Patent ID: 11967535
Assignee: KLA CORPORATION
Field: Semiconductors (Electrical engineering)
Classification: CPC H  G | IPC G  H

Claim 14:
15. The method according to claim 9, wherein forming the plurality of the overlay targets comprises:
forming the first linear grating by fabricating in the first thin-film layer a first sub-grating having a first pitch a and a second sub-grating adjacent to but non-overlapping with the first sub-grating, having a second pitch not equal to the first pitch, and
forming the second linear grating by fabricating in the second thin-film layer a third sub-grating, which has a third pitch equal to the second pitch and is overlaid on the first sub-grating, and a fourth sub-grating, which is adjacent to but non-overlapping with the third sub-grating and has a fourth pitch equal to the first pitch, and is overlaid on the second sub-grating.