Reflective Mask Multi-Layer Structure Equalizing Exposure Doses
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Solution Overview
Problem
Existing reflective masks with phase shift functions face challenges in simultaneously achieving appropriate exposure doses for both fine patterns and peripheral patterns, leading to potential insufficient exposure for peripheral regions, which can decrease throughput in exposure processing.
Innovation Solution
A reflective mask is designed with a multi-layer reflection layer configuration that includes a device region and a peripheral region, where the peripheral region is covered with an absorber film, allowing for equal exposure doses between the two regions through the use of alternating multi-layer film structures with different numbers of layers, enabling batch exposure while maintaining phase shift performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a reflective mask with phase shift function is used to form fine patterns, then the pattern resolution is improved, but the peripheral regions receive insufficient exposure dose requiring additional exposure processes
Solution Approach 1:
The patent applies local quality by differentiating the treatment of device regions and peripheral regions. The absorber film is selectively removed only from peripheral regions while maintaining the multi-layer film structure, creating locally optimized exposure characteristics for each region type.
Solution Approach 2:
The mask surface is segmented into device regions and peripheral regions with distinct structural characteristics. This segmentation allows independent optimization of exposure doses for fine patterns in device regions and sufficient exposure in peripheral regions simultaneously.
2Manufacturing precision
If the absorber film is removed from peripheral regions to increase exposure dose, then the exposure uniformity is improved, but the mask structure complexity increases
Solution Approach 1:
The absorber film removal is applied locally only to peripheral regions rather than uniformly across the entire mask. This localized modification achieves exposure uniformity improvement while minimizing the increase in overall mask structure complexity.
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 configuration allows for simultaneous exposure of fine and peripheral patterns with approximately equal exposure doses, improving throughput and enhancing aerial image contrast, thereby addressing the inefficiencies in existing reflective mask technologies.
Implementation Method 1
a first region having a plurality of first patterns, a second region surrounding the first region, and a third region within the second region. The reflection layer includes a stack of alternating first layers and second layers... allowing for equal exposure doses between the two regions through the use of alternating multi-layer film structures with different numbers of layers, enabling batch exposure while maintaining phase shift performance
Data Source
AI summary
According to one embodiment, a reflective mask comprises a reflection layer including a first region having a plurality of first patterns, a second region surrounding the first region, and a third region within the second region. The reflection layer includes a stack of alternating first layers and second layers. An absorber film covers the second region and has a second pattern that includes an opening exposing a portion of the third region. In some examples, the third region can include a plurality of third patterns therein.