EUV Mask Line Patterns with Local Width Compensation
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Solution Overview
Problem
Defects on EUV masks used in lithography processes can lead to defects in the devices manufactured, due to foreign materials adhering to the substrate and causing phase defects, resulting in non-uniform optical properties and reduced EUV reflectivity.
Innovation Solution
The EUV mask design features line patterns with alternating first and second layers, where the width of the first portion including a defect is locally enlarged to compensate for the defect, increasing the reflection area and maintaining uniformity, thereby reducing the impact of foreign materials on EUV reflectivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If foreign materials adhere to the substrate, then phase defects are formed and optical properties become non-uniform, but EUV reflectivity is reduced
Solution Approach 1:
The patent applies local quality by creating a modifying pattern with different properties (varying line widths) at specific locations where defects are detected. The line width in the modifying pattern is adjusted locally to compensate for the optical property changes caused by foreign materials, thereby maintaining uniform EUV reflectivity across the mask surface.
Solution Approach 2:
The patent changes the geometric parameter (line width) of the pattern lines in the modifying pattern to compensate for defect-induced optical property changes. By adjusting the line width parameter, the optical path length and reflectivity are modified to offset the harmful effects of foreign materials adhering to the substrate.
2Ease of manufacture
If the line width is uniformly maintained, then manufacturing precision is simplified, but defect impact on EUV reflectivity increases
Solution Approach 1:
Instead of maintaining uniform line width across the entire mask, the patent introduces local variations in line width within the modifying pattern. This allows the line width to be adjusted at specific defect locations to compensate for optical property changes, while other areas maintain standard dimensions.
Solution Approach 2:
The modifying pattern is designed and positioned in advance at locations where defects are detected. By pre-planning the line width adjustments in the modifying pattern, the patent prepares compensation measures before the mask is fully manufactured, ensuring that defect impacts are addressed without requiring post-manufacturing corrections.
3Reliability
If a modifying pattern with variable line widths is introduced, then EUV reflectivity uniformity is improved, but device complexity increases
Solution Approach 1:
The patent segments the mask pattern into two distinct parts: the original pattern and the modifying pattern. The modifying pattern is further segmented into multiple line segments with different widths, each tailored to compensate for specific defect characteristics. This segmentation allows for targeted corrections without redesigning the entire mask.
Solution Approach 2:
The modifying pattern acts as an intermediary element between the original pattern and the substrate. It mediates the optical interaction by introducing controlled line width variations that compensate for defect-induced disturbances, thereby maintaining overall optical property uniformity without directly modifying the original pattern design.
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 design effectively controls the generation of defects in workpieces by offsetting the negative impact of foreign materials, ensuring consistent EUV reflectivity and reducing device defects during the lithography process.
Implementation Method 1
the plurality of first layers and the plurality of second layers alternately stacked on the substrate... different reflectivity than the line portions
Data Source
AI summary
A mask includes a plurality of line patterns provided on a substrate, the plurality of line patterns each including a line comprising a plurality of first layers and a plurality of second layers alternately stacked on the substrate. The lines of the plurality of line patterns extend in a first direction and the lines of the plurality of line patterns are spaced in a second direction crossing the first direction. A line of one of the plurality of line patterns has a first portion and a second portion on a side of the first portion in the first direction, the first portion wider than the second portion in the second direction.