EUV Lithography Multi-Layer Stack for Line Edge Roughness
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Solution Overview
Problem
Current EUV lithography methods result in poor edge roughness and weak patterns, rendering substrates useless due to high photon shot noise and stochastic effects, which are not effectively addressed by conventional photolithography techniques.
Innovation Solution
A multi-layer stack for extreme ultraviolet lithography is introduced, comprising an atomically smooth layer with low roughness and one or more underlayers with high etch contrast, deposited using plasma-enhanced chemical vapor deposition (PECVD), which includes amorphous carbon and silicon layers, to improve pattern smoothness and etch contrast, and a thin photoresist layer to reduce exposure dose and enhance throughput.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional photolithography methods are used for EUV lithography, then the process is simpler, but the line edge roughness is poor and patterns are weak
Solution Approach 1:
The patent divides the lithography structure into multiple functional layers: photoresist layer, atomically smooth layer, underlayer, and target layer. Each layer serves a specific purpose in reducing roughness and improving pattern quality, directly addressing the line edge roughness problem through structural segmentation
Solution Approach 2:
The atomically smooth layer acts as an intermediary between the photoresist and the underlayer, providing a ultra-smooth interface that reduces line edge roughness. This intermediate layer mediates the interaction between photoresist patterns and the underlying structure, improving pattern fidelity
2Productivity
If a thick photoresist layer is used, then the pattern strength is improved, but the exposure dose increases and throughput decreases
Solution Approach 1:
The patent changes the physical and chemical parameters of the photoresist layer by depositing it on an atomically smooth surface, which improves pattern formation efficiency. This allows using thinner photoresist layers (reducing exposure dose and increasing throughput) while maintaining or improving pattern quality through the enhanced interface characteristics
3Manufacturing precision
If the atomically smooth layer is made thicker, then the roughness reduction is improved, but the etch contrast to adjacent layers is reduced
Solution Approach 1:
The patent optimizes the thickness parameter of the atomically smooth layer to a specific range that balances two competing requirements: thick enough to provide sufficient surface smoothing effect, but thin enough to maintain adequate etch contrast with adjacent layers for reliable pattern transfer
Solution Approach 2:
The atomically smooth layer provides localized quality improvement at the photoresist-interface, creating a ultra-smooth region specifically where needed for pattern definition, while maintaining different properties in adjacent regions for etching functionality
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 multi-layer stack achieves optimized low line edge roughness, improved throughput, and low local critical dimension uniformity, effectively reducing errors and enhancing the accuracy of optical leveling sensors in EUV lithography, enabling the production of smaller features with reduced roughness and increased manufacturing efficiency.
Implementation Method 1
each layer is deposited by plasma-enhanced chemical vapor deposition
Implementation Method 2
an atomically smooth layer with an average local roughness of less than a monolayer
Data Source
AI summary
Provided herein are multi-layer stacks for use in extreme ultraviolet lithography tailored to achieve optimum etch contrast to shrink features and smooth the edges of features while enabling use of an optical leveling sensor with little or reduced error. The multi-layer stacks may include an atomically smooth layer with an average local roughness of less than a monolayer, and one or more underlayers, which may be between a target layer to be patterned and a photoresist. Also provided are methods of depositing multi-layer stacks for use in extreme ultraviolet lithography.