Method of predicting and minimizing model OPC deviation due to mix/match of exposure tools using a calibrated Eigen decomposition model

1. A method for generating models for simulating the imaging performance of a plurality of exposure tools, said method comprising the steps of:

generating a calibrated model for a first exposure tool, said calibrated model capable of estimating an image to be produced by said first exposure tool for a given photolithography process, said calibrated model comprising a first set of basis functions;

generating a model of a second exposure tool, said model capable of estimating an image to be produced by said second exposure tool for said photolithography process, said model comprising a second set of basis functions; and

representing said second set of basis functions as a linear combination of said first set of basis functions so as to generate an equivalent model function corresponding to said second exposure tool,

wherein said equivalent model function produces a simulated image corresponding to the image generated by said second exposure tool for said photolithography process.

2. The method of claim 1 , wherein said calibrated model is generated by:

defining parameters of said first exposure tool and processing conditions to be utilized in said photolithography process;

generating an initial model of said first exposure tool;

defining a plurality of test structures;

imaging the test structures utilizing said first exposure tool and processing conditions of said photolithography process to obtain actual imaging results;

generating simulated imaging results by subjecting said test structures to said initial model;

comparing said simulated imaging results to said actual imaging results; and

adjusting said initial model such that the difference between said simulated imaging results and said actual imaging results is less than a predefined criteria,

wherein said adjusted initial model corresponds to said calibrated model.

3. The method of claim 1 , wherein said first set of basis functions and said second set of basis functions comprise a plurality of eigen functions.

4. The method of claim 1 , wherein there is no calibration process performed on said second exposure tool.

5. The method of claim 2 , wherein said comparing said simulated imaging results to said actual imaging results utilizes two-dimensional contour patterns in the comparison process.

6. A computer readable medium having stored thereon a computer program having executable code, wherein execution of the code by at least one programmable computer causes the at least one programmable computer to perform a sequence of steps for generating models for simulating the imaging performance of a plurality of exposure tools, said sequence of steps comprising:

generating a calibrated model for a first exposure tool, said calibrated model capable of estimating an image to be produced by said first exposure tool for a given photolithography process, said calibrated model comprising a first set of basis functions;

generating a model of a second exposure tool, said model capable of estimating an image to be produced by said second exposure tool for said photolithography process, said model comprising a second set of basis functions; and

representing said second set of basis functions as a linear combination of said first set of basis functions so as to generate an equivalent model function corresponding to said second exposure tool,

wherein said equivalent model function produces a simulated image corresponding to the image generated by said second exposure tool for said photolithography process.

7. The computer readable medium of claim 6 , wherein said step of generating said calibrated model comprises the steps of:

defining parameters of said first exposure tool and processing conditions to be utilized in said photolithography process;

generating an initial model of said first exposure tool;

defining a plurality of test structures;

imaging the test structures utilizing said first exposure tool and processing conditions of said photolithography process to obtain actual imaging results;

generating simulated imaging results by subjecting said test structures to said initial model;

comparing said simulated imaging results to said actual imaging results; and

adjusting said initial model such that the difference between said simulated imaging results and said actual imaging results is less than a predefined criteria,

wherein said adjusted initial model corresponds to said calibrated model.

8. The computer readable medium of claim 6 , wherein said first set of basis functions and said second set of basis functions comprise a plurality of eigen functions.

9. The computer readable medium of claim 6 , wherein there is no calibration process performed on said second exposure tool.

10. The computer readable medium of claim 7 , wherein said comparing said simulated imaging results to said actual imaging results utilizes two-dimensional contour patterns in the comparison process.

11. An apparatus for generating models for simulating the imaging performance of a plurality of exposure tools, said apparatus comprising:

means for generating a calibrated model for a first exposure tool, said calibrated model capable of estimating an image to be produced by said first exposure tool for a given photolithography process, said calibrated model comprising a first set of basis functions;

means for generating a model of a second exposure tool, said model capable of estimating an image to be produced by said second exposure tool for said photolithography process, said model comprising a second set of basis functions; and

means for representing said second set of basis functions as a linear combination of said first set of basis functions so as to generate an equivalent model function corresponding to said second exposure tool,

wherein said equivalent model function produces a simulated image corresponding to the image generated by said second exposure tool for said photolithography process.

12. The apparatus of claim 11 , wherein said means for generating said calibrated model comprises:

means for defining parameters of said first exposure tool and processing conditions to be utilized in said photolithography process;

means for generating an initial model of said first exposure tool;

means for defining a plurality of test structures;

means for imaging the test structures utilizing said first exposure tool and processing conditions of said photolithography process to obtain actual imaging results;

means for generating simulated imaging results by subjecting said test structures to said initial model;

means for comparing said simulated imaging results to said actual imaging results; and

means for adjusting said initial model such that the difference between said simulated imaging results and said actual imaging results is less than a predefined criteria,

wherein said adjusted initial model corresponds to said calibrated model.

13. The apparatus of claim 11 , wherein said first set of basis functions and said second set of basis functions comprise a plurality of eigen functions.

14. The apparatus of claim 11 , wherein there is no calibration process performed on said second exposure tool.

15. The apparatus of claim 12 , wherein said comparing said simulated imaging results to said actual imaging results utilizes two-dimensional contour patterns in the comparison process.