Auto-focus system and methods for die-to-die inspection

• Main Authors: GHONSALVES, WILFRED L, SOUSA, WESTON L, LIN, ZHENGCHENG, BELIN, DANIEL L, WRIGHT, MICHAEL J
• Format: Patent
• Language: Chinese; English
• Published: 16.05.2015
• Subjects: APPARATUS SPECIALLY ADAPTED THEREFOR; BASIC ELECTRIC ELEMENTS; CINEMATOGRAPHY; ELECTRIC SOLID STATE DEVICES NOT OTHERWISE PROVIDED FOR; ELECTRICITY; ELECTROGRAPHY; HOLOGRAPHY; MATERIALS THEREFOR; ORIGINALS THEREFOR; PHOTOGRAPHY; PHOTOMECHANICAL PRODUCTION OF TEXTURED OR PATTERNED SURFACES,e.g. FOR PRINTING, FOR PROCESSING OF SEMICONDUCTORDEVICES; PHYSICS; SEMICONDUCTOR DEVICES

Disclosed are methods and apparatus for detecting defects in a semiconductor sample having a plurality of identically designed areas. An inspection tool is used to construct an initial focus trajectory for a first swath of the sample. The inspection tool is then used to scan the first swath by following the initial focus trajectory for the first swath while collecting autofocus data. A z offset measurement vector for each identically designed area in the first swath is generated based on the autofocus data. A corrected z offset vector is constructed for inspection of the first swath with the inspection tool. Constructing the corrected z offset vector is based on combining the z offset measurement vectors for two or more of the identically designed areas in the first swath so that the corrected z offset vector specifies a same z offset for each set of same positions in the two or more identically designed areas.