EUV Reticle Black Border Absorber Structure for Edge Defect Control
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Solution Overview
Problem
In extreme ultraviolet (EUV) exposure processes, the black border area of reticles affects the imaging of semiconductor chip edges due to unblocked EUV light, leading to defects in photoresist patterns.
Innovation Solution
A reticle design featuring a multi-layer structure for reflecting EUV light on the image and black border areas, with a capping layer, first absorber layer patterns, and an absorber layer structure including a hard mask pattern and second absorber layer, ensuring complete absorption of EUV light in the black border area to prevent edge region defects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a simple absorber layer is used in the black border area, then the device complexity is reduced, but the optical density is insufficient and EUV light leaks causing photoresist defects
Solution Approach 1:
The absorber layer structure uses a composite of multiple absorber layer patterns (first, second, and third) with different materials and optical densities stacked in sequence. This composite structure achieves high optical density (OD>3.0) by combining the light-absorbing properties of different materials rather than relying on a single thick layer, thereby preventing EUV light leakage while maintaining manufacturing feasibility.
Solution Approach 2:
The solution transitions from a single-layer absorber design to a multi-layer stacked structure in the vertical dimension. By stacking multiple absorber layer patterns with alternating materials and optical densities, the structure achieves superior light blocking performance through cumulative absorption across multiple interfaces and layers, effectively eliminating EUV light leakage that cannot be achieved with a single layer.
2Reliability
If a multi-layer absorber structure is used in the black border area, then the optical density increases to block EUV light, but the manufacturing complexity increases
Solution Approach 1:
The absorber layer structure segments the black border area into multiple functional zones with different absorber layer configurations. The first absorber layer pattern covers the entire black border area, the second pattern covers specific regions, and the third pattern fills remaining areas. This segmentation allows optimized light blocking in different zones while simplifying the overall manufacturing process by using sequential deposition steps.
Solution Approach 2:
The invention varies the optical density parameters of different absorber layer patterns to achieve cumulative light blocking. The first absorber layer has optical density of 1.5-2.5, the second has 2.0-3.0, and the third has 1.0-2.0. By controlling and varying these parameters across layers, the structure achieves total optical density >3.0 while maintaining manufacturability through parameter optimization rather than excessive thickness.
3Reliability
If the absorber layer structure covers the entire upper surface of the capping layer in the black border area, then edge region defects are prevented, but the material consumption increases
Solution Approach 1:
The absorber layer structure applies different absorber layer patterns to different local regions of the black border area based on their specific requirements. The first absorber layer pattern covers the entire area, the second pattern is applied to regions requiring enhanced blocking, and the third pattern fills specific zones. This local quality approach ensures optimal light blocking where needed while reducing material consumption in areas with lower requirements.
Solution Approach 2:
The invention uses partial coverage strategies where the second and third absorber layer patterns are applied only to specific regions rather than the entire black border area. This partial action approach provides sufficient light blocking for critical regions while avoiding excessive material deposition in non-critical areas, thereby reducing overall material consumption while maintaining photoresist pattern quality.
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 effectively absorbs EUV light in the black border area, preventing light from reaching the target substrate and reducing defects in photoresist patterns at semiconductor chip edges during exposure.
Implementation Method 1
The multi-layer structure for reflecting EUV light may be formed on the image area and the black border area of the substrate
Implementation Method 2
The absorber layer structure may include the first absorber layer pattern, a hard mask pattern, and a second absorber layer pattern sequentially stacked. The absorber layer structure may cover an entire upper surface of the capping layer in the black border area
Data Source
AI summary
A reticle in an apparatus for extreme ultraviolet (EUV) exposure includes a substrate having an image area and a black border area surrounding the image area, a multi-layer structure on the image area and the black border area of the substrate, the multi-layer structure to reflect EUV light, a capping layer covering the multi-layer structure, first absorber layer patterns on the capping layer in the image area and the black border area, and an absorber structure on the capping layer in the black border area, the absorber structure including one of the first absorber layer patterns, a hard mask pattern, and a second absorber layer pattern sequentially stacked, the absorber structure covering an entire upper surface of the capping layer in the black border area.