Method, program product and apparatus of simultaneous optimization for NA-Sigma exposure settings and scattering bars OPC using a device layout
Disclose is a method, program product and apparatus for optimizing numerical aperture (“NA”) and sigma of a lithographic system based on the target layout. A pitch or interval analysis is performed to identify the distribution of critical pitch over the design. Based on the pitch or interval analysis, a critical dense pitch is identified. NA, sigma-in, sigma-out parameters are optimized such that the critical feature will print with or without bias adjustment. For features other than the critical dense features, adjustments are made in accordance with OPC, and lithographic apparatus settings are further mutually optimized. Accordingly, lithographic apparatus settings may be optimized for any pattern concurrently with OPC.
1. A method of optimizing lithographic apparatus settings and optimizing optical proximity correction (OPC) for a pattern to be formed on a surface of a substrate, said method comprising the steps of:
(a) identifying a critical dense pitch corresponding to a first critical feature and a second critical feature;
(b) determining optimal lithographic apparatus settings for the first critical feature;
(c) performing OPC based on an analysis of the first critical feature;
(d) performing OPC adjustments on the second critical feature; and
(e) optimizing lithographic apparatus settings for the second critical feature.
2. The method according to claim 1 , wherein lithographic settings comprise numerical aperture of a lens and sigma of an illuminator.
3. The method according to claim 1 , further comprising the step of repeating steps (d) and (e) for a plurality of critical features until OPC adjustments satisfy a predetermined criteria.
4. The method according to claim 1 , further comprising the steps of:
(f) identifying a plurality of intervals or a plurality of pitches of a design;
(g) categorizing like intervals of the plurality of intervals or like pitches of the plurality of pitches; and
(h) determining an interval or a pitch with the most occurrences.
5. A computer program product on a machine readable medium comprising executable code transportable by at least one machine readable medium, wherein execution of the code by at least one programmable computer causes the at least one programmable computer to perform a sequence of steps for optimizing lithographic apparatus settings and optimizing optical proximity correction (OPC) for a pattern to be formed on a surface of a substrate, comprising the steps of:
(a) identifying a critical dense pitch corresponding to a first critical feature and a second critical feature;
(b) determining optimal lithographic apparatus settings for the first critical feature;
(c) performing OPC based on an analysis of the first critical feature;
(d) performing OPC adjustments on the second critical feature; and
(e) optimizing lithographic apparatus settings for the second critical feature.
6. The computer program product according to claim 5 , wherein lithographic settings comprise numerical aperture of a lens and sigma in and sigma_out setting of an illuminator.
7. The computer program product according to claim 5 , further comprising the step of repeating steps (d) and (e) for a plurality of critical features until OPC adjustments are sufficient.
8. The computer program product according to claim 5 , further comprising the steps of:
(f) identifying a plurality of intervals or a plurality of pitches of a design;
(g) categorizing like intervals of the plurality of intervals or like pitches of the plurality of pitches; and
(h) determining an interval or a pitch with the most occurrences.
9. An apparatus optimizing lithographic apparatus settings and optimizing optical proximity correction (OPC) for a pattern to be formed on a surface of a substrate, said apparatus comprising:
a radiation system for supplying a projection beam;
an illuminator for receiving the projection beam of radiation and projecting an adjusted beam of radiation on a portion of a mask, wherein the illuminator has preset sigma-outer and preset sigma-inner parameters, and
a projection system having a numerical aperture (“NA”) for imaging a corresponding irradiated portion of a mask, onto a target portion of the substrate,
wherein
NA, preset sigma-outer, and preset sigma-inner and OPC are mutually optimized for a plurality of critical features of the pattern.
10. The apparatus according to claim 9 , further comprising:
a computer system configured to determine the preset NA, preset sigma-outer and preset sigma-inner parameters by the steps comprising:
(a) identifying a critical dense pitch corresponding to a first critical feature and a second critical feature;
(b) determining optimal lithographic apparatus settings for the first critical feature;
(c) performing OPC based on an analysis of the first critical feature;
(d) performing OPC adjustments on the second critical feature; and
(e) optimizing lithographic apparatus settings for the second critical feature.
11. The apparatus according to claim 10 , further comprising the step of repeating steps (d) and (e) for a plurality of non-critical features until OPC adjustments are sufficient.