US 10,890,436 B2
Overlay targets with orthogonal underlayer dummyfill
Nuriel Amir, Yokne'am (IL); Guy Cohen, Yaad (IL); Vladimir Levinski, Nazareth Ilit (IL); and Michael Adel, Ya'akov (IL)
Assigned to KLA Corporation, Milpitas, CA (US)
Filed by KLA-Tencor Corporation, Milpitas, CA (US)
Filed on May 21, 2013, as Appl. No. 13/898,828.
Application 13/898,828 is a continuation in part of application No. 13/186,144, filed on Jul. 19, 2011.
Claims priority of provisional application 61/650,269, filed on May 22, 2012.
Prior Publication US 2013/0293890 A1, Nov. 7, 2013
Int. Cl. G01B 11/14 (2006.01); G03F 7/20 (2006.01)
CPC G01B 11/14 (2013.01) [G03F 7/70633 (2013.01); G03F 7/70683 (2013.01)] 41 Claims
OG exemplary drawing
 
1. An overlay target, comprising:
a first-layer overlay target structure including a plurality of overlay pattern elements segmented along a first direction, wherein the overlay target structure is formed on a first sample layer; and
a dummy target structure including a plurality of inactive pattern elements segmented along a second direction orthogonal to the first direction, wherein the dummy target structure is formed on a second sample layer different than the first sample layer, wherein the plurality of inactive pattern elements are formed from dummyfill, wherein the dummyfill provides process compatibility for regions of a sample not containing device structures based on at least one design rule, wherein at least a portion of the dummy target structure overlaps the first-layer overlay target structure, wherein the dummy target structure includes a second-layer overlay target structure formed from an aperture in the plurality of inactive pattern elements, wherein the aperture is formed adjacent to the plurality of overlay pattern elements without overlapping the plurality of overlay pattern elements, wherein overlay between the first sample layer and the second sample layer is determinable based on a location of the first-layer overlay target structure and at least one internal edge of the second-layer overlay target structure.