Resolving phase-shift conflicts in layouts using weighted links between phase shifters

1. A method of assigning phases to shifters on a layout, the method comprising:

creating a link between any two shifters within a predetermined distance from each other, wherein a link corresponds to an indication that linked shifters are preferably assigned different phases;

assigning a weight to at least one link;

assigning phases to the shifters;

identifying whether a phase-shift conflict exists on the layout;

breaking a link based on its weight if a phase-shift conflict exists; and

reassigning phases to the shifters.

2. A method of assigning phases to shifters on a layout, the method comprising:

creating a link between any two shifters within a predetermined distance from each other, wherein a link corresponds to an indication that linked shifters are preferably assigned different phases;

assigning a weight to at least one link;

assigning phases to the shifters;

identifying whether a phase-shift conflict exists on the layout;

breaking a link based on its weight if a phase-shift conflict exists; and

breaking a plurality of links until the phase conflict is resolved.

3. The method of claim 2 , wherein the plurality of broken links have a different range of weights than any remaining links between shifters.

4. A method of assigning phases to shifters on a layout, the method comprising:

creating a link between any two shifters within a predetermined distance from each other, wherein a link corresponds to an indication that linked shifters are preferably assigned different phases;

assigning a weight to at least one link, wherein assigning a weight includes determining at least one dimension associated with each of the linked shifters;

assigning phases to the shifters;

identifying whether a phase-shift conflict exists on the layout; and

breaking a link based on its weight if a phase-shift conflict exists.

5. The method of claim 4 , wherein the at least one dimension includes an area.

6. A method of assigning phases to shifters on a layout, the method comprising:

creating a link between any two shifters within a predetermined distance from each other, wherein a link corresponds to an indication that linked shifters are preferably assigned different phases;

assigning a weight to at least one link, wherein assigning a weight includes determining an orientation of the linked shifters;

assigning phases to the shifters;

identifying whether a phase-shift conflict exists on the layout; and

breaking a link based on its weight if a phase-shift conflict exists.

7. The method of claim 6 , wherein the orientation includes a length over which the linked shifters are aligned.

8. A method of assigning phases to shifters on a layout, the method comprising:

creating a link between any two shifters within a predetermined distance from each other, wherein a link corresponds to an indication that linked shifters are preferably assigned different phases;

assigning a weight to at least one link, wherein assigning a weight includes determining whether a critical feature of the layout is located between the linked shifters;

assigning phases to the shifters;

identifying whether a phase-shift conflict exists on the layout; and

breaking a link based on its weight if a phase-shift conflict exists.

9. A method of assigning phases to shifters on a layout, the method comprising:

creating a link between any two shifters within a predetermined distance from each other, wherein a link corresponds to an indication that linked shifters are preferably assigned different phases;

assigning a weight to at least one link, wherein assigning a weight includes determining whether a non-critical feature of the layout is located between the linked shifters;

assigning phases to the shifters;

identifying whether a phase-shift conflict exists on the layout; and

breaking a link based on its weight if a phase-shift conflict exists.

10. A method of assigning phases to shifters on a layout, the method comprising:

creating a link between any two shifters within a predetermined distance from each other, wherein a link corresponds to an indication that linked shifters are preferably assigned different phases;

assigning a weight to at least one link, wherein assigning a weight includes determining whether a feature of the layout is located between the linked shifters;

assigning phases to the shifters;

identifying whether a phase-shift conflict exists on the layout; and

breaking a link based on its weight if a phase-shift conflict exists.

11. The method of claim 10 , wherein assigning a weight further includes determining a minimum distance from the feature to any proximate shifter.

12. The method of claim 10 , wherein assigning a weight includes identifying the feature by its type.

13. The method of claim 10 , wherein assigning a weight includes determining a size of the feature.

14. The method of claim 10 , wherein assigning a weight includes determining an association between the feature and another feature on another layout.

15. The method of claim 10 , wherein assigning a weight includes performing a simulation on the feature to determine critical dimension (CD) variations.

16. The method of claim 15 , wherein performing a simulation includes a first simulation assuming same phase assignment and a second simulation assuming opposite phase assignment.

17. A method of assigning phases to shifters on a layout, the method comprising:

creating a link between any two shifters within a predetermined distance from each other, wherein the predetermined distance is larger than a minimum feature size on the layout, wherein a link corresponds to an indication that linked shifters are preferably assigned different phases;

assigning a weight to at least one link;

assigning phases to the linked shifters;

identifying whether a phase-shift conflict exists on the layout; and

breaking a link based on its weight if a phase-shift conflict exists.

18. A method of assigning phases to shifters on a layout, the method comprising:

creating a link between any two shifters within a predetermined distance from each other, wherein the predetermined distance is smaller than a combined minimum pitch and regulator width on the layout, wherein a link corresponds to an indication that linked shifters are preferably assigned different phases;

assigning a weight to at least one link;

assigning phases to the shifters;

identifying whether a phase-shift conflict exists on the layout; and

breaking a link based on its weight if a phase-shift conflict exists.

19. A method of assigning phases to shifters on a layout, the method comprising:

creating a link between any two shifters within a predetermined distance from each other, wherein a link corresponds to an indication that linked shifters are preferably assigned different phases;

assigning a weight to at least one link;

assigning phases to the shifters;

identifying whether a phase-shift conflict exists on the layout; and

breaking a link based on its weight if a phase-shift conflict exists, wherein assigning phases occurs after identifying and breaking.

20. A method of assigning phases to shifters on a layout, the method comprising:

identifying a plurality of critical features on the layout, wherein each critical feature has a pair of associated shifters;

identifying any non-critical feature on the layout, wherein the non-critical feature is without a pair of associated shifters, but is located between two proximate shifters, and wherein the two proximate shifters are located within a predetermined distance of each other;

assigning phases to the pairs of associated shifters; and

minimizing phase-shift conflict between any of the two proximate shifters.

21. The method of claim 20 , further including:

creating a hard link between the pair of associated shifters, wherein a hard link indicates that the associated shifters have opposite phase; and

creating a soft link between the two proximate shifters, wherein a soft link indicates that the proximate shifters preferably have opposite phase.

22. The method of claim 21 , wherein creating a soft link includes providing a weight for each soft link.

23. The method of claim 22 , wherein minimizing phase-shift conflict includes breaking the soft link having one of a lowest weight and a highest weight.

24. A computer program product comprising:

a computer usable medium having a computer readable program code embodied therein for causing a computer to analyze a layout including a plurality of shifters and to resolve any phase-shift conflict on the layout, the computer readable program code comprising:

computer readable program code that creates a link between any two shifters within a predetermined distance from each other;

computer readable program code that assigns a weight to each link;

computer readable program code that assigns phases to linked shifters;

computer readable program code that identifies whether a phase-shift conflict exists on the layout; and

computer readable program code that breaks a link based on its weight, if a phase-shift conflict exists,

wherein the computer readable program code that assigns a weight to each link further includes:

computer readable program code that determines at least one of:

a distance between the linked shifters;

at least one dimension associated with each of the linked shifters;

an orientation of the linked shifters; and

whether a feature is located between the linked shifters.

25. A computer program product comprising:

a computer usable medium having a computer readable program code embodied therein for causing a computer to analyze a layout including a plurality of shifters and to resolve any phase-shift conflict on the layout, the computer readable program code comprising:

computer readable program code that creates a link between any two shifters within a predetermined distance from each other;

computer readable program code that assigns a weight to each link;

computer readable program code that assigns phases to linked shifters;

computer readable program code that identifies whether a phase-shift conflict exists on the layout; and

computer readable program code that breaks a link based on its weight, if a phase-shift conflict exists,

wherein the computer readable program code that determines whether a feature is located between the linked shifters further includes:

computer readable program code that determines a minimum distance from the feature to any proximate shifter.

26. A computer program product comprising:

a computer usable medium having a computer readable program code embodied therein for causing a computer to analyze a layout including a plurality of shifters and to resolve any phase-shift conflict on the layout, the computer readable program code comprising:

computer readable program code that creates a link between any two shifters within a predetermined distance from each other;

computer readable program code that assigns a weight to each link;

computer readable program code that assigns phases to linked shifters;

computer readable program code that identifies whether a phase-shift conflict exists on the layout; and

computer readable program code that breaks a link based on its weight, if a phase-shift conflict exists,

wherein the computer readable program code that determines whether a feature is located between the linked shifters further includes:

computer readable program code that identifies the feature by one of its type and its size.

27. A program storage device readable by a machine, tangibly embodying a program of instructions executable by said machine to perform method steps to analyze a mask used in lithography, the method comprising:

creating a link between any two shifters within a predetermined distance from each other;

assigning a weight to each link;

assigning phases to linked shifters;

identifying whether a phase-shift conflict exists on the layout;

breaking a link based on its weight, if a phase-shift conflict exists; and

reassigning phases to the linked shifters.

28. A program storage device readable by a machine, tangibly embodying a program of instructions executable by said machine to perform method steps to analyze a mask used in lithography, the method comprising:

creating a link between any two shifters within a predetermined distance from each other;

assigning a weight to each link;

assigning phases to linked shifters;

identifying whether a phase-shift conflict exists on the layout;

breaking a link based on its weight, if a phase-shift conflict exists; and

breaking a plurality of links until the phase conflict is resolved.

29. A program storage device readable by a machine, tangibly embodying a program of instructions executable by said machine to perform method steps to analyze a mask used in lithography, the method comprising:

creating a link between any two shifters within a predetermined distance from each other;

assigning a weight to each link;

assigning phases to linked shifters;

identifying whether a phase-shift conflict exists on the layout; and

breaking a link based on its weight, if a phase-shift conflict exists, wherein any broken links have a different range of weights than any remaining links between shifters.