US 12,411,420 B2
Small in-die target design for overlay measurement
Vladimir Levinski, Migdal HaEmek (IL)
Assigned to KLA Corporation, Milpitas, CA (US)
Filed by KLA Corporation, Milpitas, CA (US)
Filed on May 24, 2024, as Appl. No. 18/673,905.
Claims priority of provisional application 63/541,302, filed on Sep. 29, 2023.
Prior Publication US 2025/0110412 A1, Apr. 3, 2025
Int. Cl. G03F 7/00 (2006.01)
CPC G03F 7/70633 (2013.01) [G03F 7/70683 (2013.01); G03F 7/706849 (2023.05); G03F 7/706851 (2023.05)] 31 Claims
OG exemplary drawing
 
1. An overlay metrology system comprising:
a controller including one or more processors configured to execute program instructions causing the one or more processors to:
receive one or more first images of an overlay target on a sample based on illumination with an illumination beam in accordance with a metrology recipe, wherein the overlay target comprises:
a first-layer structure on a first layer of the sample, wherein the first-layer structure includes a first set of periodic features and a second set of periodic features oriented at a 90-degree angle with respect to the first set of periodic features, wherein the illumination beam is polarized at a 45-degree angle with respect to the first set of periodic features and the second set of periodic features when implementing the metrology recipe, wherein the first set of periodic features and the second set of periodic features are arranged in accordance with the metrology recipe to rotate a polarization of one or more rotated diffraction orders from the first-layer structure relative to a polarization of zero-order diffraction, wherein the one or more rotated diffraction orders include at least first-order diffraction from the first-layer structure; and
a second-layer structure on a second layer of the sample, wherein the second-layer structure includes one or more features providing an unmodified polarization direction for light emanating from the second-layer structure in response to the illumination beam;
wherein the one or more first images are generated with first polarization-filtered light aligned with the polarization of the one or more rotated diffraction orders;
receive one or more second images of the overlay target based on the illumination with the illumination beam in accordance with the metrology recipe, wherein the one or more second images are generated with second polarization-filtered light aligned orthogonal to the polarization of the one or more rotated diffraction orders; and
determine one or more overlay measurements of the sample based on the one or more first images and the one or more second images.