Bright Field Reticle Absorption Zones for High-NA EUV Stitching
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Solution Overview
Problem
The use of bright field reticles in high-NA EUV photolithography processes faces challenges with pattern distortion and low wafer yields due to overlapping exposures in the stitching area, leading to undesired breaks in metal line patterns.
Innovation Solution
Employing two bright field reticles with additional absorption areas adjacent to the black border areas to facilitate double exposure and stitching, ensuring proper formation of high-density metal line patterns without defects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If double exposure technique is used with bright field reticles in high-NA EUV photolithography, then feature density can be increased, but pattern overlap causes distorted or damaged photoresist patterns leading to low wafer yields
Solution Approach 1:
The reticle is divided into distinct functional zones: a main pattern area for forming circuit features and an additional absorption area positioned adjacent to the black border. This segmentation allows the additional absorption area to selectively block EUV light in the stitching region, preventing pattern overlap damage while the main pattern area maintains high feature density through double exposure techniques.
Solution Approach 2:
The absorption material is strategically positioned only in specific locations (adjacent to the black border in the stitching area) rather than uniformly across the reticle. This local quality approach ensures that light blocking occurs only where pattern overlap would cause damage, while other regions maintain full transparency for optimal pattern formation and high feature density.
2Reliability
If additional absorption area is added to prevent pattern breakages, then wafer yields improve, but reticle structure complexity increases
Solution Approach 1:
The reticle is divided into distinct functional zones: a main pattern area for forming circuit features and an additional absorption area positioned adjacent to the black border. This segmentation allows the additional absorption area to selectively block EUV light in the stitching region, preventing pattern overlap damage while the main pattern area maintains high feature density through double exposure techniques.
Solution Approach 2:
The absorption material is strategically positioned only in specific locations (adjacent to the black border in the stitching area) rather than uniformly across the reticle. This local quality approach ensures that light blocking occurs only where pattern overlap would cause damage, while other regions maintain full transparency for optimal pattern formation and high feature density.
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 reliable production of high-density metal line patterns with improved wafer yields by preventing pattern distortion and breakage in the stitching area, enhancing integrated circuit feature density and performance.
Implementation Method 1
an absorption material positioned between the main pattern and the black border area
Implementation Method 2
forming reflective multilayer on a substrate
Data Source
AI summary
A first bright field reticle and a second bright field reticle are utilized for a double exposure EUV photolithography process in which exposure areas of the first and second bright field reticles overlap. The first and second reticles each include, respectively, a substrate, a reflective multilayer on the substrate, a main pattern of absorption material on the reflective multilayer, a black border area, and an additional absorption area of the absorption material between the black border and the main pattern.