Retargeting based on process window simulation

1. A method of retargeting, comprising:

performing, using a computer, a process window simulation on a layout design to generate process window information;

selecting edge fragments for retargeting in the layout design, wherein the selecting edge fragments comprises identifying simulations sites; and connecting pairs of the simulation sites with CD (critical dimension) gauges according to one or more rules;

adjusting targeted positions of the edge fragments to generate retargeted positions in a balanced way based on the process window information; and

storing the retargeted positions.

2. The method recited in claim 1 , wherein one of the one or more rules is selecting a pair of simulation sites to be connected with a CD gauge only if the distance between the pair of simulation sites is within a predefined range.

3. The method recited in claim 1 , wherein one of the one or more rules is selecting simulation site for a CD gauge only if the angle between the simulation site and the normal to an achievable target for an edge fragment associated with the simulation site is less than a predefined value.

4. The method recited in claim 1 , wherein one of the one or more rules is selecting a pair of simulation sites to be connected with a CD gauge only if the angle between the pair of simulation sites is less than a predefined value.

5. The method recited in claim 1 , wherein the simulation sites comprises simulation sites used in an OPC process.

6. The method recited in claim 5 , wherein the simulation sites further comprises simulation sites added according to one or more criteria.

7. The method recited in claim 6 , wherein one of the one or more criteria is that a simulation site should be added to an edge fragment that is near the middle of an enclosed shape if no such a simulation site exists for the edge fragment.

8. A method of retargeting, comprising:

performing, using a computer, a process window simulation on a layout design to generate process window information;

selecting edge fragments for retargeting in the layout design;

adjusting targeted positions of the edge fragments to generate retargeted positions in a balanced way based on the process window information, wherein the adjusting targeted positions comprises balancing forces acting on the edge fragments, the forces being derived based on totally or partially on the process window information, wherein the forces include CD gauge forces, restoring forces, and if an enclosed shape is involved, enclosure forces; and

storing the retargeted positions.

9. The method recited in claim 8 , wherein the forces further include forces related to edge placement error (EPE) tolerances.

10. A processor-readable device storing processor-executable instructions for causing one or more processors to perform retargeting by the following steps:

performing a process window simulation on a layout design to generate process window information;

selecting edge fragments for retargeting in the layout design, wherein the selecting edge fragments comprises identifying simulations sites; and connecting pairs of the simulation sites with CD gauges according to one or more rules;

adjusting targeted positions of the edge fragments to generate retargeted positions in a balanced way based on the process window information; and

storing the retargeted positions.

11. A processor-readable device storing processor-executable instructions for causing one or more processors to perform retargeting by the following steps:

performing a process window simulation on a layout design to generate process window information;

selecting edge fragments for retargeting in the layout design;

adjusting targeted positions of the edge fragments to generate retargeted positions in a balanced way based on the process window information, wherein the adjusting targeted positions comprises balancing forces acting on the edge fragments, the forces being derived based on totally or partially on the process window information, wherein the forces include CD gauge forces, restoring forces, and if an enclosed shape is involved, enclosure forces; and

storing the retargeted positions.

12. The processor-readable device recited in claim 11 , wherein the forces further include forces related to edge placement error (EPE) tolerances.

13. A system comprising one or more processors, the one or more processors programmed to perform retargeting by the following steps:

performing a process window simulation on a layout design to generate process window information;

selecting edge fragments for retargeting in the layout design, wherein the selecting edge fragments comprises identifying simulations sites; and connecting pairs of the simulation sites with CD gauges according to one or more rules;

adjusting targeted positions of the edge fragments to generate retargeted positions in a balanced way based on the process window information; and

storing the retargeted positions.

14. A system comprising one or more processors, the one or more processors programmed to perform retargeting by the following steps:

performing a process window simulation on a layout design to generate process window information;

selecting edge fragments for retargeting in the layout design;

adjusting targeted positions of the edge fragments to generate retargeted positions in a balanced way based on the process window information, wherein the adjusting targeted positions comprises balancing forces acting on the edge fragments, the forces being derived based on totally or partially on the process window information, wherein the forces include CD gauge forces, restoring forces, and if an enclosed shape is involved, enclosure forces; and

storing the retargeted positions.

15. The system recited in claim 14 , wherein the forces further include forces related to edge placement error (EPE) tolerances.