Patents Examined by Nihita Wells
  • Patent number: 6087669
    Abstract: A charged-particle-beam pattern-transfer apparatus is provided wherein a CPB is emitted from the CPB source, is focused by first and second condenser lenses, and is illuminated onto a mask. A deflector deflects the CPB to a selected subfield of the mask. The CPB transmitted by subfield is projected by a first projection lens toward a back-focal-plane aperture. The portion of the CPB that passes through the back-focal-plane aperture is projected by a second projection lens onto a wafer. Coulomb-effect-induced shifts in focal-point position, and changes in image magnification, projected-image rotation, and astigmatic blur and astigmatic distortions of the image are each corrected by application of electric current to respective components of a correction system, the correction system preferably comprising a set of correction lenses and two stigmators.
    Type: Grant
    Filed: September 2, 1998
    Date of Patent: July 11, 2000
    Assignee: Nikon Corporation
    Inventor: Shohei Suzuki