Patents by Inventor Tomoyasu Aoshima

Tomoyasu Aoshima 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).

  • Anisotropic wet etching of silicon
    Patent number: 7867408
    Abstract: A silicon oxide film is formed on one principal surface of a silicon substrate by thermal oxidation, and thereafter, a silicon nitride film is formed on the silicon oxide film by CVD. A lamination layer of the silicon oxide film and silicon nitride film is selectively dry etched to form a mask opening 22 and leave an etching mask made of a left region of the lamination layer. The substrate is selectively and anisotropically etched with alkali etchant such as TMAH by using the etching mask to form a substrate opening. By setting a ration of the thickness of the silicon oxide film to the thickness of the silicon nitride film to 1.25 or larger or preferably 1.60 or larger, it is possible to prevent the deformation of the etched shape of the inner walls of the openings and cracks in the etching mask.
    Type: Grant
    Filed: June 13, 2007
    Date of Patent: January 11, 2011
    Assignee: Yamaha Corporation
    Inventor: Tomoyasu Aoshima
  • ANISOTROPIC WET ETCHING OF SILICON
    Publication number: 20070231540
    Abstract: A silicon oxide film is formed on one principal surface of a silicon substrate by thermal oxidation, and thereafter, a silicon nitride film is formed on the silicon oxide film by CVD. A lamination layer of the silicon oxide film and silicon nitride film is selectively dry etched to form a mask opening 22 and leave an etching mask made of a left region of the lamination layer. The substrate is selectively and anisotropically etched with alkali etchant such as TMAH by using the etching mask to form a substrate opening. By setting a ration of the thickness of the silicon oxide film to the thickness of the silicon nitride film to 1.25 or larger or preferably 1.60 or larger, it is possible to prevent the deformation of the etched shape of the inner walls of the openings and cracks in the etching mask.
    Type: Application
    Filed: June 13, 2007
    Publication date: October 4, 2007
    Applicant: YAMAHA CORPORATION
    Inventor: TOMOYASU AOSHIMA
  • Anisotropic wet etching of silicon
    Patent number: 7270763
    Abstract: A silicon oxide film is formed on one principal surface of a silicon substrate by thermal oxidation, and thereafter, a silicon nitride film is formed on the silicon oxide film by CVD. A lamination layer of the silicon oxide film and silicon nitride film is selectively dry etched to form a mask opening 22 and leave an etching mask made of a left region of the lamination layer. The substrate is selectively and anisotropically etched with alkali etchant such as TMAH by using the etching mask to form a substrate opening. By setting a ratio of the thickness of the silicon oxide film to the thickness of the silicon nitride film to 1.25 or larger or preferably 1.60 or larger, it is possible to prevent the deformation of the etched shape of the inner walls of the openings and cracks in the etching mask.
    Type: Grant
    Filed: February 9, 2004
    Date of Patent: September 18, 2007
    Assignee: Yamaha Corporation
    Inventor: Tomoyasu Aoshima
  • Anisotropic wet etching of silicon
    Publication number: 20040195209
    Abstract: A silicon oxide film is formed on one principal surface of a silicon substrate by thermal oxidation, and thereafter, a silicon nitride film is formed on the silicon oxide film by CVD. A lamination layer of the silicon oxide film and silicon nitride film is selectively dry etched to form a mask opening 22 and leave an etching mask made of a left region of the lamination layer. The substrate is selectively and anisotropically etched with alkali etchant such as TMAH by using the etching mask to form a substrate opening. By setting a ratio of the thickness of the silicon oxide film to the thickness of the silicon nitride film to 1.25 or larger or preferably 1.60 or larger, it is possible to prevent the deformation of the etched shape of the inner walls of the openings and cracks in the etching mask.
    Type: Application
    Filed: February 9, 2004
    Publication date: October 7, 2004
    Inventor: Tomoyasu Aoshima