EUV Lithography Membrane Composite Structure for Contamination Control
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Solution Overview
Problem
In EUV lithography, existing membrane assemblies for protecting patterning devices are prone to contamination, leading to manufacturing defects and require frequent cleaning or replacement, which disrupts the manufacturing process and increases costs due to their limited durability and high sensitivity to airborne particles.
Innovation Solution
A membrane assembly for EUV lithography with a thickness of no more than 200 nm, comprising a stack of silicon layers and silicon compound layers made with elements like boron, phosphorous, or sulphur, and capping layers such as ruthenium with anti-migration layers of molybdenum and titanium, designed to enhance emissivity and reduce the risk of contamination while maintaining mechanical stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a membrane assembly is used to protect the patterning device, then contamination is reduced, but the membrane itself becomes sensitive to airborne particles and requires frequent cleaning or replacement
Solution Approach 1:
The membrane is constructed as a composite structure with multiple functional layers: a porous substrate layer providing mechanical support, a first functional layer (e.g., fluorinated silane or polymer coating) that repels hydrophobic contaminants, and a second functional layer (e.g., charged polymer or surfactant coating) that repels charged particles. This multi-layer composite approach enables the membrane to simultaneously protect against various contamination types while maintaining durability and reducing replacement frequency.
Solution Approach 2:
The patent modifies the surface properties of the membrane by applying functional coatings that change the surface energy, charge density, and chemical composition. These parameter changes enable the membrane surface to actively repel contaminants through electrostatic and hydrophobic effects, transforming the membrane from a passive barrier to an active contamination-resistant surface.
2Volume of moving object
If the membrane thickness is reduced to minimize space, then mounting features can be smaller, but the membrane may become mechanically weaker and more prone to failure
Solution Approach 1:
The patent employs ultra-thin membrane structures (e.g., 100 nm to 2 µm thickness) that are engineered to provide adequate mechanical strength through careful material selection and support structure design. The porous substrate layer is designed with optimized pore size and wall thickness to maintain structural integrity while minimizing overall thickness, enabling space reduction without compromising mechanical reliability.
Solution Approach 2:
The membrane structure incorporates localized reinforcement through the border region and mounting feature areas, where the substrate material density and cross-linking are increased to provide enhanced mechanical strength precisely where needed, while the central filtering area remains thin for optimal filtration performance and minimal space occupation.
3Ease of manufacture
If conventional membrane materials are used, then manufacturing is simpler, but emissivity is insufficient for EUV lithography applications
Solution Approach 1:
The membrane incorporates EUV-reflective or EUV-transmissive functional layers (e.g., multilayer mirrors with alternating high-Z and low-Z materials, or specialized dielectric coatings) deposited on the porous substrate. These composite structures maintain manufacturability through established thin-film deposition techniques while achieving the high EUV emissivity (>70% reflectivity or transmissivity) required for EUV lithography applications.
Data Source
AI summary
A membrane for EUV lithography, the membrane having a thickness of no more than 200 nm and including a stack having: at least one silicon layer; and at least one silicon compound layer made of a compound of silicon and an element selected from the group consisting of boron, phosphorous, bromine.