System and Method for Focus Determination Using Focus-Sensitive Overlay Targets

摘要

A lithography mask is disclosed. The lithography mask includes at least one asymmetric segmented pattern element. A particular asymmetric segmented pattern element includes at least two segments with a separation distance between consecutive segments smaller than a resolution of a set of projection optics for generating an image of the particular asymmetric segmented pattern element on a sample such that the image of the particular asymmetric segmented pattern element is an unsegmented pattern image. A position of the unsegmented pattern image on the sample is indicative of a location of the sample along an optical axis of the set of projection optics.

主权项

1. A lithography mask, comprising:
at least one asymmetric segmented pattern element, wherein a particular asymmetric segmented pattern element includes at least two segments, wherein a separation distance between consecutive segments of the particular asymmetric segmented pattern element is configurable to be smaller than a resolution of a set of projection optics for generating an image of the particular asymmetric segmented pattern element on a sample such that the image of the particular asymmetric segmented pattern element is an unsegmented pattern image, wherein a position of the unsegmented pattern image on the sample is indicative of a location of the sample along an optical axis of the set of projection optics.