Model-based scanner tuning systems and methods
First Claim
1. A method implemented by a computer, the method being for tuning a lithographic apparatus using a corresponding differential model that predicts changes in imaging behavior due to changes between two or more lithographic apparatuses, the method comprising:
- maintaining a lithographic process model characterizing imaging behavior of a lithographic process for a given layer of a wafer using one of the lithographic apparatuses, given particular values for a set of tunable parameters on the one lithographic apparatus;
generating a simulated wafer contour in the given layer using a design layout and the lithographic process model based on the particular values of the set of tunable parameters;
identifying discrepancies in the simulated wafer contour against a reference corresponding to the particular values of the set of tunable parameters and a different one of the lithographic apparatuses;
quantifying the discrepancies with a cost function; and
performing iterations of the generating and identifying steps to minimize the cost function and obtain calibrated parameters of the differential model, wherein each iteration uses a different reference corresponding to a different one of the lithographic apparatuses,wherein one or more of the maintaining, generating, identifying, quantifying and performing steps are implemented by the computer.
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Abstract
Systems and methods for tuning photolithographic processes are described. A model of a target scanner is maintained defining sensitivity of the target scanner with reference to a set of tunable parameters. A differential model represents deviations of the target scanner from the reference. The target scanner may be tuned based on the settings of the reference scanner and the differential model. Performance of a family of related scanners may be characterized relative to the performance of a reference scanner. Differential models may include information such as parametric offsets and other differences that may be used to simulate the difference in imaging behavior.
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Citations
26 Claims
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1. A method implemented by a computer, the method being for tuning a lithographic apparatus using a corresponding differential model that predicts changes in imaging behavior due to changes between two or more lithographic apparatuses, the method comprising:
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maintaining a lithographic process model characterizing imaging behavior of a lithographic process for a given layer of a wafer using one of the lithographic apparatuses, given particular values for a set of tunable parameters on the one lithographic apparatus; generating a simulated wafer contour in the given layer using a design layout and the lithographic process model based on the particular values of the set of tunable parameters; identifying discrepancies in the simulated wafer contour against a reference corresponding to the particular values of the set of tunable parameters and a different one of the lithographic apparatuses; quantifying the discrepancies with a cost function; and performing iterations of the generating and identifying steps to minimize the cost function and obtain calibrated parameters of the differential model, wherein each iteration uses a different reference corresponding to a different one of the lithographic apparatuses, wherein one or more of the maintaining, generating, identifying, quantifying and performing steps are implemented by the computer. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13)
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14. A non-transitory computer readable storage medium having instructions stored thereon, which when executed by a computer, cause the computer to implement a method, the method being for tuning a lithographic apparatus using a corresponding differential model that predicts changes in imaging behavior due to changes between two or more lithographic apparatuses, the method comprising:
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maintaining a lithographic process model characterizing imaging behavior of a lithographic process for a given layer of a wafer using one of the lithographic apparatuses, given particular values for a set of tunable parameters on the one lithographic apparatus; generating a simulated wafer contour in the given layer using a design layout and the lithographic process model based on the particular values of the set of tunable parameters; identifying discrepancies in the simulated wafer contour against a reference corresponding to the particular values of the set of tunable parameters and a different one of the lithographic apparatuses; quantifying the discrepancies with a cost function; and performing iterations of the generating and identifying steps to minimize the cost function and obtain calibrated parameters of the differential model, wherein each iteration uses a different reference corresponding to a different one of the lithographic apparatuses, wherein one or more of the maintaining, generating, identifying, quantifying and performing steps are implemented by the computer. - View Dependent Claims (15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26)
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Specification