Patents by Inventor Andreas Ehlert

Andreas Ehlert 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: 6416393
    Abstract: A process is for producing a semiconductor wafer with a front surface and a back surface, in which the semiconductor wafer is subjected to two-sided polishing. The process includes the following: (a) producing a hydrophobic surface on the semiconductor wafer by treating the semiconductor wafer with an aqueous HF solution; (b) simultaneous polishing of the front surface and the back surface of the semiconductor wafer with a surface which has been rendered hydrophobic, with an alkaline polishing abrasive being continuously supplied between two rotating upper and lower polishing plates, which are both covered with a polishing cloth, the pH of the polishing abrasive being from pH 8.5 to pH 12.5; (c) after an intended polishing abrasion has been reached, supplying a stopping agent to the semiconductor wafer; and (d) removing the semiconductor wafer from the polishing plates.
    Type: Grant
    Filed: April 2, 2001
    Date of Patent: July 9, 2002
    Assignee: Wacker Siltronic Gesellschaft für Halbleitermaterialien AG
    Inventors: Laszlo Fabry, Gabriele Lechner, Anton Schnegg, Andreas Ehlert
  • Patent number: 6362487
    Abstract: The nondestructive detection and characterization of crystal defects in monocrystalline semiconductor material is by a combination of photoluminescence heterodyne spectroscopy, photothermal heterodyne spectroscopy and SIRD.
    Type: Grant
    Filed: May 25, 1999
    Date of Patent: March 26, 2002
    Assignee: Wacker Siltronic Gesellschaft für Halbleitermaterialien AG
    Inventors: Andreas Ehlert, Michael Kerstan, Holger Lundt, Dieter Helmreich
  • Publication number: 20010036797
    Abstract: A process is for producing a semiconductor wafer with a front surface and a back surface, in which the semiconductor wafer is subjected to two-sided polishing. The process includes the following: (a) producing a hydrophobic surface on the semiconductor wafer by treating the semiconductor wafer with an aqueous HF solution; (b) simultaneous polishing of the front surface and the back surface of the semiconductor wafer with a surface which has been rendered hydrophobic, with an alkaline polishing abrasive being continuously supplied between two rotating upper and lower polishing plates, which are both covered with a polishing cloth, the pH of the polishing abrasive being from pH 8.5 to pH 12.5; (c) after an intended polishing abrasion has been reached, supplying a stopping agent to the semiconductor wafer; and (d) removing the semiconductor wafer from the polishing plates.
    Type: Application
    Filed: April 2, 2001
    Publication date: November 1, 2001
    Applicant: WACKER SILTRONIC GESELLSCHAFT FUR HALBLEITERMATERIALIEN AG
    Inventors: Laszlo Fabry, Gabriele Lechner, Anton Schnegg, Andreas Ehlert
  • Patent number: 6267815
    Abstract: A method for pulling a single crystal has a monocrystalline seed crystal being brought into contact with molten material and an interface being formed between solid and molten material, and molten material being caused to solidify with the formation of a thin-necked crystal and a cylindrical single crystal. The method is one wherein, during the pulling of the thin-necked crystal, it is ensured that the ratio V/G(r) is above a constant Ccrit having the value 1.3*10−3 cm2/Kmin, with V being the pulling rate, with G(r) being the axial temperature gradient at the interface and r being the radial distance from the center of the thin-necked crystal.
    Type: Grant
    Filed: October 5, 1999
    Date of Patent: July 31, 2001
    Assignee: Wacker Siltronic Gesellschaft für Halbleitermaterialien AG
    Inventors: Andreas Ehlert, Erich Dornberger, Wilfried Von Ammon