Projection Exposure System Illumination Stress Management
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Solution Overview
Problem
Projection exposure systems for microlithography face challenges with high surface energy densities in pupil planes, leading to material damage and inflexibility due to the need to adjust radiant power for each illumination setting, which restricts throughput and flexibility.
Innovation Solution
A method to automatically determine illumination stress on optical elements and adjust the radiant power of the light source accordingly, using variably adjustable pupil-defining elements and recording usage history to set optimal radiant power and prevent damage, allowing for flexible operation and extended system lifetime.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If oblique incident light illumination settings are used to achieve high resolution, then manufacturing precision is improved, but surface energy density increases causing material damage
Solution Approach 1:
The patent implements dynamic adjustment of the illumination system's numerical aperture based on the specific illumination setting being used. The system automatically adapts the NA to match the requirements of each illumination mode (annular, dipole, quadrupole), thereby optimizing resolution while minimizing excess energy concentration that would otherwise damage optical elements.
Solution Approach 2:
The system changes the numerical aperture parameter dynamically according to the selected illumination setting. By adjusting this key optical parameter, the system achieves the optimal balance between resolution (manufacturing precision) and energy distribution (surface energy density), preventing material damage while maintaining high-quality patterning.
2Reliability
If radiant power is reduced to prevent material damage, then reliability is improved, but throughput decreases
Solution Approach 1:
The system dynamically adjusts the numerical aperture to match each illumination setting, which optimizes the energy distribution across optical elements. This allows the system to maintain high radiant power for maximum throughput while preventing excessive energy concentration that would cause material damage, thereby simultaneously improving reliability and maintaining productivity.
Solution Approach 2:
The system incorporates feedback mechanisms that monitor the illumination setting and automatically adjust the numerical aperture accordingly. This closed-loop control ensures that the optimal NA is always applied, allowing high radiant power to be used safely and efficiently, thus maintaining both reliability and throughput.
3Reliability
If radiant power is adjusted for each illumination setting to prevent damage, then reliability is improved, but device complexity increases
Solution Approach 1:
The system implements a dynamic NA adjustment mechanism that is automatically triggered by the selection of different illumination settings. This automated dynamic adjustment eliminates the need for complex manual calibration and power adjustment procedures for each setting, thereby maintaining reliability while actually reducing operational complexity.
Solution Approach 2:
The illumination system is designed to automatically adjust its own numerical aperture based on the selected illumination mode. This self-service capability eliminates the need for external intervention or complex control systems, simplifying the overall device architecture while ensuring reliable operation across all illumination settings.
4Productivity
If fixed radiant power is used to maintain throughput, then productivity is improved, but optical elements suffer cumulative damage
Solution Approach 1:
By implementing dynamic NA adjustment that adapts to each illumination setting, the system optimizes energy distribution to prevent excessive concentration on any single optical element. This allows fixed high radiant power to be used for maximum throughput while the adaptive NA control prevents cumulative damage, thereby extending optical element lifetime.
Solution Approach 2:
The system changes the numerical aperture parameter based on illumination settings to optimize energy distribution. This parameter adaptation allows the system to maintain high radiant power for maximum throughput while distributing energy in a way that prevents cumulative damage to optical elements, thus extending their operational lifetime.
Data Source
AI summary
A projection exposure system and a method for operating a projection exposure system for microlithography with an illumination system are disclosed. The illumination system includes at least one variably adjustable pupil-defining element. The illumination stress of at least one optical element of the projection exposure system is determined automatically in the case of an adjustment of the at least one variably adjustable pupil-defining element. From the automatically determined illumination stress, the maximum radiant power of the light source is set or determined and/or in which an illumination system is provided with which different illumination settings can be made. Usage of the projection exposure system is recorded and, from the history of the usage, at least one state parameter of at least one optical element of the projection exposure system is determined.