and at the same time to making it possible to control the reproducibility of oxide film formation and homogeneity of oxide film thickness at gate side-wall end portions, in a gate processing step using a poly-metal, a gate electrode is formed by patterning a gate electrode material which has been deposited over a semiconductor wafer 1A having a gate oxide film formed thereon and has a poly-metal structure and then, the principal surface of the semiconductor wafer 1A heated to a predetermined temperature or vicinity thereof is supplied with a hydrogen gas which contains water at a low concentration, the water having been formed from hydrogen and oxygen by a catalytic action, to selectively oxidize the principal surface of the semiconductor wafer 1A, whereby the profile of the side-wall end portions of the gate electrode is improved
    Type: Grant
    Filed: August 4, 2005
    Date of Patent: October 17, 2006
    Assignee: Hitachi, Ltd.
    Inventors: Yoshikazu Tanabe, Isamu Asano, Makoto Yoshida, Naoki Yamamoto, Masayoshi Saito, Nobuyoshi Natsuaki
  • Patent number: 7119443
    Abstract: The semiconductor device is formed according to the following steps. A TiN film 71 and a W film 72 are deposited on a silicon oxide film 64 including the inside of a via-hole 66 by the CVD method and thereafter, the W film 72 and TiN film 71 on the silicon oxide film 64 are etched back to leave only the inside of the via-hole 66 and form a plug 73. Then, a TiN film 74, Al-alloy film 75, and Ti film 76 are deposited on the silicon oxide film 64 including the surface of the plug 73 by the sputtering method and thereafter, the Ti film 76, Al-alloy film 75, and TiN film 74 are patterned to form second-layer wirings 77 and 78.
    Type: Grant
    Filed: October 7, 2004
    Date of Patent: October 10, 2006
    Assignee: Hitachi, Ltd.
    Inventors: Yoshitaka Nakamura, Tsuyoshi Tamaru, Naoki Fukuda, Hidekazu Goto, Isamu Asano, Hideo Aoki, Keizo Kawakita, Satoru Yamada, Katsuhiko Tanaka, Hiroshi Sakuma, Masayoshi Hirasawa
  • Publication number: 20060211231
    Abstract: A memory device in which both DRAM and phase-change memory (PCRAM) are mounted is provided with a DRAM bit line, a PCRAM bit line or a PCRAM source line formed on an conductive layer shared with the DRAM bit line, and a sense amplifier connected between the DRAM bit line and the PCRAM bit line. The memory device further has a capacitive element disposed on the upper layer of the DRAM bit line, and a phase-change element disposed on the upper layer of the PCRAM bit line. The lower electrode of the capacitive element and the lower electrode of the phase-change memory element are formed on the shared conductive layer.
    Type: Application
    Filed: March 14, 2006
    Publication date: September 21, 2006
    Inventors: Isamu Asano, Tsuyoshi Kawagoe, Kiyoshi Nakai, Yukio Fuji, Kazuhiko Kajigaya
  • Publication number: 20060176724
    Abstract: A phase change memory device, comprising a phase change memory device; a semiconductor substrate; a MOS transistor disposed at each intersection of a plurality of word lines and a plurality of bit lines arranged in a matrix form; a plurality of phase change memory elements for storing data of a plurality of bits, each formed on an upper area opposite to a diffusion layer of the MOS transistor in a phase change layer made of phase change material; a lower electrode structure for electrically connecting each of the plurality of phase change memory elements to the diffusion layer of the MOS transistor.
    Type: Application
    Filed: February 9, 2006
    Publication date: August 10, 2006
    Inventors: Isamu Asano, Yukio Fuji, Kiyoshi Nakai, Tsuyoshi Kawagoe
  • Publication number: 20060151771
    Abstract: A phase-change memory device includes a plurality of bit lines extending in a row direction, a plurality of selection lines extending in a column direction, and an array of memory cells each disposed at one of intersections between the bit lines and selection lines. Each memory cell includes a chalcogenide element and a diode connected in series, and an n-type contact layer underlying the n-type layer of the diode. Adjacent two of memory cells share a common bit-line contact plug connecting the n-type contact layers and the bit line.
    Type: Application
    Filed: January 11, 2006
    Publication date: July 13, 2006
    Applicant: Elpida Memory, Inc.
    Inventors: Isamu Asano, Tsuyoshi Kawagoe, Yukio Fuji, Kiyoshi Nakai, Kazuhiko Kajigaya
  • Publication number: 20060138473
    Abstract: A semiconductor device having a plurality of phase change devices rewritably storing data, comprising: an insulating film deposited on a semiconductor substrate using an insulating material having sufficient adhesion to a chalcogenide-based phase change material; a chalcogenide film formed by embedding the chalcogenide-based phase change material in a hole formed at each of bit areas separated from each other in the insulating film; and an electrode structure for supplying a current to each the phase change device made of the chalcogenide film in the bit area.
    Type: Application
    Filed: December 22, 2005
    Publication date: June 29, 2006
    Inventors: Tsuyoshi Kawagoe, Isamu Asano
  • Patent number: 7042038
    Abstract: An active region (L) with a metal insulator semiconductor field effect transistor (MISFET) (Qs) formed therein for selection of a DRAM memory cell, which makes up a memory cell of the DRAM, is arranged to have an island-like pattern that linearly extends in an X direction on one principal surface of a semiconductor substrate (1). The memory-cell selection MISFET (Qs) has an insulated gate electrode (7) (word line WL) that extends along a Y direction on the principal surface of the semiconductor substrate (1) with the same width kept along the length thereof, which gate electrode is arranged to oppose another gate electrode (7) (word line WL) adjacent thereto at a prespecified distance or pitch that is narrower than said width.
    Type: Grant
    Filed: September 4, 2003
    Date of Patent: May 9, 2006
    Assignee: Hitachi, Ltd.
    Inventors: Makoto Yoshida, Takahiro Kumauchi, Yoshitaka Tadaki, Isamu Asano, Norio Hasegawa, Keizo Kawakita
  • Patent number: 7012312
    Abstract: A highly reliable semiconductor device having a multilayer structure including an insulating film, an adjacent conductive film, and a main conductive film in which adhesive fractures, voids and disconnections are unlikely to occur. Regarding main constituent elements of the adjacent conductive film and the main conductive film, lattice mismatching is made small, the melting point the adjacent conductive film is set to be not less than 1.4 times that of the main constituent element of the main conductive film, the adjacent conductive film contains at least one different kind of element, the difference between the atomic radius of an added element and that the atomic radius the adjacent conductive film is set to be not more than 10%, and/or bond energy between the added element and silicon (Si) is not less than 1.9 times that of the main constituent element of the adjacent conductive film and silicon (Si).
    Type: Grant
    Filed: July 3, 2003
    Date of Patent: March 14, 2006
    Assignee: Hitachi, Ltd.
    Inventors: Tomio Iwasaki, Hideo Miura, Isamu Asano