Fast freeform source and mask co-optimization method
First Claim
1. A computer-implemented method for optimizing a lithographic process in a simulation domain, the simulated lithographic process having data representing an illumination source and a mask, the method comprising:
- performing, by the computer, a free-form optimization process;
placing, by the computer, sub-resolution assist feature (SRAF) seeds in a description of the mask based on a result of the free-form optimization process; and
performing, by the computer, a constrained optimization process, including growing the SRAF seeds while taking into account manufacturability constraints for both the illumination source and the mask.
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Abstract
The present disclosure relates to lithographic apparatuses and processes, and more particularly to tools for optimizing illumination sources and masks for use in lithographic apparatuses and processes. According to certain aspects, the present disclosure significantly speeds up the convergence of the optimization by allowing direct computation of gradient of the cost function. According to other aspects, the present disclosure allows for simultaneous optimization of both source and mask, thereby significantly speeding the overall convergence. According to still further aspects, the present disclosure allows for free-form optimization, without the constraints required by conventional optimization techniques.
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Citations
16 Claims
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1. A computer-implemented method for optimizing a lithographic process in a simulation domain, the simulated lithographic process having data representing an illumination source and a mask, the method comprising:
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performing, by the computer, a free-form optimization process; placing, by the computer, sub-resolution assist feature (SRAF) seeds in a description of the mask based on a result of the free-form optimization process; and performing, by the computer, a constrained optimization process, including growing the SRAF seeds while taking into account manufacturability constraints for both the illumination source and the mask. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. A computer program product comprising a non-transitory computer readable medium having instructions recorded thereon, the instructions, when executed by a computer, implements a method for optimizing a lithographic process in a simulation domain, the simulated lithographic process having data representing an illumination source and a mask, the method comprising:
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performing a free-form optimization process; placing sub-resolution assist feature (SRAF) seeds in a description of the mask based on a result of the free-form optimization process; and performing a constrained optimization process, including growing the SRAF seeds while taking into account manufacturability constraints for both the illumination source and the mask. - View Dependent Claims (10, 11, 12, 13, 14, 15, 16)
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Specification