MODEL-BASED SCANNER TUNING SYSTEMS AND METHODS
First Claim
1. A method for tuning a lithographic apparatus using a corresponding model, comprising:
- maintaining a lithographic process model characterizing the imaging behavior of the lithographic process for a given layer of a wafer using the lithographic apparatus, subject to changes in a set of tunable parameters on the lithographic apparatus;
generating simulated wafer contour in the given layer using a design layout and the lithographic process model;
identifying discrepancies in the simulated wafer contour against a reference;
quantifying the discrepancies with a cost function; and
performing iterations of the generating and identifying steps to minimize the cost function and obtain a desired degree of convergence of the simulated wafer contour with the reference, wherein at least one tunable parameter of the lithographic apparatus is adjusted prior to performing each iteration.
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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.
45 Citations
15 Claims
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1. A method for tuning a lithographic apparatus using a corresponding model, comprising:
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maintaining a lithographic process model characterizing the imaging behavior of the lithographic process for a given layer of a wafer using the lithographic apparatus, subject to changes in a set of tunable parameters on the lithographic apparatus; generating simulated wafer contour in the given layer using a design layout and the lithographic process model; identifying discrepancies in the simulated wafer contour against a reference; quantifying the discrepancies with a cost function; and performing iterations of the generating and identifying steps to minimize the cost function and obtain a desired degree of convergence of the simulated wafer contour with the reference, wherein at least one tunable parameter of the lithographic apparatus is adjusted prior to performing each iteration. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15)
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Specification