EUV Optical System Polarization Control via Rotatable Brewster Angle Reflection
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Solution Overview
Problem
EUV microlithographic projection exposure systems face increasing transmission loss due to reflections required for optimizing polarization distributions, impairing their performance.
Innovation Solution
An optical system using a polarization-influencing arrangement with two reflection surfaces arranged at specific angles, operating at the Brewster angle to convert unpolarized EUV light into linearly polarized light, allowing flexible polarization distribution settings with reduced transmission loss through rotation and minimal reflections.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If multiple reflection surfaces are used to optimize polarization distribution, then imaging contrast is improved, but transmission loss increases
Solution Approach 1:
The patent changes the geometric parameters of the reflection surfaces, specifically arranging them at angles of 0°±10° or 90°±10° relative to each other, and setting the angle of incidence at 45°±5° to optimize polarization conversion while minimizing transmission loss
Solution Approach 2:
The polarization-influencing arrangement is made rotatable about an axis parallel to the light propagation direction, enabling dynamic adjustment of polarization distribution during operation without requiring additional reflection surfaces
2Productivity
If polarization distribution is changed during operation, then imaging performance is optimized, but device complexity increases
Solution Approach 1:
The patent implements a rotatable polarization-influencing arrangement that can dynamically change polarization distribution during operation by rotating about an axis parallel to the light propagation direction, providing flexibility without complex multi-component systems
Solution Approach 2:
The single rotatable polarization-influencing arrangement serves multiple functions: it can generate linear polarization from unpolarized light, adjust polarization distribution dynamically, and optimize imaging contrast, replacing what would otherwise require multiple separate optical components
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 approach effectively generates linearly polarized light with increased reflectivity and reduced loss, enabling flexible polarization and intensity distribution settings in the pupil plane with minimal structural complexity and transmission loss.
Implementation Method 1
light incident on the first reflection surface during the operation of the optical system forms an angle of 45°±5° with said first reflection surface
Implementation Method 2
at least one polarization-influencing arrangement having a first reflection surface and a second reflection surface
Implementation Method 3
the light passing from the first reflection surface to the second reflection surface in the arrangement according to the invention is already almost completely s-polarized, as a result of which the reflectivity at the second reflection surface increases
Data Source
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AI summary
The invention relates to an optical system of a microlithographic projection exposure apparatus, in particular for operation in the EUV, comprising at least one polarization-influencing arrangement (100, 200,...) having a first reflection surface (110, 210,...) and a second reflection surface (120, 220,...), wherein the first reflection surface (110, 210,...) and the second reflection surface (120, 220,...) are arranged at an angle of 0°±10° or at an angle of 90°±10° relative to one another, wherein light incident on the first reflection surface (110, 210,...) during the operation of the optical system forms an angle of 45°±5° with said first reflection surface, and wherein the polarization-influencing arrangement (100, 200,...) is rotatable about a rotation axis (A) running parallel to the light propagation direction of light incident on the first reflection surface (110, 210,...) during the operation of the optical system.