公开(公告)号：WO2018129088A1

公开(公告)日：2018-07-12

申请号：PCT/US2018012249

申请日：2018-01-03

Applicant: KLA TENCOR CORP

Inventor： LEE MYUNGJUN ,  ROBERTSON STEWART ,  SMITH MARK D ,  SUBRAHMANYAN PRADEEP

IPC: H01L21/027 ,  H01L21/033 ,  H01L21/66

CPC classification number: G03F7/70641

Abstract: A lithography system includes an illumination source, one or more projection optical elements, and a pattern mask. The illumination source includes one or more illumination poles. The pattern mask includes a set of focus-sensitive mask elements periodically distributed with a pitch, wherein the set of focus-sensitive mask elements is configured to diffract illumination from the one or more illumination poles. The pitch is selected such that two diffraction orders of illumination associated with each of the one or more illumination poles are asymmetrically distributed in a pupil plane of the one or more projection optical elements. Further, the one or more projection optical elements are configured to expose a sample with an image of the set of focus-sensitive pattern mask elements based on the two diffraction orders of illumination associated with each of the one or more illumination poles. Additionally, one or more printing characteristics of the image of the set of focus-sensitive pattern mask elements on the sample is indicative of a position of the sample within a focal volume of the one or more projection optical elements.