Pellicle Membrane In-Plane Composition Variation EUV Lithography
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Solution Overview
Problem
Existing pellicle membranes for lithographic apparatuses, particularly those used in EUV lithography, face challenges in achieving high EUV transmissivity while maintaining structural integrity and controlling thermal properties, and they are not effective in filtering out undesired wavelengths of radiation, leading to potential damage and defects in the patterning device and substrate.
Innovation Solution
A pellicle membrane with in-plane variation in composition, featuring a grid of high emissivity material embedded within a more transmissive material, allowing for optimized EUV transmissivity and thermal control, and capable of filtering out undesired wavelengths by varying the pitch and ratio of materials.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If the pellicle thickness is reduced to increase EUV transmissivity, then the EUV transmissivity is improved, but the structural strength and ability to withstand hostile environment deteriorates
Solution Approach 1:
The pellicle is constructed as a composite structure comprising a substrate layer and a grid layer with different material properties. The substrate provides mechanical strength while the grid pattern provides thermal emission and filtration functions, allowing the pellicle to be thin yet structurally sound.
Solution Approach 2:
The grid layer is applied selectively in a pattern rather than uniformly across the entire pellicle surface. This localized application allows specific regions to have different properties (high emissivity at grid lines, high transmissivity in grid spaces) optimizing both structural and optical performance.
2Ease of manufacture
If a uniform pellicle material is used to simplify manufacturing, then the ease of manufacture is improved, but the ability to filter undesired wavelengths and control thermal properties deteriorates
Solution Approach 1:
The pellicle combines different materials (substrate material and grid material) with complementary properties. The substrate material provides mechanical support and baseline transmissivity, while the grid material provides thermal emission and spectral filtering, achieving multifunctionality through material composition.
Solution Approach 2:
Different regions of the pellicle have different material compositions - the substrate layer and the grid layer - allowing each region to perform its specific function while the overall structure achieves spectral filtering and thermal control capabilities.
3Strength
If the pellicle absorbs more EUV radiation to maintain structural integrity, then the strength is improved, but the operating temperature increases causing damage and defects
Solution Approach 1:
The composite structure allows separation of functions: the substrate provides structural integrity while the high-emissivity grid material handles thermal management by radiating absorbed energy, preventing excessive temperature rise in the structural support elements.
Solution Approach 2:
The grid material converts the harmful absorbed radiation into beneficial thermal emission. By providing high emissivity regions, the pellicle transforms absorbed EUV energy into radiated energy that can be managed, preventing heat accumulation that would otherwise damage the structure.
4Illumination intensity
If the pellicle is made thinner to reduce radiation absorption, then the EUV transmissivity is improved, but the reliability in harsh environment deteriorates
Solution Approach 1:
The thin pellicle achieves reliability through composite construction where the substrate provides mechanical strength despite reduced thickness, and the grid reinforcement provides additional structural support and functional properties, enabling the overall structure to withstand harsh EUV environment.
Solution Approach 2:
The grid pattern provides localized reinforcement and functionality in specific regions, allowing the pellicle to be thin overall while maintaining reliability at critical locations through the strategically placed grid structure.
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 pellicle membrane achieves high EUV transmissivity, reduced operating temperature, and prolonged lifespan, while effectively filtering out unwanted radiation, thereby enhancing image quality and preventing damage to the patterning device and substrate.
Implementation Method 1
it is necessary for the pellicle to have high EUV transmissivity. A high EUV transmissivity allows a greater proportion of the incident radiation through the pellicle
Implementation Method 2
reducing the amount of EUV radiation absorbed by the pellicle may decrease the operating temperature of the pellicle
Implementation Method 3
capable of filtering out undesired wavelengths by varying the pitch and ratio of materials
Data Source
AI summary
A pellicle membrane for use in a lithographic apparatus, the pellicle membrane characterized by in plane variation in composition is described. A method of manufacturing a pellicle membrane, the method including: providing a first material layer on a sacrificial layer on a substrate; providing a photoresist layer on the first material layer; patterning the photoresist layer; etching the first material layer to form a patterned surface; and either i) depositing a layer of a second material on the patterned surface and subsequently lifting off the portion of the second material deposited on the patterned photoresist layer, or ii) removing the remaining photoresist layer, depositing a layer of a second material on the patterned surface, and subsequently planarizing the surface.