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:
Dec. 16, 1997
Filed:
Jul. 08, 1996
Richard A Allen, Gaithersburg, MD (US);
Michael W Cresswell, Gaithersburg, MD (US);
The United States of America as represented by the Secretary of Commerce, Washington, DC (US);
Abstract
Imaging instruments for inspecting products, such as semiconductor chips, e calibrated by providing a reference test structure having features which can be located by electrical measurements not subject to tool-induced shift and wafer-induced shift experienced by the imaging instrument, and by the imaging instrument. The reference test structure is first qualified using electrical measurements, and is then used to calibrate the imaging instrument. The electrical measurements are made by forcing a current between a plurality of spaced reference features and a pair of underlying conductors. Conductive connectors formed in vias in an insulating layer overlying the pair of conductors and individually connected to a respective conductive element formed on the insulating layer are each spaced at progressively greater distances relative to the centerline of the space between the pair of conductors, such that a null-overlay element may be identified.