Optical Manipulator Wavefront Error Compensation in Microlithography
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Solution Overview
Problem
Microlithography projection exposure systems face challenges in dynamically correcting imaging errors that occur or change during operation due to factors like lens heating, which leads to wavefront aberrations, and existing control methods are inadequate in handling travel restrictions and faulty zones, resulting in suboptimal wavefront error compensation.
Innovation Solution
A method and system that determine wavefront errors and generate travel vectors using optimization algorithms, with a correction mechanism to adjust optical power across zones, accounting for restriction parameters and using pre-calculated correction value vectors to compensate for travel limitations, allowing continued operation even with faulty zones.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the power of electromagnetic radiation is increased to meet miniaturization demands, then imaging resolution is improved, but lens heating increases causing wavefront aberrations
Solution Approach 1:
The patent converts the harmful lens heating effect into a beneficial one by using the same heating mechanism to compensate for wavefront aberrations. Optical manipulators with multiple zones apply localized heating to correct imaging errors caused by lens heating, thus transforming the harmful thermal effect into a corrective tool that maintains imaging resolution.
2Manufacturing precision
If optical manipulators with multiple zones are used to correct wavefront errors, then imaging performance is improved, but device complexity increases
Solution Approach 1:
The patent divides the optical manipulator into multiple independently controllable zones, each capable of applying localized optical effects. This segmentation allows precise wavefront error compensation by adjusting individual zones, maintaining high imaging performance while managing complexity through modular control.
Solution Approach 2:
The patent changes the optical parameters of different manipulator zones dynamically to correct wavefront errors. By adjusting parameters such as refractive index or surface shape in specific zones, the system achieves effective wavefront compensation without requiring complete redesign of the entire manipulator structure.
3Reliability
If travel restrictions in faulty zones are enforced, then system reliability is improved, but wavefront error compensation capability deteriorates
Solution Approach 1:
The patent discards the functionality of faulty zones by enforcing travel restrictions on them, preventing unreliable operation. Simultaneously, it recovers compensation capability by redistributing the corrective function to other healthy zones, which increase their adjustment range to compensate for the restricted faulty zones, thus maintaining overall wavefront error compensation.
Solution Approach 2:
The patent dynamically adjusts the travel limits of different manipulator zones based on their operational status. Healthy zones can operate with full or extended ranges, while faulty zones have restricted travel. This dynamic allocation of adjustment ranges ensures reliable operation of the entire manipulator system while maintaining wavefront compensation capability through coordinated control of functional zones.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Enables effective real-time compensation of wavefront errors by adjusting optical power across zones, ensuring optimal imaging performance despite travel restrictions and faulty zones, thereby extending the lifespan and efficiency of microlithography projection exposure systems.
Implementation Method 1
Due to the absorption of the infrared radiation, the irradiated lens sections are correspondingly heated
Implementation Method 2
The power absorbed in this way leads to inhomogeneous heating of the optical elements, which causes changes in the refractive index, expansion and mechanical stresses
Implementation Method 3
A further cause of operational imaging errors is the unavoidable absorption of part of the electromagnetic radiation used for exposure in the optical elements of the projection lens. The power absorbed in this way leads to inhomogeneous heating of the optical elements
Data Source
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AI summary
The invention relates to a method for controlling a projection exposure system (10) for microlithography with a projection lens (22) and an optical manipulator (136, 236, 336) which has a plurality of zones (146, 246, 346) with individually adjustable optical effect, and comprises the steps: determining a wavefront error of the projection exposure system (10), generating a position vector suitable for correcting the wavefront error with positions for each zone (146, 246, 346) of the optical manipulator (136, 236, 336), determining a limiting parameter with respect to the position for at least one zone (146, 246, 346) of the optical manipulator, and checking the position of the generated position vector for feasibility.In the event of limitations in feasibility, a correction value vector is obtained with correction values for several of the zones (146, 246, 346) of the optical manipulator, a corrected displacement vector is determined by adding the correction values of the correction value vector to the corresponding displacements of the generated displacement vector, and the optical effect of all zones (146, 246, 346) of the optical manipulator is adjusted using the corrected displacement vector to compensate for the wavefront error.