Determining multi-patterning step overlay error
First Claim
1. A system configured to determine overlay error between different patterned features of a design printed on a wafer in a multi-patterning step process, comprising:
- an output acquisition subsystem comprising at least an energy source and a detector, wherein the energy source is configured to generate energy that is directed to a wafer, wherein the detector is configured to detect energy from the wafer and to generate output responsive to the detected energy, wherein first and second patterned features are printed on a level of the wafer with first and second patterning steps, respectively, and wherein a design for the level of the wafer comprises a design for the first patterned features and a design for the second patterned features; and
one or more computer subsystems configured for;
aligning the design for the level of the wafer to an image for the wafer generated from the output by aligning the design for the first patterned features to the first patterned features in the image thereby aligning all of the design for the level to the first patterned features;
shifting only the design for the second patterned features from a position of the design for the second patterned features, determined by said aligning all of the design, to a shifted position of the design for the second patterned features by aligning only the design for the second patterned features to only the second patterned features in the image; and
determining an offset between the position of the design for the second patterned features and the shifted position of the design for the second patterned features, wherein the offset is equal to relative overlay error between the first patterned features on the wafer and the second patterned features on the wafer.
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Abstract
Methods and systems for determining overlay error between different patterned features of a design printed on a wafer in a multi-patterning step process are provided. For multi-patterning step designs, the design for a first patterning step is used as a reference and designs for each of the remaining patterning steps are synthetically shifted until the synthetically shifted designs have the best global alignment with the entire image based on global image-to-design alignment. The final synthetic shift of each design for each patterning step relative to the design for the first patterning step provides a measurement of relative overlay error between any two features printed on the wafer using multi-patterning technology.
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Citations
22 Claims
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1. A system configured to determine overlay error between different patterned features of a design printed on a wafer in a multi-patterning step process, comprising:
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an output acquisition subsystem comprising at least an energy source and a detector, wherein the energy source is configured to generate energy that is directed to a wafer, wherein the detector is configured to detect energy from the wafer and to generate output responsive to the detected energy, wherein first and second patterned features are printed on a level of the wafer with first and second patterning steps, respectively, and wherein a design for the level of the wafer comprises a design for the first patterned features and a design for the second patterned features; and one or more computer subsystems configured for; aligning the design for the level of the wafer to an image for the wafer generated from the output by aligning the design for the first patterned features to the first patterned features in the image thereby aligning all of the design for the level to the first patterned features; shifting only the design for the second patterned features from a position of the design for the second patterned features, determined by said aligning all of the design, to a shifted position of the design for the second patterned features by aligning only the design for the second patterned features to only the second patterned features in the image; and determining an offset between the position of the design for the second patterned features and the shifted position of the design for the second patterned features, wherein the offset is equal to relative overlay error between the first patterned features on the wafer and the second patterned features on the wafer. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20)
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21. A non-transitory computer-readable medium, storing program instructions executable on a computer system for performing a computer-implemented method for determining overlay error between different patterned features of a design printed on a wafer in a multi-patterning step process, wherein the computer-implemented method comprises:
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aligning a design for a level of a wafer to an image for the wafer generated from output generated by an output acquisition system comprising at least an energy source and a detector, wherein the energy source is configured to generate energy that is directed to a wafer, wherein the detector is configured to detect energy from the wafer and to generate output responsive to the detected energy, wherein first and second patterned features are printed on the level of the wafer with first and second patterning steps, respectively, wherein a design for the level of the wafer comprises a design for the first patterned features and a design for the second patterned features, and wherein said aligning comprises aligning the design for the first patterned features to the first patterned features in the image thereby aligning all of the design for the level to the first patterned features; shifting only the design for the second patterned features from a position of the design for the second patterned features, determined by said aligning all of the design, to a shifted position of the design for the second patterned features by aligning only the design for the second patterned features to only the second patterned features in the image; and determining an offset between the position of the design for the second patterned features and the shifted position of the design for the second patterned features, wherein the offset is equal to relative overlay error between the first patterned features on the wafer and the second patterned features on the wafer, and wherein said aligning, said shifting, and said determining are performed by the computer system.
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22. A computer-implemented method for determining overlay error between different patterned features of a design printed on a wafer in a multi-patterning step process, comprising:
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aligning a design for a level of a wafer to an image for the wafer generated from output generated by an output acquisition system comprising at least an energy source and a detector, wherein the energy source is configured to generate energy that is directed to a wafer, wherein the detector is configured to detect energy from the wafer and to generate output responsive to the detected energy, wherein first and second patterned features are printed on the level of the wafer with first and second patterning steps, respectively, wherein a design for the level of the wafer comprises a design for the first patterned features and a design for the second patterned features, and wherein said aligning comprises aligning the design for the first patterned features to the first patterned features in the image thereby aligning all of the design for the level to the first patterned features; shifting only the design for the second patterned features from a position of the design for the second patterned features, determined by said aligning all of the design, to a shifted position of the design for the second patterned features by aligning only the design for the second patterned features to only the second patterned features in the image; and determining an offset between the position of the design for the second patterned features and the shifted position of the design for the second patterned features, wherein the offset is equal to relative overlay error between the first patterned features on the wafer and the second patterned features on the wafer, and wherein said aligning, said shifting, and said determining are performed by one or more computer systems.
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Specification