Pattern-dependent proximity matching/tuning including light manipulation by projection optics
AssigneeASML Netherlands B.V.
InventorsHanying Feng, Yu Cao, Jun Ye
Life of this patent
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Abstract
Described herein are methods for matching the characteristics of a lithographic projection apparatus to a reference lithographic projection apparatus, where the matching includes optimizing projection optics characteristics. The projection optics can be used to shape wavefront in the lithographic projection apparatus. According to the embodiments herein, the methods can be accelerated by using linear fitting algorithm or using Taylor series expansion using partial derivatives of transmission cross coefficients (TCCs).
Claims20
A computer-implemented method for improving imaging performance of a lithographic apparatus, the method comprising:
- obtaining initial values of one or more design variables that control an optical wavefront shape of the lithographic apparatus, at least some of the design variables comprising characteristics of a projection optics system included in the lithographic apparatus;
- obtaining a known pattern to be imaged using the lithographic apparatus;
- defining a multi-variable cost function of the one or more design variables, wherein the cost function is indicative of the imaging performance at predefined evaluation points on the known pattern;
- and
- updating, using the computer, the initial values of the one or more design variables based on a numerical convergence technique to optimize the multi-variable cost function, wherein the updated values of the one or more design variables shape the optical wavefront to produce an image of the known pattern that matches an imaging performance of a reference lithographic apparatus.
A computer program product comprising a non-transitory computer-readable medium having machine executable instructions, the instructions being executable by a machine to perform a method for improving imaging performance of a lithographic apparatus, the method comprising:
- obtaining initial values of one or more design variables that control an optical wavefront shape of the lithographic apparatus, at least some of the design variables comprising characteristics of a projection optics system included in the lithographic apparatus;
- obtaining a known pattern to be imaged using the lithographic apparatus;
- defining a multi-variable cost function of the one or more design variables, wherein the cost function is indicative of the imaging performance at predefined evaluation points on the known pattern;
- and
- updating the initial values of the one or more design variables based on a numerical convergence technique to optimize the multi-variable cost function, wherein the updated values of the one or more design variables shape the optical wavefront to produce an image of the known pattern that matches an imaging performance of a reference lithographic apparatus.
Dependencies are inferred from the claim text.