CNT Pellicle Carbon Sheet Balancing EUV Transmittance and Stability
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Solution Overview
Problem
Existing photolithography pellicles face challenges in maintaining high ultraviolet transmittance and structural stability, especially under extreme ultraviolet (EUV) conditions, which can affect semiconductor production yield due to foreign substance attachment.
Innovation Solution
A carbon sheet for pellicles composed of bundles of carbon nanotubes with a specific porosity to linear density ratio of 0.2 to 10, optionally including metallic elements and elemental sulfur, manufactured through chemical vapor deposition at controlled temperatures and gas atmospheres, ensuring high UV transmittance and structural stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If the carbon sheet uses higher porosity to improve UV transmittance, then the transmittance increases, but the structural stability deteriorates
Solution Approach 1:
The patent optimizes the porosity to linear density ratio (P/D) within the specific range of 0.2 to 10, and controls porosity between 0.5 to 0.95, to simultaneously achieve high UV transmittance (90% or more at 13.5 nm) and structural stability for free-standing capability
Solution Approach 2:
The carbon sheet is composed of bundles of carbon nanotubes (single-walled, double-walled, or multi-walled types) with controlled morphology and composition, creating a composite structure that balances optical transparency and mechanical strength
2Illumination intensity
If the carbon sheet reduces linear density to improve flexibility and transmittance, then the transmittance improves, but the structural stability worsens
Solution Approach 1:
The patent specifies linear density D should be greater than 0.5 g/km and less than or equal to 2.8 g/km, optimizing the P/D ratio to maintain both high transmittance and sufficient strength for free-standing structure
Solution Approach 2:
The carbon nanotubes are arranged in bundles with specific diameter (10 nm to 100 nm), creating localized structural characteristics that provide both transparency and mechanical integrity
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 carbon sheet achieves ultraviolet transmittance of 90% or more at 13.5 nm wavelength while maintaining structural stability, preventing foreign substance attachment and enhancing semiconductor production yield.
Implementation Method 1
achieves high ultraviolet transmittance of 90 percent or more, particularly at a wavelength of 13.5 nanometers
Implementation Method 2
manufactured through chemical vapor deposition at controlled temperatures and gas atmospheres
Data Source
AI summary
Provided is a carbon sheet for pellicle that includes a bundle composed of a plurality of carbon nanotubes, and a ratio (P/D) of porosity P to linear density D (in grams per kilometer [g/km]) is within a range of 0.2 to 10. Also provided is a pellicle that includes the carbon sheet and a pellicle frame configured to support it. The carbon sheet is free-standing and exhibits excellent transmittance with respect to ultraviolet rays, including extreme ultraviolet radiation. Further provided is a method for manufacturing the carbon sheet, which includes forming the bundle of carbon nanotubes by reacting a source material under controlled conditions. This method enables the formation of a carbon sheet that maintains mechanical stability while achieving high ultraviolet transmittance, suitable for use in photolithography processes.