EUV Lithography Assist Layer for Pattern Collapse and LWR
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Solution Overview
Problem
Current EUV lithography methods face challenges in achieving simultaneous improvement in line width roughness (LWR) and sensitivity, with existing resists often compromising between the two, and requiring high energy doses and long exposure times due to limited radiation sources.
Innovation Solution
A method involving a substrate with an assist layer formed from a polymeric metal alkoxide composition, which is cured and applied with a photoresist layer, subjected to EUV radiation with controlled doses, allowing for pattern formation without the need for photoacid generators or halogens in the resist, and utilizing the assist layer for secondary electron generation to enhance acid-generation efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If halogens are added to increase resist absorbance, then sensitivity and LWR are improved, but tapering occurs at the bottom of the resist
Solution Approach 1:
The patent introduces an assist layer as an intermediary component between the substrate and the photoresist layer. This assist layer contains the halogenated compounds that generate secondary electrons upon EUV irradiation, thereby improving resist sensitivity and LWR without requiring the photoresist itself to contain halogens. This mediator approach allows the photoresist to maintain uniform absorbance and avoid tapering while still achieving the desired secondary electron generation effects.
Solution Approach 2:
The patent segments the functional components by separating the halogenated assist layer from the photoresist layer. The assist layer is applied first and cured to form a distinct functional layer, followed by the application of the photoresist layer. This segmentation allows each layer to be optimized independently - the assist layer for secondary electron generation and the photoresist for pattern formation - thereby resolving the contradiction between improving LWR/sensitivity and avoiding tapering.
2Manufacturing precision
If EUV exposure time is increased to improve pattern quality, then LWR is improved, but throughput decreases
Solution Approach 1:
The assist layer acts as a mediator that enhances the efficiency of EUV energy utilization. By generating secondary electrons that directly contribute to acid formation in the photoresist, the assist layer amplifies the effective dose delivered to the resist. This allows for reduced exposure times to achieve the same pattern quality, thereby improving throughput while maintaining LWR performance.
Solution Approach 2:
The patent changes the physical-chemical parameters of the system by introducing materials with high secondary electron generation cross-sections in the assist layer. This parameter change increases the efficiency of energy conversion from EUV photons to acid-forming events, effectively reducing the required exposure dose and exposure time while maintaining or improving pattern quality.
3Manufacturing precision
If thinner films are used to achieve smaller features, then critical dimension targets are met, but pattern collapse occurs
Solution Approach 1:
The patent applies local quality by creating a functional gradient through the assist layer. The assist layer provides localized secondary electron generation precisely where needed - at the interface and within the lower portions of the photoresist structure. This localized enhancement of acid formation efficiency allows for better control of pattern formation in thin films, reducing the tendency for pattern collapse while achieving the required critical dimensions.
Solution Approach 2:
The patent employs composite material structures by combining the assist layer (containing halogenated compounds or high-Z elements) with the photoresist layer. This composite structure leverages the complementary properties of each material - the assist layer for secondary electron generation and the photoresist for pattern definition - enabling the formation of stable, high-resolution patterns in thin film configurations that would otherwise be prone to collapse.
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 improves LWR and sensitivity while reducing the EUV energy dose required, enabling high-resolution pattern formation with resolutions below 32 nm and efficient pattern transfer to the substrate.
Implementation Method 1
utilizing the assist layer for secondary electron generation to enhance acid-generation efficiency
Implementation Method 2
forming an assist layer on said substrate, or on said one or more intermediate layers, if present, said assist layer being formed from a composition comprising a polymeric metal alkoxide... and being a cured film
Data Source
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AI summary
The present invention provides novel methods of fabricating microelectronics structures, and the resulting structures formed thereby, using EUV lithographic processes. The method involves utilizing an assist layer immediately below the photoresist layer. The assist layer can either be directly applied to the substrate, or it can be applied to any intermediate layer(s) that may be applied to the substrate. The preferred assist layers are formed from spin-coatable, polymeric compositions. The inventive method allows reduced critical dimensions to be achieved with improved dose-to-size ratios, while improving adhesion and reducing or eliminating pattern collapse issues.