Adhesion Layer for EUV Photoresist Underlayer Stability
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Solution Overview
Problem
The challenge in forming features with smaller dimensions on substrates for electronic devices is exacerbated by pattern collapse due to differences in surface polarity between photoresist underlayers and EUV photoresist layers, particularly with spin-on glass and plasma-deposited oxides, which lack desired etch selectivity and pattern stability.
Innovation Solution
A method involving a cyclical process, such as atomic layer deposition, to form a thin, uniform photoresist underlayer with an adhesion layer, using silicon and metal precursors to achieve desired surface energy and adhesion, and a plasma-enhanced process to deposit layers with precise thickness and low surface roughness, ensuring compatibility with EUV lithography.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If spin-on glass or plasma-deposited oxides are used as photoresist underlayers, then the underlayer can be formed, but pattern collapse occurs due to higher surface polarity compared to EUV photoresist
Solution Approach 1:
The patent introduces an adhesion layer as an intermediary between the photoresist underlayer and the EUV photoresist layer. This adhesion layer has lower surface polarity than traditional underlayers, creating a gradient that reduces the polarity mismatch and prevents pattern collapse while maintaining structural integrity.
Solution Approach 2:
The patent modifies the surface polarity parameter of the underlayer system by depositing a specific adhesion layer with controlled composition and thickness. This changes the effective surface energy characteristics to be more compatible with EUV photoresist, thereby improving pattern stability.
2Reliability
If plasma-deposited oxides are used as photoresist underlayers, then deposition can be achieved, but etch selectivity is insufficient
Solution Approach 1:
The patent creates a composite structure consisting of the original photoresist underlayer combined with a specially designed adhesion layer. This composite structure provides both the mechanical support of the underlayer and the enhanced etch selectivity of the adhesion layer, achieving superior overall performance.
3Productivity
If feature dimensions are reduced for higher device density, then device capacity increases, but pattern collapse becomes more severe
Solution Approach 1:
The adhesion layer serves as a mediator that provides mechanical support and reduces surface energy differences, enabling the formation of finer patterns without collapse. This intermediary layer allows feature dimensions to be reduced while maintaining pattern integrity.
4Area of stationary object
If a thicker photoresist underlayer is used, then coverage is improved, but adhesion to the photoresist layer deteriorates
Solution Approach 1:
The patent applies different material properties to different layers: the photoresist underlayer provides coverage and mechanical support, while the adhesion layer provides surface energy compatibility and bonding. This local specialization of functions allows each layer to optimize its role without compromising the other.
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 results in structures with improved etch selectivity, pattern quality, and stability, maintaining high fidelity and reducing defects, while being compatible with EUV sensitivity and integration, with the adhesion layer enhancing the adhesion between the underlayer and the EUV photoresist layer.
Implementation Method 1
forming a plasma using the inert gas to form activated species that react with the silicon precursor or a derivative thereof to form the adhesion layer
Implementation Method 2
The adhesion layer can be formed using a first cyclic deposition process that includes providing a silicon precursor to the reaction chamber, providing an inert gas into the reaction chamber, and forming a plasma using the inert gas
Data Source
AI summary
Methods of forming structures including a photoresist underlayer and an adhesion layer and structures including the photoresist underlayer and adhesion layer are disclosed. Exemplary methods include forming the photoresist underlayer and forming an adhesion layer using a cyclical deposition process. The adhesion layer can be formed within the same reaction chamber used to form the photoresist underlayer.