Tile Wave Plate Assembly for Lithography Polarization Control
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Solution Overview
Problem
Conventional polarizing filters in lithography uniformly polarize light, reducing transmissivity by at least 50% and failing to provide custom polarization patterns, while mosaic tiles made of birefringent materials are vulnerable to thermal expansion and have poor angular acceptance, leading to intensity variations and reduced imaging quality.
Innovation Solution
A tile wave plate assembly with mechanically separated layers of mosaic tiles, forming a pseudo or true zero order wave plate, which non-subtractively rotates the polarization of the light beam, providing controlled gap spacing and customizable polarization patterns.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If conventional polarizing filters are used to polarize light uniformly, then polarization control is achieved, but transmissivity is reduced by at least 50%
Solution Approach 1:
The wave plate is divided into multiple mosaic tiles arranged in a specific pattern, where each tile contributes to the overall polarization control. This segmentation allows different regions of the beam to have customized polarization patterns while maintaining high transmissivity through non-subtractive polarization rotation.
Solution Approach 2:
Different regions of the wave plate have different polarization characteristics. The mosaic tile arrangement creates local variations in polarization rotation, enabling custom polarization patterns for different parts of the beam without uniformly affecting the entire beam like conventional polarizing filters.
2Illumination intensity
If mosaic tiles made of birefringent materials are used, then polarization rotation is achieved, but thermal expansion causes intensity variations
Solution Approach 1:
The wave plate assembly combines multiple materials with different thermal expansion characteristics. By layering tiles with varying birefringent properties and supporting them on substrates with appropriate thermal coefficients, the design compensates for thermal expansion effects and maintains intensity uniformity across the beam.
Solution Approach 2:
The design carefully selects and adjusts the optical and thermal parameters of the mosaic tiles and substrates. By optimizing the thickness, material composition, and arrangement of tiles, the system achieves both polarization rotation and thermal stability, preventing intensity variations caused by thermal expansion.
3Adaptability or versatility
If mosaic tiles are used for polarization control, then custom polarization patterns are provided, but angular acceptance is poor
Solution Approach 1:
The wave plate design operates primarily in the polarization dimension while maintaining good angular acceptance. By arranging mosaic tiles to rotate polarization rather than block light, the system achieves custom polarization patterns without the poor angular acceptance that plagues conventional birefringent tile designs.
4Stability of the object's composition
If layers are mechanically separated to form controlled gap spacing, then thermal expansion is managed, but device complexity increases
Solution Approach 1:
The wave plate is segmented into multiple layers of mosaic tiles with controlled gap spacing between them. This segmentation allows each layer to expand independently at different rates, managing thermal expansion effects while the overall structure remains modular and manageable.
Solution Approach 2:
The gap spacing between layers acts as an intermediary that accommodates thermal expansion differences. These controlled gaps allow for thermal movement without compromising the optical alignment or causing intensity variations, effectively mediating between thermal stability and structural integrity.
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
The solution enhances contrast and imaging quality by reducing reflections and scattered light, maintaining uniformity and efficiency in light coupling, and is thermally stable, suitable for high numerical aperture systems in lithography.
Implementation Method 1
mosaic tiles made of birefringent material (such as naturally birefringent crystals)
Implementation Method 2
light losses because of reflection at the outer resist boundary layer
Data Source
AI summary
The present invention relates to an apparatus for polarizing an incident light beam. In embodiments, a tile wave plate assembly is provided. The tile wave plate includes a layered structure having a substrate plate and two layers of mosaic tiles. The layers of the apparatus are mechanically separated to form a controlled gap spacing. The mosaic tiles can be configured to form a pseudo or true zero order wave plate.