Magnetized EUV Mirror Polarization Control
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Solution Overview
Problem
Existing mirror systems in EUV projection lithography do not effectively optimize the illumination and imaging properties of light, particularly in terms of polarization, leading to inefficiencies and losses when using traditional EUV polarizers.
Innovation Solution
A mirror system with a reflective surface that forms a magnetic field, allowing for the influence of polarization properties through magnetization, which can be predefined and switched using a magnetization predefining device, enabling the rotation of polarization direction and conversion between linear, elliptical, and circular polarization states with reduced losses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If traditional EUV polarizers operated in transmission are used, then polarization properties can be achieved, but energy losses are high
Solution Approach 1:
The patent inverts the conventional transmission-based polarization approach by using reflection-based polarization control through mirrors with magnetized reflective surfaces. This inversion allows polarization to be achieved with lower energy losses since reflection in the EUV range is more efficient than transmission through polarizing filters.
Solution Approach 2:
The patent changes the physical parameter of the reflective surface by introducing magnetization, which enables control over polarization properties through the magneto-optical Kerr effect. By adjusting the magnetization state of the mirror surface, different polarization states can be achieved with minimal energy loss.
2Reliability
If polarization properties are not controlled, then system complexity is reduced, but illumination and imaging properties are not optimized
Solution Approach 1:
The patent makes the mirror serve multiple functions: it simultaneously performs beam steering/reflection and polarization control. By incorporating magnetized reflective surfaces into existing mirror components, the system gains polarization control capability without adding separate polarizing elements, thus maintaining simplicity while improving reliability.
Solution Approach 2:
The mirror's reflective surface inherently provides polarization control through its magnetization, eliminating the need for additional dedicated polarization control devices. The mirror serves itself to control polarization properties while performing its primary function of guiding illumination and imaging light.
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 solution allows for optimized illumination and imaging properties by influencing polarization states with lower losses compared to traditional EUV polarizers, enabling precise control over light polarization for improved performance in EUV projection lithography.
Implementation Method 1
The polarization property of the illumination and/or imaging light can be influenced via the mirror's reflective surface forming the magnetic field, in particular by the magneto-optical Kerr effect
Data Source
AI summary
A mirror serves for use for guiding illumination and imaging light in EUV projection lithography. The mirror has a reflective surface, the reflective surface forming a magnetic field in such a way that at least one polarization property of the illumination and imaging light is influenced via the magnetic field upon reflection. A mirror system has, besides the mirror, additionally a magnetization predefining device for predefining a magnetization of the reflective surface of the mirror. An illumination optical unit has at least one mirror of this type or at least one facet mirror device comprising at least one individual mirror constructed in this way. In the case of a mirror of this type, the illumination and/or imaging properties of illumination and/or imaging light guided via the mirror are improved.