Patents by Inventor Fumio Iga

Fumio Iga 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).

  • Method of analyzing iron concentration of boron-doped P-type silicon wafer and method of manufacturing silicon wafer
    Patent number: 8481346
    Abstract: An aspect of the present invention relates to a method of analyzing an iron concentration of a boron-doped p-type silicon wafer by a SPV method, which comprises subjecting the wafer to Fe—B pair separation processing by irradiation with light and determining the iron concentration based on a change in a minority carrier diffusion length following the separation processing. The iron concentration is calculated with a calculation equation comprising a minority carrier diffusion length LAF1 measured after the separation processing, a minority carrier diffusion length LAF2 measured after a prescribed time has elapsed following measurement of LAF1, and dependence on time of recombination of Fe—B pairs separated by the separation processing. The calculation equation is derived by assuming that the irradiation with light causes boron atoms and oxygen atoms in the wafer to form a bonded product, and by assuming that the bonded product has identical influences on LAF1 and LAF2.
    Type: Grant
    Filed: July 27, 2011
    Date of Patent: July 9, 2013
    Assignee: Sumco Corporation
    Inventors: Ryuji Ohno, Fumio Iga
  • METHOD OF ANALYZING IRON CONCENTRATION OF BORON-DOPED P-TYPE SILICON WAFER AND METHOD OF MANUFACTURING SILICON WAFER
    Publication number: 20120049329
    Abstract: An aspect of the present invention relates to a method of analyzing an iron concentration of a boron-doped p-type silicon wafer by a SPV method, which comprises subjecting the wafer to Fe—B pair separation processing by irradiation with light and determining the iron concentration based on a change in a minority carrier diffusion length following the separation processing. The iron concentration is calculated with a calculation equation comprising a minority carrier diffusion length LAF1 measured after the separation processing, a minority carrier diffusion length LAF2 measured after a prescribed time has elapsed following measurement of LAF1, and dependence on time of recombination of Fe—B pairs separated by the separation processing. The calculation equation is derived by assuming that the irradiation with light causes boron atoms and oxygen atoms in the wafer to form a bonded product, and by assuming that the bonded product has identical influences on LAF1 and LAF2.
    Type: Application
    Filed: July 27, 2011
    Publication date: March 1, 2012
    Applicant: SUMCO CORPORATION
    Inventors: Ryuji OHNO, Hisao IGA, Fumio Iga