Model-based process simulation systems and methods
First Claim
1. A method for simulating contours produced by a lithographic process for a design, wherein the method is implemented by a computer, the method comprising:
- maintaining a differential model that defines differences in imaging results obtained when using a second lithographic process from imaging results obtained when using a different first lithographic process, wherein the differences in imaging results are attributable to differences in lithographic process parameters between the second lithographic process and the different first lithographic process; and
generating, using the computer and the differential model, a predicted difference in simulated wafer contours for the second lithographic process, wherein the predicted difference is a difference between simulated wafer contours respectively produced by the first and second lithographic processes for the design.
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Abstract
Systems and methods for process simulation are described. The methods may use a reference model identifying sensitivity of a reference scanner to a set of tunable parameters. Chip fabrication from a chip design may be simulated using the reference model, wherein the chip design is expressed as one or more masks. An iterative retuning and simulation process may be used to optimize critical dimension in the simulated chip and to obtain convergence of the simulated chip with an expected chip. Additionally, a designer may be provided with a set of results from which an updated chip design is created.
27 Citations
18 Claims
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1. A method for simulating contours produced by a lithographic process for a design, wherein the method is implemented by a computer, the method comprising:
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maintaining a differential model that defines differences in imaging results obtained when using a second lithographic process from imaging results obtained when using a different first lithographic process, wherein the differences in imaging results are attributable to differences in lithographic process parameters between the second lithographic process and the different first lithographic process; and generating, using the computer and the differential model, a predicted difference in simulated wafer contours for the second lithographic process, wherein the predicted difference is a difference between simulated wafer contours respectively produced by the first and second lithographic processes for the design. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
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12. A method for calibrating a lithographic model, wherein the method is implemented by a computer, the method comprising:
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performing a plurality of simulations of a lithographic process, wherein for each simulation, tunable settings of a process model are changed; comparing simulated contours produced by the simulations with measured contours produced under corresponding changes in the lithographic process to identify differences between the simulated contours and the measured contours; and calibrating, using the computer, parameters of the process model using a cost function based on the identified differences, wherein the process model describes differences in imaging results when using a second set of tunable settings of the lithographic process, wherein the differences in imaging results are attributable to differences in lithographic process parameters between the second set of tunable settings of the lithographic process and a different first set of tunable settings of the lithographic process. - View Dependent Claims (13)
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14. A method for calibrating a lithographic model, wherein the method is implemented by a computer, the method comprising:
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performing simulations of a lithographic process for a plurality of scanners, wherein a differential model characterizes scanner related differences in the lithographic process; identifying differences between simulated contours produced by the simulations and corresponding measured contours obtained from the plurality of scanners under the simulated conditions; and optimizing, using the computer, parameters of the differential model based on the identified differences, wherein the differential model describes differences in imaging results when using a second one of the scanners, wherein the differences in imaging results are attributable to differences in lithographic process parameters between the second scanner and a different first one of the scanners. - View Dependent Claims (15, 16, 17, 18)
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Specification