Metrology method, target and substrate
First Claim
1. A method comprising:
- illuminating with a measurement spot of radiation a diffraction measurement target on a substrate to produce diffracted radiation having one or more diffraction orders, the measurement target comprising at least a first sub-target, a second sub-target and a third sub-target, wherein the first, second and third sub-targets are different in design, wherein one or more selected from the first sub-target, second sub-target or third sub-target has a target structure in a first layer at least partially overlapping a target structure in a second layer, wherein each of the first to third sub-targets is designed for a different set of process stack conditions for the substrate or is designed for a different layer-pair among three or more layers for overlay measurement, and wherein the beam spot is sized so as to cover at one time at least part of each of a periodic structure of the first to third sub-targets.
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Abstract
A diffraction measurement target that has at least a first sub-target and at least a second sub-target, and wherein (1) the first and second sub-targets each include a pair of periodic structures and the first sub-target has a different design than the second sub-target, the different design including the first sub-target periodic structures having a different pitch, feature width, space width, and/or segmentation than the second sub-target periodic structure or (2) the first and second sub-targets respectively include a first and second periodic structure in a first layer, and a third periodic structure is located at least partly underneath the first periodic structure in a second layer under the first layer and there being no periodic structure underneath the second periodic structure in the second layer, and a fourth periodic structure is located at least partly underneath the second periodic structure in a third layer under the second layer.
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Citations
20 Claims
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1. A method comprising:
illuminating with a measurement spot of radiation a diffraction measurement target on a substrate to produce diffracted radiation having one or more diffraction orders, the measurement target comprising at least a first sub-target, a second sub-target and a third sub-target, wherein the first, second and third sub-targets are different in design, wherein one or more selected from the first sub-target, second sub-target or third sub-target has a target structure in a first layer at least partially overlapping a target structure in a second layer, wherein each of the first to third sub-targets is designed for a different set of process stack conditions for the substrate or is designed for a different layer-pair among three or more layers for overlay measurement, and wherein the beam spot is sized so as to cover at one time at least part of each of a periodic structure of the first to third sub-targets. - View Dependent Claims (2, 3, 4, 5, 6, 7)
- 8. A diffraction metrology target for a substrate, the diffraction metrology target comprising at least a first sub-target, a second sub-target and a third sub-target, wherein the first, second and third sub-targets are different in design, each of the first to third sub-targets is designed for a different set of process stack conditions for the substrate or is designed for a different layer-pair among three or more layers for overlay measurement, the first, second and/or third sub-target is configured to emit diffracted radiation having one or more diffraction orders, one or more selected from the first sub-target, second sub-target or third sub-target when on the substrate has a target structure in a first layer at least partially overlapping a target structure in a second layer, and at least part of a periodic structure of each of the first to third sub-targets when on a substrate is within a contiguous area of less than or equal to 400 μ
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14. A method comprising measuring overlay between two layers, the method comprising:
illuminating with a measurement spot of radiation a diffraction measurement target on a substrate having a portion of the target on each of the two layers to produce diffracted radiation having one or more diffraction orders, wherein the two layers are separated by at least one other layer, the measurement target comprises at least a first sub-target, a second sub-target and a third sub-target, wherein the first, second and third sub-targets are different in design, wherein one or more selected from the first sub-target, second sub-target or third sub-target has a target structure in a first layer at least partially overlapping a target structure in a second layer, wherein each of the first to third sub-targets is designed for a different set of process stack conditions for the substrate or is designed for a different layer-pair among three or more layers for overlay measurement, and wherein the beam spot is sized so as to cover at one time at least part of each of a periodic structure of the first to third sub-targets. - View Dependent Claims (15, 16, 17, 18, 19, 20)
Specification