The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Jan. 13, 2009
Filed:
Sep. 11, 2006
Gunther Wehrhan, Jena, DE;
Lutz Parthier, Kleinmachnow, DE;
Daniel Rytz, Herborn, DE;
Klaus Dupre, Idar-Oberstein, DE;
Lothar Ackermann, Idar-Oberstein, DE;
Gunther Wehrhan, Jena, DE;
Lutz Parthier, Kleinmachnow, DE;
Daniel Rytz, Herborn, DE;
Klaus Dupre, Idar-Oberstein, DE;
Lothar Ackermann, Idar-Oberstein, DE;
Schott AG, Mainz, DE;
Abstract
The method provides a uniform low-stress single crystal in a predetermined crystal orientation. The method of making it includes immersing a single crystal held at a temperature under its melting point in a melt of crystal raw material and drawing it from the melt to grow the crystal. The crystal and/or melt are rotated relative to each other during the crystal growth. A planar phase boundary surface is maintained by detecting at least one characteristic surface temperature in an interior of a crucible containing the melt and controlling temperature fluctuations by increasing or decreasing the rotation speed when they occur. The single crystals obtained by this method have a diameter of at least 50 mm and no visible growth strips in a fishtail pattern when a 2-mm thick sample is observed between crossed polarizers. Optical elements suitable for DUV lithography can be made from these crystals.