Polarization Control in Microlithography
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Solution Overview
Problem
Existing microlithographic projection exposure apparatuses face challenges in accurately setting polarization distributions due to imprecise positioning of polarization-influencing components, leading to imaging errors and loss of contrast.
Innovation Solution
A method that adjusts the optical system by establishing a distribution of IPS values in the pupil plane using a polarization-measuring instrument, allowing for precise positioning of polarization-influencing components relative to a mirror arrangement, thereby ensuring accurate polarization distribution settings.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If polarization-influencing components are used to set polarization distributions, then polarization control capability is improved, but positioning precision deteriorates leading to imaging errors
Solution Approach 1:
The patent applies preliminary action by performing an adjustment procedure before actual use. The method involves measuring the actual polarization distribution with a polarization-measuring instrument and calculating required position corrections for polarization-influencing components (such as half-wave plates or quarter-wave plates) before proceeding with precise positioning. This preliminary measurement and calculation step ensures that subsequent positioning achieves the desired polarization distribution without imaging errors.
Solution Approach 2:
The patent implements feedback by using a polarization-measuring instrument to continuously monitor the actual polarization distribution in the pupil plane. The measured data is fed back to a control system that calculates the deviation from the target polarization distribution and determines necessary position adjustments for the polarization-influencing components. This closed-loop feedback mechanism enables precise positioning and maintains accurate polarization control during operation.
2Adaptability or versatility
If mirror arrangements with independently adjustable elements are used, then polarization distribution flexibility is improved, but system complexity increases
Solution Approach 1:
The patent applies universality by designing a integrated adjustment system that can handle multiple polarization distribution configurations through a unified approach. The system uses a combination of mirror arrangements with independently adjustable elements and polarization-influencing components that can be positioned and oriented to achieve various polarization states. The control system provides a universal interface for setting different polarization distributions, reducing the operational complexity despite the multi-functional capability.
3Manufacturing precision
If precise positioning of polarization-influencing components is achieved, then imaging quality is improved, but adjustment time increases
Solution Approach 1:
The patent reduces adjustment time by performing preliminary measurements and calculations. The system captures the actual polarization distribution once, calculates the required position corrections for all polarization-influencing components, and then executes the positioning in a coordinated manner. This preliminary action eliminates the need for iterative trial-and-error adjustments, achieving precise imaging quality faster.
Solution Approach 2:
The patent replaces manual mechanical adjustment with automated control. The control system automatically calculates position corrections based on polarization measurements and actuates the polarization-influencing components (such as piezoelectric actuators or motorized stages) to the correct positions. This substitution of mechanical manual adjustment with automated electromechanical control significantly reduces adjustment time while maintaining precise positioning.
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
This method enhances the accuracy of polarization distribution settings, reducing imaging errors and maintaining contrast, allowing for flexible and precise control of polarization states in microlithographic projection exposure apparatuses.
Implementation Method 1
establishing, for a given actual position of the polarization-influencing component, a distribution of IPS values in a pupil plane of the projection exposure apparatus, wherein each IPS value denotes the degree of realization of a predetermined polarization state for a light ray reflected at a respective mirror element of the mirror arrangement
Implementation Method 2
changing the position of the polarization-influencing component on the basis of the distribution established in step a)
Implementation Method 3
a mirror arrangement with a plurality of mirror elements, which can be adjusted independently from one another for changing an angular distribution of the light reflected by the mirror arrangement
Data Source
AI summary
A method for adjusting an optical system in a microlithographic projection exposure apparatus includes establishing, for a given actual position of a polarization-influencing component, a distribution of IPS values in a pupil plane of the projection exposure apparatus. Each IPS value denotes the degree of realization of a predetermined polarization state for a light ray reflected at a respective mirror element of the mirror arrangement. The method also includes changing the position of the polarization-influencing component on the basis of the established distribution.