Apparatus and method for separating a circuit pattern into multiple circuit patterns

• US 8,111,901 B2
• Filed: 08/14/2007
• Issued: 02/07/2012
• Est. Priority Date: 08/14/2006
• Status: Active Grant

• Current Assignee: ASML Netherlands BV (ASML Holding NV)
• Original Assignee: ASML Masktools B.V. (ASML Holding NV)
• Inventors: Nikolsky, Peter
• Primary Examiner(s): Lu, Tom Y
• Application Number:
  US11/889,573
• Publication Number:
  US 20080037861A1
• Time in Patent Office: 1,638 Days
• Field of Search: 382/141, 382/147
• US Class Current: 382/147
• CPC Class Codes: G03F 7/70283 Mask effects on the imaging process
• CPC Class Codes: G03F 7/70433 Layout for increasing efficiency or for compensating imaging errors, e.g. layout of exposure fields for reducing focus errors; Use of mask features for increasing efficiency or for compensating imaging errors
• CPC Class Codes: G03F 7/70466 Multiple exposures, e.g. combination of fine and coarse exposures, double patterning or multiple exposures for printing a single feature stitching G03F7/70475
• CPC Class Codes: G03F 7/705 Modelling or simulating from physical phenomena up to complete wafer processes or whole workflow in wafer productions
• CPC Class Codes: G06V 30/422 Technical drawings; Geographical maps

Abstract

A method for separating an original circuit pattern to be printed on a wafer, into multiple circuit patterns is disclosed. Simulation to obtain an image log-slope (ILS), normalized image log-slope (NILS), or any other characteristic of an image quality on edges of polygons in the circuit pattern obtained from circuit pattern data is performed. Properly printed edges and not-properly printed edges are identified according to a criterion of an ILS level. The original circuit pattern is separated into multiple circuit patterns such that each of the multiple patterns does not have any not-properly printed edges.

Claims

1. A method for separating an original circuit pattern to be printed on a wafer via a lithography process, into multiple circuit patterns, comprising the steps of:

obtaining circuit pattern data;

identifying a model of the lithography process;

performing a simulation of the lithography process using the model to obtain image quality information on edges of polygons in the circuit pattern based on the circuit pattern data;

identifying edges that are expected to be printed properly and edges that are expected to be printed improperly on the wafer according to the image quality information obtained from the simulation; and

separating the original circuit pattern into multiple circuit patterns such that each of the multiple patterns does not have any improperly printed edges.

2. The method according to claim 1, wherein the separating step includes:

selecting a first polygon with a first improperly printed edge among the polygons, and finding at least one second polygon with a second not-properly printed edge opposing to the first improperly printed edge;

determining whether the second polygon can be separated from the first polygon based on a topological criterion; and

separating the second polygon from the first polygon when it is determined that the second polygon can be separated.

3. The method according to claim 2, wherein the performing step, the identifying step, and the separating step including the selecting, determining, and separating steps are executed in that order until no polygon with a improperly printed edge is found in the original circuit pattern.

4. The method according to claim 3, wherein the topological criterion at least causes the determining step to determine whether there are one first improperly printed edge and 2n second improperly printed edges (n:

integer), and these edges are opposed to each other, and when the topological criterion is met, the separating step does not separate the second polygon from the first polygon.

5. The method according to claim 3, wherein the selecting step selects a third polygon with a third improperly y printed edge, the third improperly printed edge having been opposed to the separated second polygon, and finding a fourth polygon with a fourth improperly printed edge opposing to the third improperly printed edge of the third polygon,

the determining step determines whether the fourth polygon can be separated from the third polygon based on the topological criterion, and

the separating step separates the fourth polygon from the third polygon when it is determined that the fourth polygon can be separated.

6. The method according to claim 5, wherein the selecting step selects any of polygons with a not-printed edge as the first polygon when no third polygon exists.

7. The method according to claim 1, wherein the image quality information is one of an image log-slope (ILS) and a normalized image log-slope (NILS).

8. An apparatus for separating, using a computer processor, an original circuit pattern to be printed on a wafer via a lithography process, into multiple circuit patterns, comprising:

a first unit in the computer processor configured for performing a simulation of the lithography process using a model of the lithography process to obtain image quality information on edges of polygons in the circuit pattern obtained from circuit pattern data;

a second unit in the computer processor configured for identifying edges that are expected to be printed properly and edges that are expected to be printed improperly on the wafer according to the image quality information obtained from the simulation; and

a third unit in the computer processor configured for separating the original circuit pattern into multiple circuit patterns such that each of the multiple patterns does not have any improperly printed edges.

9. The apparatus according to claim 8, wherein the third unit in the computer processor is further configured for selecting a first polygon with a first improperly printed edge among the polygons, and finding at least one second polygon with a second improperly printed edge opposing to the first improperly printed edge;

determining whether the second polygon can be separated from the first polygon based on a topological criterion; and

separating the second polygon from the first polygon when it is determined that the second polygon can be separated.

10. The apparatus according to claim 9, wherein the performing of the simulation, the identifying of the edges, the selecting of the first polygons, the finding of the second polygons, the determining whether the second polygon can be separated, and the separating of the second polygon are executed in that order until no polygon with a improperly printed edge is found in the original circuit pattern.

11. The apparatus according to claim 10, wherein the topological criterion at least causes the third unit in the computer processor to determine whether there are one first improperly printed edge and 2n second improperly printed edges (n:

integer), and these edges are opposed to each other, and when the topological criterion is met, the third unit does not separate the second polygon from the first polygon.

12. The apparatus according to claim 10, wherein the third unit in the computer processor is further configured for

selecting a third polygon with a third improperly printed edge, the third improperly printed edge having been opposed to the separated second polygon, and finding a fourth polygon with a fourth improperly printed edge opposing to the third improperly printed edge of the third polygon,

determining whether the fourth polygon can be separated from the third polygon based on the topological criterion, and

separating the fourth polygon from the third polygon when it is determined that the fourth polygon can be separated.

13. The apparatus according to claim 12, wherein the third unit in the computer processor selects any of polygons with a not-printed edge as the first polygon when no third polygon exists.

14. The apparatus according to claim 8, wherein the image quality information is one of an image log-slope (ILS) and a normalized image log-slope (NILS).

15. A non-transitory computer readable storage medium storing a computer program for separating an original circuit pattern to be printed on a wafer via a lithography process, into multiple circuit patterns, when executed, causing a computer to perform the steps of:

obtaining circuit pattern data;

identifying a model of the lithography process;

performing simulation of the lithography process using the model to obtain image quality information on edges of polygons in the circuit pattern based on the circuit pattern data;

identifying edges that are expected to be printed properly and edges that are expected to be printed improperly on the wafer according to the image quality information obtained from the simulation; and

separating the original circuit pattern into multiple circuit patterns such that each of the multiple patterns does not have any improperly printed edges.

16. The non-transitory computer readable storage medium according to claim 15, wherein the separating step includes:

selecting a first polygon with a first improperly printed edge among the polygons, and finding at least one second polygon with a second improperly printed edge opposing to the first improperly printed edge;

determining whether the second polygon can be separated from the first polygon based on a topological criterion; and

separating the second polygon from the first polygon when it is determined that the second polygon can be separated.

17. The non-transitory computer readable storage medium according to claim 15, wherein the performing step, the identifying step, and the separating step including the selecting, determining, and separating steps are executed in that order until no polygon with a improperly printed edge is found in the original circuit pattern.

18. The non-transitory computer readable storage medium according to claim 17, wherein the topological criterion at least causes the determining step to determine whether there are one first improperly printed edge and 2n second improperly printed edges (n:

integer), and these edges are opposed to each other, and

when the topological criterion is met, the separating step does not separate the second polygon from the first polygon.

19. The non-transitory computer readable storage medium according to claim 17, wherein the selecting step selects a third polygon with a third improperly printed edge, the third improperly printed edge having been opposed to the separated second polygon, and finding a fourth polygon with a fourth improperly printed edge opposing to the third improperly printed edge of the third polygon,

the determining step determines whether the fourth polygon can be separated from the third polygon based on the topological criterion, and

the separating step separates the fourth polygon from the third polygon when it is determined that the fourth polygon can be separated.

20. The non-transitory computer readable storage medium according to claim 19, wherein the selecting step selects any of polygons with a not-printed edge as the first polygon when no third polygon exists.

21. The non-transitory computer readable storage medium according to claim 15, wherein the image quality information is one of an image log-slope (ILS) and a normalized image log-slope (NILS).

22. A device manufacturing method using a lithography process 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 patterns on masks to endow the projection beam with patterns 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), providing a pattern on a mask includes the steps of;

performing a simulation of the lithography process using a model of the lithography process to obtain image quality information on edges of polygons in a circuit pattern obtained from circuit pattern data;

identifying edges that are expected to be printed properly and printed edges that are expected to be printed improperly on the wafer according to the image quality information obtained from the simulation; and

separating the original circuit pattern into multiple circuit patterns to be assigned to the masks, respectively, such that each of the multiple patterns does not have any improperly printed edges.