System and method for lithography simulation
View Patent ↗There are many inventions described and illustrated herein. In one aspect, the present invention is directed to a technique of, and system for simulating, verifying, inspecting, characterizing, determining and/or evaluating the lithographic designs, techniques and/or systems, and/or individual functions performed thereby or components used therein. In one embodiment, the present invention is a system and method that accelerates lithography simulation, inspection, characterization and/or evaluation of the optical characteristics and/or properties, as well as the effects and/or interactions of lithographic systems and processing techniques. In this regard, in one embodiment, the present invention employs a lithography simulation system architecture, including application-specific hardware accelerators, and a processing technique to accelerate and facilitate verification, characterization and/or inspection of a mask design, for example, RET design, including detailed simulation and characterization of the entire lithography process to verify that the design achieves and/or provides the desired results on final wafer pattern. The system includes: (1) general purpose-type computing device(s) to perform the case-based logic having branches and inter-dependency in the data handling and (2) accelerator subsystems to perform a majority of the computation intensive tasks.
1. A method for evaluating a design pattern on a photolithographic mask, the method comprising:
generating a pixel-based bitmap of the design pattern on the photolithographic mask using an image of the photolithographic mask;
generating a simulated image of the design pattern in wafer resist using (1) the pixel-based bitmap of the design pattern on the photolithographic mask and (2) a relationship representing an imaging path of projection and illumination optics of a photolithographic tool; and
evaluating the design pattern on the photolithographic mask by comparing the simulated image of the design pattern in wafer resist and a design target on a wafer which corresponds to the design pattern on the photolithographic mask.
2. The method of claim 1 , wherein generating the simulated image of the design pattern in wafer resist further includes determining edge locations of the design pattern in wafer resist.
3. The method of claim 2 , wherein generating the simulated image of the design pattern in wafer resist further includes connecting edge points of the design pattern in wafer resist.
4. The method of claim 1 , wherein generating the simulated image of the design pattern in wafer resist further includes generating a three dimensional intensity distribution of the simulated image of the design pattern in wafer resist.
5. The method of claim 1 , wherein generating a simulated image of the design pattern in wafer resist further includes generating a two dimensional image distribution of the simulated image of the design pattern in wafer resist.
6. The method of claim 5 , wherein generating the two dimensional image distribution is representative of the simulated image of the design pattern in wafer resist at a predetermined distance from a surface of the wafer.
7. The method of claim 1 , wherein the pixel-based bitmap of the design pattern on the photolithographic mask includes pixel data, wherein each pixel datum represents a pixel having a predetermined pixel size.
8. The method of claim 7 , wherein the predetermined pixel size provides a sampling frequency that is greater than a Nyquist frequency in an image of the design pattern.
9. The method of claim 7 , wherein the predetermined pixel size is determined using a numerical aperture and wavelength of the projection optics of the photolithographic tool.
10. The method of claim 7 , wherein the design pattern on the photolithographic mask includes resolution enhancement technology.
11. The method of claim 1 , wherein the relationship representing the imaging path of the projection and illumination optics is a coefficient matrix representing the imaging path of the projection and illumination optics of the photolithographic tool.
12. The method of claim 11 , wherein the coefficient matrix representing the imaging path of the projection and illumination optics is representative of one or more of a focus, dose, numerical aperture, illumination aperture, and aberration of the photolithographic tool.
13. The method of claim 11 , wherein the coefficient matrix representing the imaging path of the projection and illumination optics of the photolithographic tool includes transmission cross coefficients.
14. The method of claim 1 , wherein generating a simulated image of the design pattern in wafer waist includes generating a simulated image of the design pattern in wafer resist using forward and backward Fast Fourier Transforms.
15. The method of claim 1 , wherein the relationship representing the imaging path of the projection and illumination optics of a photolithographic tool includes formulas using a focus, dose, numerical aperture, illumination aperture, and aberration of the photolithographic tool.
16. A system for evaluating a design pattern on a lithographic mask, the system comprising:
a microprocessor subsystem, including a plurality of microprocessors; and
a plurality of accelerator subsystems, each accelerator subsystem includes a plurality of programmable integrated circuits configured to process a pixel-based bitmap of the design pattern on the lithographic mask in parallel, and each accelerator subsystem is connected to an associated microprocessor to calculate a portion of a simulated image of the design pattern in wafer resist using (1) a corresponding portion of the pixel-based bitmap representation of the design pattern which is generated using an image of the lithographic mask and (2) a relationship representing an imaging path of projection and illumination optics of a photolithographic tool; and
a data processing system to compare the simulated image of the design pattern in wafer resist and a design target on a wafer which corresponds to the design pattern on the lithographic mask.
17. The system of claim 16 , wherein the pixel-based bitmap uses a predetermined pixel size, and the predetermined pixel size provides a sampling frequency that is greater than a Nyquist frequency in an image of the design pattern.
18. The system of claim 16 , wherein the pixel-based bitmap uses a predetermined pixel size, and wherein the predetermined pixel size is determined using a numerical aperture and wavelength of the projection optics of the photolithographic tool.
19. The system of claim 16 , wherein the accelerator subsystems further perform Fast Fourier Transforms, using pixel data, to generate a corresponding portion of the simulated image of the design pattern on the lithographic mask in wafer resist.
20. The system of claim 16 , wherein the relationship representing the imaging path of the projection and illumination optics includes a coefficient matrix representing the imaging path of the projection and illumination optics of the photolithographic tool.
21. The system of claim 20 , wherein the coefficient matrix representing the imaging path of the projection and illumination optics of the photolithographic tool is representative of one or more of a focus, dose, numerical aperture, illumination aperture, and aberration of the photolithographic tool.
22. The system of claim 20 , wherein the coefficient matrix representing the imaging path of the projection and illumination optics of the photolithographic tool are transmission cross coefficients.
23. The system of claim 16 , wherein the system further determines a set of parameters representing the imaging path of the projection and illumination optics of the photolithographic tool using one or more of a focus, dose, numerical aperture, illumination aperture, and aberration of the photolithographic tool.
24. The system of claim 16 , wherein the plurality of accelerator subsystems further calculate a three dimensional intensity distribution of the simulated image of the design pattern in wafer resist.
25. The system of claim 16 , wherein the plurality of accelerator subsystems further calculate a two dimensional image distribution of the simulated image of the design pattern in wafer resist.
26. The system of claim 25 , wherein the two dimensional image distribution is representative of an image of the design pattern in wafer resist at a predetermined distance from a surface of the wafer.
27. The system of claim 16 , wherein the accelerator subsystems further perform forward and backward Fast Fourier Transforms, using pixel data, to generate a corresponding portion of the simulated image of the design pattern in wafer resist.
28. A method for evaluating a design pattern on a lithographic mask, the method comprising:
generating a simulated image of the design pattern in wafer resist using (1) a pixel-based bitmap of the design pattern on the lithographic mask which is generated using an image of the lithographic mask and (2) a relationship representing an imaging path of projection and illumination optics of a photolithographic tool; and
evaluating a design pattern on a lithographic mask by comparing the simulated image of the design pattern in wafer resist and a design target on a wafer which corresponds to the design pattern on the lithographic mask.
29. The method of claim 28 , wherein generating the simulated image of the design pattern in wafer resist includes determining edge locations of the design pattern in wafer resist.
30. The method of claim 29 , wherein generating the simulated image of the design pattern in wafer resist includes connecting edge points of the design pattern in wafer resist.
31. The method of claim 28 , wherein generating the simulated image of the design pattern in wafer resist further includes generating a three dimensional intensity distribution of the simulated image of the design pattern in wafer resist.
32. The method of claim 28 , wherein generating the simulated image of the design pattern in wafer resist further includes generating a two dimensional image distribution of the simulated image of the design pattern in wafer resist at predetermined distance from a surface of a wafer.
33. The method of claim 28 , wherein the design pattern on the lithographic mask includes resolution enhancement technology.
34. The method of claim 28 , wherein the relationship representing the imaging path of the projection and illumination optics of a photolithographic tool includes one or more of a focus, dose, numerical aperture, illumination aperture, and aberration of the photolithographic tool.
35. The method of claim 28 , wherein the relationship representing the imaging path of the projection and illumination optics includes a coefficient matrix representing the imaging path of the projection and illumination optics of the photolithographic tool.
36. The method of claim 35 , wherein the coefficient matrix representing the imaging path of the projection and illumination optics of the photolithographic tool includes transmission cross coefficients.
37. The method of claim 35 , wherein the coefficient matrix representing the imaging path of the projection and illumination optics of the photolithographic tool is representative of one or more of a focus, dose, numerical aperture, illumination aperture, and aberration of the photolithographic tool.
38. The method of claim 28 , wherein generating a simulated image of the design pattern in wafer resist includes using Fast Fourier transforms.