Apparatus and methods for detecting overlay errors using scatterometry
First Claim
Patent Images
1. A combined scatterometry mark, comprising:
- a scatterometry critical dimension (CD) or profile target capable of being measured to determine CD or profile information; and
a scatterometry overlay target disposed over the scatterometry CD or profile target, the scatterometry overlay target and the scatterometry CD or profile target together forming a scatterometry mark capable of being measured to determine overlay based on a scatterometry overlay technique without using calibration or a model regression technique,wherein the scatterometry overlay technique is a phase based technique that includes representing each measured optical signal as a set of periodic functions having a plurality of known parameters and an unknown overlay error parameter and analyzing the set of periodic functions to solve for the unknown overlay error parameter to thereby determine the overlay error.
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Abstract
Disclose is a combined scatterometry mark comprising a scatterometry critical dimension (CD) or profile target capable of being measured to determine CD or profile information and a scatterometry overlay target disposed over the scatterometry CD or profile target, the scatterometry overlay target cooperating with the scatterometry CD or profile target to form a scatterometry mark capable of being measured to determine overlay.
160 Citations
15 Claims
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1. A combined scatterometry mark, comprising:
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a scatterometry critical dimension (CD) or profile target capable of being measured to determine CD or profile information; and a scatterometry overlay target disposed over the scatterometry CD or profile target, the scatterometry overlay target and the scatterometry CD or profile target together forming a scatterometry mark capable of being measured to determine overlay based on a scatterometry overlay technique without using calibration or a model regression technique, wherein the scatterometry overlay technique is a phase based technique that includes representing each measured optical signal as a set of periodic functions having a plurality of known parameters and an unknown overlay error parameter and analyzing the set of periodic functions to solve for the unknown overlay error parameter to thereby determine the overlay error. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. A method of producing a combined critical dimension and overlay mark, comprising:
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forming a scatterometry critical dimension (CD) or profile target capable of being measured to determine CD or profile information; forming a scatterometry overlay target disposed over the scatterometry CD or profile target, the scatterometry overlay target and the scatterometry CD or profile target together forming a scatterometry mark capable of being measured to determine overlay based on a scatterometry overlay technique without using calibration or a model regression technique; measuring the scatterometry CD or profile target to determine CD or profile information; and measuring the scatterometry mark using the scatterometry technique to determine overlay, wherein the scatterometry overlay technique is a phase based technique that includes representing each measured optical signal as a set of periodic functions having a plurality of known parameters and an unknown overlay error parameter and analyzing the set of periodic functions to solve for the unknown overlay error parameter to thereby determine the overlay error.
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10. A method for determining CD in one layer and an overlay error between at least two layers in a multiple layer sample, the method comprising:
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performing scatterometry measurements on a CD target in order to determine CD, the CD target being formed in a first layer of the sample; performing scatterometry measurements on an overlay mark, the overlay mark comprising the CD target formed in the first layer and an overlay target formed in a second layer disposed over the CD target of the first layer; and determining and storing an overlay error using a scatterometry overlay technique that is based on the scatterometry measurements that are performed on the overlay mark without using a calibration or model-based regression technique, wherein the scatterometry overlay technique is a phase based technique that includes representing each measured optical signal as a set of periodic functions having a plurality of known parameters and an unknown overlay error parameter and analyzing the set of periodic functions to solve for the unknown overlay error parameter to thereby determine the overlay error. - View Dependent Claims (11, 12, 13, 14, 15)
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Specification