Process for determination of optimized exposure conditions for transverse distortion mapping
First Claim
1. A process for providing illumination conditions for accurate determination of Zernike tilt coefficients in the presence of third-order coma for a lithographic projection system, the process comprising:
- selecting an optimized illumination condition;
performing a lens distortion test method using an optimized illumination condition selected from the determined illumination conditions;
constructing a lens distortion map in accordance with the collected illumination conditions and calculating Zernike tilt terms a2 and a3 in accordance with the lens distortion map such that the calculated Zernike tilt terms correspond to calculations in the absence of the effects of third-order coma for field positions of interest.
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Accused Products
Abstract
A process for providing illumination source conditions for the accurate determination Zernike tilt coefficients in the presence of coma is described. Large feature-shift coma sensitivity is simulated for a range of illumination conditions. The resulting source sensitivity data is modeled and a practical array of source shapes, each of which is optimized to eliminate the effects of transverse distortion due to third-order coma, is identified. The optimized set of source shapes can be used to more accurately determine Zernike terms a2 and a3 using a variety of methods. Knowledge of the lens distortion data in the absence of coma induced shifts can be entered into more traditional overlay regression routines to better identify systematic and random error. Additional applications of the above outlined procedure include: improved lithographic simulation using conventional optical modeling software and advanced process control in the form of feedback loops that automatically adjust the projection lens for optimum system performance.
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Citations
53 Claims
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1. A process for providing illumination conditions for accurate determination of Zernike tilt coefficients in the presence of third-order coma for a lithographic projection system, the process comprising:
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selecting an optimized illumination condition;
performing a lens distortion test method using an optimized illumination condition selected from the determined illumination conditions;
constructing a lens distortion map in accordance with the collected illumination conditions and calculating Zernike tilt terms a2 and a3 in accordance with the lens distortion map such that the calculated Zernike tilt terms correspond to calculations in the absence of the effects of third-order coma for field positions of interest. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16)
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17. A process for operating a lithographic projection imaging system, the process comprising:
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simulating a feature-shift in a scanning system of the lithographic projection imaging system in accordance with input parameters of interest and a range of illumination conditions;
determining illumination conditions within the range that significantly reduce large feature shifts that are due to third-order coma;
collecting the determined illumination conditions to enable the accurate determination of Zernike tilt coefficients;
performing a lens distortion test method using an optimized illumination condition selected from the determined illumination conditions;
constructing a lens distortion map in accordance with the collected illumination conditions and calculating Zernike tilt terms a2 and a3 in accordance with the lens distortion map such that the calculated Zernike tilt terms correspond to calculations in the absence of the effects of third-order coma for field positions of interest. - View Dependent Claims (18, 19, 20, 21)
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22. A projection lithography tool comprising:
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an illumination source;
a scanning system; and
a scanning system controller;
wherein a projection lens of the scanning system is adjusted by the scanning system controller in accordance with Zernike tilt coefficients determined by the controller after performing operations comprising;
selecting an optimized illumination condition;
performing a lens distortion test method using an optimized illumination condition selected from the determined illumination conditions;
constructing a lens distortion map in accordance with the collected illumination conditions and calculating Zernike tilt terms a2 and a3 in accordance with the lens distortion map such that the calculated Zernike tilt terms correspond to calculations in the absence of the effects of third-order coma for field positions of interest. - View Dependent Claims (23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37)
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38. A process for chip fabrication with a photolithographic projection imaging system, the process comprising:
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determining illumination conditions of the projection imaging system for accurate determination of Zernike tilt coefficients in the presence of third-order coma for a lithographic projection system by performing operations comprising selecting an optimized illumination condition, performing a lens distortion test method using an optimized illumination condition selected from the determined illumination conditions, and constructing a lens distortion map in accordance with the collected illumination conditions and calculating Zernike tilt terms a2 and a3 in accordance with the lens distortion map such that the calculated Zernike tilt terms correspond to calculations in the absence of the effects of third-order coma for field positions of interest;
controlling lithographic imaging in the system in accordance with the determined Zernike tilt coefficients; and
operating a chip producing process in accordance with the controlled lithographic imaging. - View Dependent Claims (39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53)
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Specification