Method, program product and apparatus for model based scattering bar placement for enhanced depth of focus in quarter-wavelength lithography
First Claim
1. A method, implemented by a computer, of improving imaging performance of a mask pattern having a feature to be imaged, said method comprising the steps of:
- (a) obtaining a model of a lithographic process for imaging said mask pattern onto a substrate;
(b) determining an optimal setting of said lithographic process to be utilized when imaging said mask pattern;
(c) determining, using said model, a first interference map based on said mask pattern and said optimal setting;
(d) determining a first seeding site representing the optimal placement of an assist feature within said mask pattern relative to said feature to be imaged on the basis of said first interference map;
(e) selecting a plurality of lithographic process settings that represent a predefined amount of variation relative to said optimal setting;
(f) determining, using said model, a plurality of interference maps respectively based on said mask pattern and said plurality of lithographic process settings;
(g) determining a plurality of seeding sites representing the optimal placement of an assist feature within said mask pattern relative to said feature to be imaged on the basis of said plurality of interference maps; and
(h) generating an assist feature having a shape which encompasses both said first seeding site and said plurality of seeding sites,wherein one or more of steps (a)-(f) are performed using said computer.
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Accused Products
Abstract
A method of generating a mask having optical proximity correction features. The method includes the steps of: (a) obtaining a desired target pattern having features to be imaged on a substrate; (b) determining a first focus setting to be utilized when imaging the mask; (c) determining a first interference map based on the target pattern and the first focus setting; (d) determining a first seeding site representing the optimal placement of an assist feature within the mask relative to a feature to be imaged on the basis of the first interference map; (e) selecting a second focus setting which represents a predefined amount of defocus relative to the first focus setting; (f) determining a second interference map based on the target pattern and the second focus setting; (g) determining a second seeding site representing the optimal placement of an assist feature within the mask relative to the feature to be imaged on the basis of the second interference map; and (h) generating an assist feature having a shape which encompasses both the first seeding site and the second seeding site.
32 Citations
19 Claims
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1. A method, implemented by a computer, of improving imaging performance of a mask pattern having a feature to be imaged, said method comprising the steps of:
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(a) obtaining a model of a lithographic process for imaging said mask pattern onto a substrate; (b) determining an optimal setting of said lithographic process to be utilized when imaging said mask pattern; (c) determining, using said model, a first interference map based on said mask pattern and said optimal setting; (d) determining a first seeding site representing the optimal placement of an assist feature within said mask pattern relative to said feature to be imaged on the basis of said first interference map; (e) selecting a plurality of lithographic process settings that represent a predefined amount of variation relative to said optimal setting; (f) determining, using said model, a plurality of interference maps respectively based on said mask pattern and said plurality of lithographic process settings; (g) determining a plurality of seeding sites representing the optimal placement of an assist feature within said mask pattern relative to said feature to be imaged on the basis of said plurality of interference maps; and (h) generating an assist feature having a shape which encompasses both said first seeding site and said plurality of seeding sites, wherein one or more of steps (a)-(f) are performed using said computer. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. A computer program product for controlling a computer comprising a non-transitory recording medium readable by the computer, means recorded on the recording medium for directing the computer to perform a method of improving imaging performance of a mask pattern having a feature to be imaged, said method comprising the steps of:
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(a) obtaining a model of a lithographic process for imaging said mask pattern onto a substrate; (b) determining an optimal setting of said lithographic process to be utilized when imaging said mask pattern; (c) determining, using said model, a first interference map based on said mask pattern and said optimal setting; (d) determining a first seeding site representing the optimal placement of an assist feature within said mask pattern relative to said feature to be imaged on the basis of said first interference map; (e) selecting a plurality of lithographic process settings that represent a predefined amount of variation relative to said optimal setting; (f) determining, using said model, a plurality of interference maps respectively based on said mask pattern and said plurality of lithographic process settings; (g) determining a plurality of seeding sites representing the optimal placement of an assist feature within said mask pattern relative to said feature to be imaged on the basis of said plurality of interference maps; and (h) generating an assist feature having a shape which encompasses both said first seeding site and said plurality of seeding sites. - View Dependent Claims (11, 12, 13, 14, 15, 16, 17, 18)
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19. A device manufacturing method comprising the steps of;
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(a) providing a substrate that is at least partially covered by a layer of radiation-sensitive material; (b) providing a projection beam of radiation using an imaging system; (c) using a mask pattern having a feature to be imaged to endow the projection beam with a pattern in its cross-section; (d) projecting the patterned beam of radiation onto a target portion of the layer of radiation-sensitive material, wherein, in step (c), said mask pattern is optimized by a method comprising the steps of; obtaining a model of said imaging system for imaging said mask pattern onto said substrate; determining an optimal setting of said imaging system to be utilized when imaging said mask pattern; determining, using said model, a first interference map based on said mask pattern and said optimal setting; determining a first seeding site representing the optimal placement of an assist feature within said mask pattern relative to said feature to be imaged on the basis of said first interference map; selecting a plurality of imaging system settings that represent a predefined amount of variation relative to said optimal setting; determining, using said model, a plurality of interference maps respectively based on said mask pattern and said plurality of imaging system settings; determining a plurality of seeding sites representing the optimal placement of an assist feature within said mask pattern relative to said feature to be imaged on the basis of said plurality of interference maps; and generating an assist feature having a shape which encompasses both said first seeding site and said plurality of seeding sites.
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Specification