Magnetostrictive EUV Optical Element for Wavefront Correction
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Solution Overview
Problem
Reflective optical elements in EUV lithography systems face challenges in maintaining optimal optical properties due to manufacturing fluctuations and operational variations, requiring dynamic correction of wavefront aberrations without the need for external field-generating devices.
Innovation Solution
Incorporating a permanent-magnetic material layer that generates a static magnetic field to locally deform the active layer, allowing for static correction of wavefront aberrations within the optical element, potentially eliminating the need for external field-generating devices like coils or electromagnets.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If external field-generating devices (coils or electromagnets) are used to correct wavefront aberrations, then optical properties can be dynamically adjusted, but device complexity and construction difficulty increase
Solution Approach 1:
The optical element incorporates a magnetizable layer that generates its own magnetic field through magnetization, eliminating the need for external field-generating devices. The layer serves itself by creating the magnetic field required for magnetostrictive deformation of the active layer,从而实现波前像差的校正
Solution Approach 2:
The magnetizable layer is integrated directly into the optical element structure, merging the field-generating function with the optical correction function. This combination allows the optical element to both reflect EUV radiation and generate the magnetic field needed for active layer deformation, simplifying the overall system construction
2Reliability
If the magnetizable layer is fully magnetized, then wavefront correction capability is maximized, but manufacturing precision requirements increase
Solution Approach 1:
The patent applies local quality by magnetizing only specific regions of the magnetizable layer rather than the entire layer uniformly. This allows selective correction of local wavefront aberrations while reducing the overall manufacturing precision requirements for magnetization control
Solution Approach 2:
The invention utilizes parameter changes by varying the degree and distribution of magnetization in the magnetizable layer. By controlling magnetic field strength and distribution, the system can achieve different levels and patterns of active layer deformation to correct various types of wavefront aberrations
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 enables precise correction of wavefront aberrations and simplifies the construction of optical arrangements by using a self-generated magnetic field to adjust the optical element's surface shape and wavefront, improving imaging quality and reducing manufacturing defects.
Implementation Method 1
by means of an external magnetic field, the Weiss domains are altered in terms of the relative size with respect to one another or (at very high field strengths) the orientation of the magnetization is rotated and a change in the shape of the material is thus obtained
Data Source
Figure 1
Figure 2a~2c
Figure 3a~3d
AI summary
The invention relates to an optical element (21) comprising a substrate (30) and a reflective coating (31). The reflective coating (31) has, in particular for the reflection of EUV radiation, a plurality of layer pairs having alternate layers (33a, 33b) composed of a high refractive index material and a low refractive index material, wherein at least one active layer (34) composed of a magnetostrictive material is formed within the reflective coating (31). The invention also relates to an optical element (21) having a substrate (30) and a reflective coating (31), wherein the optical element (21 ) comprises at least one first active layer comprising a material having positive magnetostriction and at least one second active layer comprising a material having negative magnetostriction, wherein the layer thicknesses and the layer materials of the active layers are chosen such that mechanical stress changes or changes in length of the active layers that are produced by a magnetic field mutually compensate for one another. The invention also relates to an optical arrangement, in particular an EUV lithography apparatus, which comprises at least one such optical element (21).