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:
Sep. 04, 1984
Filed:
Jan. 26, 1982
Lee H Veneklasen, Castro Valley, CA (US);
William J DeVore, Hayward, CA (US);
The Perkin-Elmer Corp., Norwalk, CT (US);
Abstract
A composite objective lens for a particle beam lithographic system having deflection coils within the bore of the lens, a solenoidal excitation lens coil, a first set of two or more cylindrical pole pieces with a lens gap and a second set of cylindrical pole pieces arranged concentrically outside the first pole pieces but within the excitation lens coil. The second set of pole pieces is constructed of a high saturation material such as iron with a lens gap coextensive with the gap in the first set of pole pieces. The return flux from the deflection coils is carried by the inner cylindrical pole pieces only, while the flux generated by the lens coil is shared by both the inner and outer pole pieces. With this arrangement the linear relationship between the axial field strength and excitation current is maintained at all points along the axis of the lens, and saturation of the inner pole piece is avoided.