Mosaic overlay targets
AssigneeKLA Corporation
InventorYoel Feler
Life of this patent
Estimating the term…
Abstract
A mosaic overlay target may include two or more cell sets distributed across a sample, wherein each cell set includes one or more cells, where each cell set is oriented to have at least one of mirror symmetry with respect to a central axis of the mosaic overlay target or rotational symmetry with respect to a central point of the mosaic overlay target. The cell sets may be configured according to a metrology recipe such that images of the mosaic overlay target generated based on the metrology recipe include metrology data suitable for two or more overlay measurements. A particular one of the overlay measurements may be based on portions of the images associated with at least one of the cell sets. At least two of the two or more overlay measurements may be alternative measurements of a common property of the sample.
Claims20
A mosaic overlay target comprising:
- two or more cell sets distributed across a sample, wherein each cell set includes one or more cells having at least one of mirror symmetry with respect to a central axis of the mosaic overlay target or rotational symmetry with respect to a central point of the mosaic overlay target, wherein the two or more cell sets are configured to provide two or more different overlay measurements based on one or more images of the mosaic overlay target, wherein the two or more cell sets comprise:
- a first cell set providing a first overlay measurement along a measurement direction, wherein the first cell set includes features on both a first layer of the sample and a second layer of the sample;
- and
- a second cell set providing a second overlay measurement along the measurement direction, wherein the second cell set includes additional features on both the first layer of the sample and the second layer of the sample, wherein the first cell set is different than the second cell set and a layout of features in the first cell set is different than a layout of features in the second cell set, wherein the first overlay measurement and the second overlay measurement are alternative overlay measurements of a common property of the sample.
A method for designing a mosaic overlay target comprising:
- selecting two or more overlay measurements for generation with the mosaic overlay target;
- designing two or more cell sets of the mosaic overlay target, wherein the mosaic overlay target comprises:
- the two or more cell sets distributed across a sample, wherein each cell set includes one or more cells having at least one of mirror symmetry with respect to a central axis of the mosaic overlay target or rotational symmetry with respect to a central point of the mosaic overlay target,
- wherein the two or more cell sets are configured to provide two or more different overlay measurements based on one or more images of the mosaic overlay target when imaged, wherein the two or more cell sets comprise:
- a first cell set providing a first overlay measurement along a measurement direction, wherein the first cell set includes features on both a first layer of the sample and a second layer of the sample;
- and
- a second cell set providing a second overlay measurement along the measurement direction, wherein the second cell set includes additional features on both the first layer of the sample and the second layer of the sample, wherein the first cell set is different than the second cell set and a layout of features in the first cell set is different than a layout of features in the second cell set, wherein the first overlay measurement and the second overlay measurement are alternative overlay measurements of a common property of the sample.
Dependencies are inferred from the claim text.