Method, program product and apparatus for model based geometry decomposition for use in a multiple exposure process

Abstract

A method of decomposing a target pattern having features to be imaged on a substrate so as to allow said features to be imaged in a multi-exposure process. The method includes the steps of: (a) segmenting a plurality of the features into a plurality of polygons; (b) determining the image log slope (ILS) value for each of the plurality of polygons; (c) determining the polygon having the minimum ILS value, and defining a mask containing the polygon; (d) convolving the mask defined in step (c) with an eigen function of a transmission cross coefficient so as to generate an interference map, where the transmission cross coefficient defines the illumination system to be utilized to image the target pattern; and (e) assigning a phase to the polygon based on the value of the interference map at a location corresponding to the polygon, where the phase defines which exposure in said multi-exposure process the polygon is assigned.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an exemplary flowchart illustrating the model based coloring process of the present invention, which is utilized to decompose a target pattern into multiple segments, which are then utilized in a multiple illumination process.

FIG. 2 illustrates an exemplary target pattern that will be decomposed into multiple segments utilizing the coloring process of the present invention.

FIG. 3 illustrates Step 12 of the coloring process of the present invention, in which fragmentation points are defined.

FIG. 4 illustrates Step 14 of the coloring process, in which multiple polygons are defined based on the fragmentation points defined in Step 12.

FIG. 5 illustrates Step 18 of the coloring process, in which a mask is defined which comprises the single polygon having the lowest ILS.

FIG. 6 illustrates Step 20 of the coloring process, in which an interference map is defined for the single polygon defined in Step 18.

FIG. 7 illustrates how the areas of the target mask would be defined into separate exposures based on the interference map illustrated in FIG. 6.

FIG. 8 illustrates Step 26 of the coloring process, in which a mask containing the polygon with the next highest cost function within a predefined coherence radius is defined.

FIG. 9 illustrates Step 30 of the coloring process, in which an interference map representing the combination of the single polygon having the lowest ILS and the polygon select in Step 26 is defined.

FIG. 10 illustrates how the areas of the target mask would be defined into separate exposures based on the interference map illustrated in FIG. 9.

FIG. 11 illustrates the total interference map after all polygons have been processed.

FIG. 12 illustrates how the areas of the target mask would be defined into separate exposures based on the interference map illustrated in FIG. 11.

FIG. 13 illustrates a second exemplary target pattern.

FIG. 14 illustrates the interference generated by the process of the present invention corresponding to the target pattern of FIG. 13.

FIG. 15 illustrates how the areas of the target mask would be defined into separate exposures based on the interference map illustrated in FIG. 14.

FIG. 16 is a block diagram that illustrates a computer system which can implement illumination optimization according to an embodiment of the present invention.

FIG. 17 schematically depicts an exemplary lithographic projection apparatus suitable for use with a mask designed with the aid of the disclosed concepts.

Claims

1. A method of decomposing a target pattern having features to be imaged on a substrate so as to allow said features to be imaged in a multi-exposure process, said method comprising the steps of: (a) segmenting a plurality of said features into a plurality of polygons;(b) determining the image log slope (ILS) value for each of said plurality of polygons;(c) determining the polygon having the minimum ILS value, and defining a mask containing said polygon;(d) convolving said mask defined in step (c) with an eigen function of a transmission cross coefficient so as to generate a first interference map, said transmission cross coefficient defining an illumination system; and(e) assigning a phase to said polygons based on the value of the first interference map at a location respectively corresponding to said polygons, said phase defining which exposure in said multi-exposure process said polygons are assigned.

2. The method of decomposing a target pattern according to claim 1, further comprising the steps of: (f) selecting another polygon, and defining a mask containing said polygon;(g) convolving said mask defined in step (f) with said eigen function of said transmission cross coefficient so as to generate a second interference map;(h) generate a total interference map by combining said first interference map and said second interference map; and(i) assigning a phase to said polygons based on the value of the total interference map at a location respectively corresponding to said polygons, said phase defining which exposure in said multi-exposure process said polygons are assigned;wherein said steps (f)-(i) are repeated until all polygons have been processed.

3. The method of decomposing a target pattern according to claim 2, wherein step (f) comprises ranking the polygons utilizing a cost function, and the polygon having the highest cost function is selected as the next polygon for processing.

4. The method of decomposing a target pattern according to claim 2, wherein said polygons are assigned either a first phase or a second phase, said polygons assigned said first phase are to be imaged in a first exposure process and said polygons assigned said second phase are to be imaged in a second exposure process.

5. The method of decomposing a target pattern according to claim 4, wherein each polygon having a positive value in the corresponding location of the total interference map is assigned said first phase, and each polygon having a negative value in the corresponding location of the total interference map is assigned said second phase.

6. The method of decomposing a target pattern according to claim 2, wherein a single feature contained in said target pattern can be decomposed into multiple segments which are assigned different phases and which are to be imaged in different exposure processes.

7. A computer program product for controlling a computer comprising a recording medium readable by the computer, means recorded on the recording medium for directing the computer to decompose a target pattern having features to be imaged on a substrate so as to allow said features to be imaged in a multi-exposure process, the process comprising the steps of: (a) segmenting a plurality of said features into a plurality of polygons;(b) determining the image log slope (ILS) value for each of said plurality of polygons;(c) determining the polygon having the minimum ILS value, and defining a mask containing said polygon;(d) convolving said mask defined in step (c) with an eigen function of a transmission cross coefficient so as to generate a first interference map, said transmission cross coefficient defining an illumination system; and(e) assigning a phase to said polygons based on the value of the first interference map at a location respectively corresponding to said polygons, said phase defining which exposure in said multi-exposure process said polygons are assigned.

8. The computer program product of claim 7, wherein said process further comprising the steps of: (f) selecting another polygon, and defining a mask containing said polygon;(g) convolving said mask defined in step (f) with said eigen function of said transmission cross coefficient so as to generate a second interference map;(h) generate a total interference map by combining said first interference map and said second interference map; and(i) assigning a phase to said polygons based on the value of the total interference map at a location respectively corresponding to said polygons, said phase defining which exposure in said multi-exposure process said polygons are assigned;wherein said steps (f)-(i) are repeated until all polygons have been processed.

9. The computer program product of claim 8, wherein step (f) comprises ranking the polygons utilizing a cost function, and the polygon having the highest cost function is selected as the next polygon for processing.

10. The computer program product of claim 8, wherein said polygons are assigned either a first phase or a second phase, said polygons assigned said first phase are to be imaged in a first exposure process and said polygons assigned said second phase are to be imaged in a second exposure process.

11. The computer program product of claim 10, wherein each polygon having a positive value in the corresponding location of the total interference map is assigned said first phase, and each polygon having a negative value in the corresponding location of the total interference map is assigned said second phase.

12. The computer program product of claim 8, wherein a single feature contained in said target pattern can be decomposed into multiple segments which are assigned different phases and which are to be imaged in different exposure processes.

13. A device manufacturing method comprising the steps of: (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 pattern on a mask 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 is formed by a method comprising the steps of:(e) segmenting a plurality of said features into a plurality of polygons;(f) determining the image log slope (ILS) value for each of said plurality of polygons;(g) determining the polygon having the minimum ILS value, and defining a mask containing said polygon;(h) convolving said mask defined in step (g) with an eigen function of a transmission cross coefficient so as to generate a first interference map, said transmission cross coefficient defining an illumination system; and(i) assigning a phase to said polygons based on the value of the first interference map at a location respectively corresponding to said polygons, said phase defining which exposure in said multi-exposure process said polygons are assigned.

14. A method of decomposing a target pattern having features to be imaged on a substrate so as to allow said features to be imaged in a multi-exposure process, said method comprising the steps of: (a) segmenting a plurality of said features into a plurality of polygons; and(b) assigning a phase or color to said polygons based on the value of an interference map at a location respectively corresponding to said polygons, said phase or color defining which exposure in said multi-exposure process said polygons are assigned.

15. The method of claim 14, wherein said interference map is generated by convolving a mask representing said polygons with an eigen function of a transmission cross coefficient, said transmission cross coefficient defining an illumination system.

16. A method of decomposing a target pattern having features to be imaged on a substrate so as to allow said features to be imaged in a multi-exposure process, said method comprising the steps of: (a) segmenting a plurality of said features into a plurality of polygons; and(b) assigning a phase or color to said polygons based on the result of a convolution of a mask representing said polygons with an eigen function of a transmission cross coefficient, said transmission cross coefficient defining an illumination system.

17. A mask formed utilizing the method of claim 1.

18. A mask formed utilizing the method of claim 14.

19. A mask formed utilizing the method of claim 16.

20. A method of imaging a wafer comprising the steps of: (a) segmenting a plurality of features to be imaged into a plurality of polygons; and(b) assigning a phase or color to said polygons based on the value of an interference map at a location respectively corresponding to said polygons, said phase or color defining which exposure in a multi-exposure process said polygons are assigned.

21. The method of claim 20, wherein said interference map is generated by convolving a mask representing said polygons with an eigen function of a transmission cross coefficient, said transmission cross coefficient defining an illumination system.

22. A method of imaging a wafer comprising the steps of: (a) segmenting a plurality of features to be imaged into a plurality of polygons; and(b) assigning a phase or color to said polygons based on the result of a convolution of a mask representing said polygons with an eigen function of a transmission cross coefficient, said transmission cross coefficient defining an illumination system.

23. A computer program product for controlling a computer comprising a recording medium readable by the computer, means recorded on the recording medium for directing the computer to decompose a target pattern having features to be imaged on a substrate so as to allow said features to be imaged in a multi-exposure process, the process comprising the steps of: (a) segmenting a plurality of said features into a plurality of polygons; and(b) assigning a phase or color to said polygons based on the value of an interference map at a location respectively corresponding to said polygons, said phase or color defining which exposure in said multi-exposure process said polygons are assigned.

24. The computer program product of claim 23, wherein said interference map is generated by convolving a mask representing said polygons with an eigen function of a transmission cross coefficient, said transmission cross coefficient defining an illumination system.

25. A computer program product for controlling a computer comprising a recording medium readable by the computer, means recorded on the recording medium for directing the computer to decompose a target pattern having features to be imaged on a substrate so as to allow said features to be imaged in a multi-exposure process, the process comprising the steps of: (a) segmenting a plurality of said features into a plurality of polygons; and(b) assigning a phase or color to said polygons based on the result of a convolution of a mask representing said polygons with an eigen function of a transmission cross coefficient, said transmission cross coefficient defining an illumination system.