Iterative method for refining integrated circuit layout using compass optical proximity correction (OPC)
View Patent ↗The present invention is an iterative method or procedure involving a series of optical proximity correction (OPC) process steps for refining an integrated circuit design layout on a wafer during a photolithographic process. The iterative method may be applied as a system and computer program to perform classifying and grouping edge fragments according to directional orientations, selecting an edge fragment or a combination of non-opposing edge fragments, calculating an edge placement error of the selected edge fragment and proximally shifting the edge fragment until a quality limitation is met.
1. A system for refining an integrated circuit (IC) layout through an iterative procedure, the IC layout having of a plurality edge fragments, the system comprising:
means for determining a directional orientation of each edge fragment;
means for grouping edge fragments of the same directional orientation to form mutually exclusive directional orientation sets;
means for selecting an edge fragment from one of the mutually exclusive sets;
means for calculating an edge placement error (EPE) of the selected edge fragments;
means for shifting the selected edge fragment based on the calculated EPE to a new position;
means for updating the orientation of the shifted edge fragment;
means for selecting an edge fragment from another one of the mutually exclusive sets;
means for reiterating calculating the EPE of the edge fragment, shifting edge fragment and updating orientation and selecting of an edge of a different directional orientation until a predetermined limit is reached
wherein the means for reiterating calculating the EPE of the edge fragment performs the calculating by alternating between mutually exclusive sets; and
wherein the mutually exclusive sets contain edge fragments of non-opposing directional orientation.
2. The system of claim 1 , wherein each of the mutually exclusive directional orientation sets is selected from a group consisting of: top, bottom, left and right.
3. The system of claim 1 , wherein each of the mutually exclusive directional orientation sets, defined by an angle, α, is selected from a group consisting of: 0°≦α<90°, 90°≦α<225°, 225°≦α<270° and 270°≦α<360°.
4. The system of claim 1 , wherein the means for grouping of edge fragments further performs combining at least two mutually exclusive directional orientation sets, wherein the at least two mutually exclusive directional orientation sets include edge fragments of non-opposing directional orientations.
5. The system of claim 4 , wherein each of the combined mutually exclusive directional orientation sets is selected from a group consisting of: top-left, bottom-right, top-right and bottom-left.
6. The system of claim 4 , wherein each of the mutually exclusive directional orientation sets, defined by an angle, α, is selected from a group consisting of: 0°≦α<180° and 180°≦α<360°.
7. The system of claim 4 , wherein calculating means calculates the EPE of the selected edge fragment and further incorporates an EPE from an edge fragment of opposing directional orientation.
8. A computer program stored on a machine-readable storage device, for refining an integrated circuit (IC) layout, the IC layout comprising a plurality of edge fragments, the computer program including executable program code for: determining a directional orientation of each edge fragment;
grouping edge fragments of the same directional orientation to form mutually exclusive directional orientation sets;
selecting an edge fragment from one of the mutually exclusive sets;
calculating an edge placement error (EPE) of the selected edge fragments;
shifting the selected edge fragment based on the calculated EPE to a new position;
updating the orientation of the shifted edge fragment;
selecting an edge fragment from another one of the mutually exclusive sets;
reiterating calculating the EPE of the edge fragment, shifting edge fragment and updating orientation and selecting of an edge of a different directional orientation to attain a predetermined limit;
wherein the reiterating calculating the EPE of the edge fragment alternates between mutually exclusive sets; and
wherein the mutually exclusive sets contain edge fragments of non-opposing directional orientation.
9. The computer program of claim 8 , wherein each of the mutually exclusive directional orientation sets is selected from a group consisting of: top, bottom, left and right.
10. The computer program of claim 8 , wherein each of the mutually exclusive directional orientation sets, defined by an angle, α, is selected from a group consisting of: 0°≦α<90°, 90°≦α<180°, 180°≦α<270° and 270°≦α<360°.
11. The computer program of claim 8 , further comprising combining at least two mutually exclusive directional orientation sets, wherein the at least two mutually exclusive directional orientation sets include edge fragments of non-opposing directional orientations.
12. The computer program of claim 11 , wherein each of the combined mutually exclusive directional orientation sets is selected from a group consisting of: top-left, bottom-right, top-right and bottom-left.
13. The computer program of claim 11 , wherein each of the mutually exclusive directional orientation sets, defined by an angle, α, is selected from a group consisting of: 0°≦α<180° and 180°≦α<360°.