Patents by Inventor Hirotada Tobita

Hirotada Tobita 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: 10468413
    Abstract: A method of forming a three-dimensional memory device includes forming memory stack structures vertically extending through an alternating stack of insulating layers and electrically conductive layers over a substrate, such that each of the memory stack structures includes a memory film and a vertical semiconductor channel laterally surrounded by the memory film. The method also includes forming a stack of a first silicon nitride layer and a second silicon nitride layer over the memory stack structures, such that the first silicon nitride layer has a higher hydrogen-to-nitrogen ratio than the second silicon nitride layer, performing an anneal process at an elevated temperature to diffuse hydrogen from the first silicon nitride layer into the memory stack structures, and removing the first and second silicon nitride layers.
    Type: Grant
    Filed: April 6, 2018
    Date of Patent: November 5, 2019
    Assignee: SANDISK TECHNOLOGIES LLC
    Inventors: Shunsuke Takuma, Seiji Shimabukuro, Hirotada Tobita
  • Publication number: 20190312035
    Abstract: A method of forming a three-dimensional memory device includes forming memory stack structures vertically extending through an alternating stack of insulating layers and electrically conductive layers over a substrate, such that each of the memory stack structures includes a memory film and a vertical semiconductor channel laterally surrounded by the memory film. The method also includes forming a stack of a first silicon nitride layer and a second silicon nitride layer over the memory stack structures, such that the first silicon nitride layer has a higher hydrogen-to-nitrogen ratio than the second silicon nitride layer, performing an anneal process at an elevated temperature to diffuse hydrogen from the first silicon nitride layer into the memory stack structures, and removing the first and second silicon nitride layers.
    Type: Application
    Filed: April 6, 2018
    Publication date: October 10, 2019
    Inventors: Shunsuke Takuma, Seiji Shimabukuro, Hirotada Tobita
  • Patent number: 9466523
    Abstract: Contact holes are constrained to their designated active areas by etch-resistant walls so that they cannot contact adjacent active areas. Etch-resistant walls provide outer limits for any contact hole bending that may occur and thus keep contact holes substantially vertical. Mask openings for contact hole formation may be large so that they overlap etch-resistant walls.
    Type: Grant
    Filed: July 29, 2014
    Date of Patent: October 11, 2016
    Assignee: SanDisk Technologies LLC
    Inventors: Tomoyasu Kakegawa, Takuya Futase, Katsuo Yamada, Keita Kumamoto, Hirotada Tobita
  • Patent number: 9401275
    Abstract: Word lines are formed from a stack of layers that includes a metal (e.g. tungsten) layer with an overlying multi-layer cap structure. The multi-layer cap structure includes a layer with a low etch rate to protect metal from damage during anisotropic etching. The multi-layer cap structure includes a layer with stress (e.g. tensile) that is opposite to the stress of the metal (e.g. compressive) to provide low combined stress.
    Type: Grant
    Filed: September 3, 2014
    Date of Patent: July 26, 2016
    Assignee: SanDisk Technologies LLC
    Inventors: Keita Akasaki, Hirotada Tobita
  • Publication number: 20160064276
    Abstract: Word lines are formed from a stack of layers that includes a metal (e.g. tungsten) layer with an overlying multi-layer cap structure. The multi-layer cap structure includes a layer with a low etch rate to protect metal from damage during anisotropic etching. The multi-layer cap structure includes a layer with stress (e.g. tensile) that is opposite to the stress of the metal (e.g. compressive) to provide low combined stress.
    Type: Application
    Filed: September 3, 2014
    Publication date: March 3, 2016
    Inventors: Keita Akasaki, Hirotada Tobita
  • Publication number: 20160035738
    Abstract: Contact holes are constrained to their designated active areas by etch-resistant walls so that they cannot contact adjacent active areas. Etch-resistant walls provide outer limits for any contact hole bending that may occur and thus keep contact holes substantially vertical. Mask openings for contact hole formation may be large so that they overlap etch-resistant walls.
    Type: Application
    Filed: July 29, 2014
    Publication date: February 4, 2016
    Inventors: Tomoyasu Kakegawa, Takuya Futase, Katsuo Yamada, Keita Kumamoto, Hirotada Tobita
  • Publication number: 20060157768
    Abstract: In a method for fabricating a semiconductor device according to the present invention, gate injection for an n-type MIS transistor region is performed with an n-type decoupling capacitor region covered. Thus, compared to a known method, an n-type impurity concentration in a capacitor electrode in the n-type decoupling capacitor region.
    Type: Application
    Filed: November 22, 2005
    Publication date: July 20, 2006
    Inventors: Hirotada Tobita, Atsushi Koshio