Kla Tencor Corporation

Daniel L Belin

Michael J Wright

David Alles

Robert W Walsh

Weston L Sousa

Zhengcheng Lin

Wilfred L Ghonsalves

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.

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

Methods and apparatus relating to the inspection of photomasks are described. In an embodiment, an inspection tool may be automatically focused on a reticle utilizing various topographic mapping techniques. Other embodiments are also described.

Auto focus system for reticle inspection

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Cupertino, CA, United States of America

Daniel L Belin