Method and apparatus to determine a patterning process parameter
A method including: obtaining a detected representation of radiation redirected by each of a plurality of structures from a substrate additionally having a device pattern thereon, wherein each structure has an intentional different physical configuration of the respective structure than the respective nominal physical configuration of the respective structure, wherein each structure has geometric symmetry at the respective nominal physical configuration, wherein the intentional different physical configuration of the structure causes an asymmetric optical characteristic distribution and wherein a patterning process parameter measures change in the physical configuration; and determining a value, based on the detected representations and based on the intentional different physical configurations, to setup, monitor or correct a measurement recipe for determining the patterning process parameter.
1. A patterning device pattern comprising:
a device pattern; and
a metrology target pattern separate from the device pattern for formation of a metrology target for setup, monitoring or correction of a measurement recipe used to determine a patterning process parameter that measures change in a physical configuration of a structure based on a detected representation of radiation redirected by the structure, wherein the structure has geometric symmetry at a nominal physical configuration and wherein a different physical configuration of the structure than the nominal physical configuration causes an asymmetric optical characteristic distribution, the metrology target pattern comprising patterns corresponding to each of a plurality of target structures to be formed on the substrate using the patterns, wherein each target structure has an intentional different physical configuration of the respective target structure than the respective nominal physical configuration of the respective target structure, wherein each target structure has geometric symmetry at the respective nominal physical configuration, wherein the intentional different target structure physical configuration of the respective target structure causes an asymmetric optical characteristic distribution and wherein the patterning process parameter measures change in the target structure physical configuration from the intentional and/or nominal target structure physical configuration and wherein each target structure is configured to enable a value of the patterning process parameter to be determined from that target structure without use of radiation from another of the target structures.
2. The patterning device pattern of claim 1 , wherein the patterns corresponding to the target structures form at least part of one or more design of experiment (DoE) target areas at the substrate, each DoE target area corresponding to one or more particular types of the same patterning process parameter.
3. The patterning device pattern of claim 2 , wherein the patterns corresponding to the target structures form at least part of a plurality of DoE target areas at the substrate, each DoE target area corresponding to a different set of one or more types of the same patterning process parameter.
4. The patterning device pattern of claim 1 , wherein the metrology target at the substrate has an area of less than or equal to about 2500 μm 2 .
5. The patterning device pattern of claim 1 , wherein the patterning process parameter comprises overlay.
6. The patterning device pattern of claim 5 , wherein the target structures have different configurations corresponding to at least three types of overlay.
7. A metrology target for setup, monitoring or correction of a measurement recipe used to determine a patterning process parameter that measures change in a physical configuration of a structure based on a detected representation of radiation redirected by the structure, wherein the structure has geometric symmetry at a nominal physical configuration and wherein a different physical configuration of the structure than the nominal physical configuration causes an asymmetric optical characteristic distribution in the detected representation, the metrology target comprising:
a plurality of target areas, wherein each target area has a target structure that has an intentional different physical configuration of the respective target structure than the respective nominal physical configuration of the respective target structure, wherein each target structure has geometric symmetry at the respective nominal physical configuration, wherein the intentional different physical configuration of the respective target structure causes an asymmetric optical characteristic distribution and wherein each target area is associated with a different type of a certain same patterning process parameter, each patterning process parameter type measuring a respective change in the target structure physical configuration of the associated target structure from the intentional and/or nominal target structure physical configuration and wherein each target structure is configured to enable a value of the respective patterning process parameter type to be determined from that target structure without use of radiation from another of the target structures.
8. The metrology target of claim 7 , wherein at least one target area comprises a plurality of sub-targets, each sub-target having a different variation in the physical configuration of its respective structure.
9. The metrology target of claim 7 , wherein the target areas are arranged in a grid.
10. The metrology target of claim 7 , having an area of less than or equal to about 2500 μm 2 .
11. The metrology target of claim 7 , wherein at least one structure of the plurality of target areas has a continuous variation in the intentional different physical configuration of the respective structure.
12. The metrology target of claim 7 , wherein the patterning process parameter comprises overlay.
13. The metrology target of claim 12 , wherein the plurality of target areas have different configurations corresponding to at least three types of overlay.
14. A method comprising:
exposing a device pattern on a substrate; and
exposing, onto the substrate, a metrology target pattern separate from the device pattern for formation of a metrology target for setup, monitoring or correction of a measurement recipe used to determine a patterning process parameter that measures change in a physical configuration of a structure based on a detected representation of radiation redirected by the structure, wherein the structure has geometric symmetry at a nominal physical configuration and wherein a different physical configuration of the structure than the nominal physical configuration causes an asymmetric optical characteristic distribution, the metrology target pattern comprising patterns corresponding to each of a plurality of target structures to be formed on the substrate using the patterns, wherein each target structure has an intentional different physical configuration of the respective structure than the respective nominal physical configuration of the respective target structure, wherein each target structure has geometric symmetry at the respective nominal physical configuration, wherein the intentional different target structure physical configuration of the respective target structure causes an asymmetric optical characteristic distribution and wherein the patterning process parameter measures change in the target structure physical configuration from the intentional and/or nominal target structure physical configuration and wherein each target structure is configured to enable a value of the patterning process parameter to be determined from that target structure without use of radiation from another of the target structures.
15. The method of claim 14 , wherein the patterns corresponding to the target structures form at least part of one or more design of experiment (DoE) target areas at the substrate, each DoE target area corresponding to one or more particular types of the same patterning process parameter.
16. The method of claim 15 , wherein the patterns corresponding to the target structures form at least part of a plurality of DoE target areas at the substrate, each DoE target area corresponding to a different set of one or more types of the same patterning process parameter.
17. The method of claim 14 , wherein the metrology target at the substrate has an area of less than or equal to about 2500 μm 2 .
18. The method of claim 14 , wherein the patterning process parameter comprises overlay.
19. The method of claim 18 , wherein the target structures have different configurations corresponding to at least three types of overlay.
20. The method of claim 14 , wherein the device pattern and metrology target pattern are part of a patterning device pattern exposed together as part of a scanning exposure.