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:
Feb. 02, 1993
Filed:
Jun. 24, 1991
Ian R Smith, Los Gatos, CA (US);
SiScan Systems, Inc., Campbell, CA (US);
Abstract
A system for inspecting and measuring the dimensions of patterned features on lithographic photomasks includes a confocal scanning microscope beneath which is mounted the photomask to be inspected. The photomask is moved to permit the imaging beam from the microscope to record reflectivity information at closely spaced points along a scan line at the metal-substrate interface within the photomask, and the unpatterned side of the mask is positioned facing the microscope so that the imaging beam passes through the transparent substrate material of the mask to the desired measurement plane. An objective lens specially corrected for imaging through transparent materials is used in the optical system, and compensating glass plates may be selectively placed between the objective lens and the photomask when the substrate of the mask is thinner than the thickness of transparent material for which the objective lens was corrected.