Patents by Inventor Stefan A. Wolff

Stefan A. Wolff 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: 5643364
    Abstract: A plasma chamber RF excitation system includes a high frequency RF power source having a fixed RF match circuit at its output and sensing and control apparatus for sensing the amount of RF power delivered by the RF power source and for regulating the output power level of the RF power source so as to maintain the RF power delivered by the RF power source at a desired level, and an RF plasma chamber including an RF radiator. The power source is mounted proximate or directly on the plasma chamber so that the distance between them is much less than an eighth of a wavelength at thr frequency of the RF source. The system may further include an endpoint detector for a plasma etch process or a chamber cleaning process which halts the process when the VSWR or reflected power ceases to change in response to the progress of the etch process.
    Type: Grant
    Filed: May 2, 1996
    Date of Patent: July 1, 1997
    Assignee: Applied Materials, Inc.
    Inventors: Jun Zhao, Stefan Wolff, Kenneth Smyth, William Nixon Taylor, Jr., Gerald McNutt
  • Patent number: 5641851
    Abstract: The invention is to a process for the preparation of biuret-containing polyisocyanates by catalytic reaction of aliphatic and/or cycloaliphatic diisocyanates with a biuretizing agent, where the biuretizing agent employed is water in finely disperse form and the reaction is carried out in the presence of OH-acidic compounds.
    Type: Grant
    Filed: October 31, 1995
    Date of Patent: June 24, 1997
    Assignee: BASF Aktiengesellschaft
    Inventors: Stefan Wolff, Wolfgang Heider, Werner Langer, Hans Renz
  • Patent number: 5558717
    Abstract: A process chamber is disclosed which provides a 360.degree. circular gas/vacuum distribution over a substrate being processed. The substrate being processed is supported on a heated and optionally cooled pedestal assembly. The substrate faces a one-piece gas distribution faceplate being connected to an RF power supply outside the vacuum environment of the processing chamber. A pumping channel view port is provided to verify and confirm instrumentation readings concerning the degree of surface deposition on process chamber internal surfaces. All process chamber wall surfaces facing the region where plasma will be present during processing (except the gas distribution faceplate) are ceramic and therefore highly resistant to corrosion. The pedestal an un-anodized metal is also covered with a loosely fitting ceramic surface having alignment features to maintain concentricity between the wafer support surface of the pedestal and the wafer being processed.
    Type: Grant
    Filed: November 30, 1994
    Date of Patent: September 24, 1996
    Assignee: Applied Materials
    Inventors: Jun Zhao, Tom Cho, Charles Dornfest, Stefan Wolff, Kevin Fairbairn, Xin S Guo, Alex Schreiber, John M. White
  • Patent number: 5489663
    Abstract: Polyisocyanates containing isocyanurate groups are prepared by a partial trimerization of (cyclo)aliphatic diisocyanates in the presence of at least one trimerization catalyst selected from the group consisting of tetraalkylammonium alkyl carbonates of the formula (I) ##STR1## (quaternary ammonioalkyl) carbonates having a betaine structure of the formula (II) ##STR2## and the preferred use of the polyisocyanates containing isocyanurate groups which are obtainable in this way is aspolyisocyanate component in polyurethane finishes.
    Type: Grant
    Filed: December 15, 1994
    Date of Patent: February 6, 1996
    Assignee: BASF Aktiengesellschaft
    Inventors: Peter Brandt, Bernd Bruchmann, Gerhard Laqua, Franz Merger, Andreas Otterbach, Konrad Stiefenhofer, Tom Witzel, Stefan Wolff, Rainer Becker
  • Patent number: 5436336
    Abstract: Isocyanurate- and/or uretidone-containing polyisocyanates having a reduced color index and improved shelf life are prepared by conventional catalytic oligomerization of aliphatic and/or cycloaliphatic diisocyanates and treatment of the oligomerization products with peroxycarboxylic acids.
    Type: Grant
    Filed: June 13, 1994
    Date of Patent: July 25, 1995
    Assignee: BASF Aktiengesellschaft
    Inventors: Bernd Bruchmann, Stefan Wolff, Konrad Stiefenhoefer
  • Patent number: 5369207
    Abstract: A process for the preparation of isocyanurate and urethane group-containing and, if desired, uretdiode and allophanate group-containing polyisocyanate mixtures by partially cyclizing organic, preferably (cyclo)aliphatic diisocyanates, in the presence of trimerization catalysts, deactivating these catalysts, reacting the partially trimerized, isocyanurate and, if desired, uretdiode group-containing polyisocyanate mixture with 0.5 to 10 mol % of at least one aliphatic or cycloaliphatic alcohol and/or polyoxyalkylene alcohol, and separating off the monomeric diisocyanates.
    Type: Grant
    Filed: July 12, 1993
    Date of Patent: November 29, 1994
    Assignee: BASF Aktiengesellschaft
    Inventors: Stefan Wolff, Hans Renz, Guenter Mohrhardt