CNT Pellicle Carbon Sheet Balancing UV Transmittance and Stability
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Solution Overview
Problem
Existing photolithography processes face challenges in maintaining high transmittance of ultraviolet (UV) rays while protecting photomasks from foreign substances, which can lead to decreased production yield of semiconductor chips.
Innovation Solution
A carbon sheet for pellicle composed of a bundle of carbon nanotubes with a specific porosity-to-linear density ratio, supported by a pellicle frame, providing excellent UV transmittance and free-standing capability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a carbon sheet with high porosity is used to achieve free-standing capability, then the structural stability deteriorates
Solution Approach 1:
The patent applies parameter changes by precisely controlling the porosity-to-linear density ratio (P/D) within the range of 0.2 to 10. This parameter optimization enables the carbon sheet to achieve free-standing capability while maintaining sufficient structural stability. The specific porosity range (0.5 to 0.95) and linear density range (0.5 to 2.8 g/km) are carefully selected to balance these conflicting requirements.
Solution Approach 2:
The patent employs composite materials by combining carbon nanotubes with specific metallic elements and elemental sulfur. This composite structure enhances both the free-standing capability and structural stability of the carbon sheet, resolving the contradiction between high porosity requirements and structural integrity needs.
2Illumination intensity
If the linear density is reduced to improve UV transmittance, then the mechanical strength deteriorates
Solution Approach 1:
The patent resolves this contradiction through parameter changes by maintaining linear density within the specific range of 0.5 to 2.8 g/km. This optimized parameter range ensures high UV transmittance while preventing mechanical strength deterioration. The porosity-to-linear density ratio control (P/D = 0.2 to 10) further fine-tunes this balance.
Solution Approach 2:
The composite material composition including carbon nanotubes, metallic elements, and elemental sulfur provides enhanced mechanical strength at reduced linear density, enabling both high UV transmittance and adequate mechanical strength to be achieved simultaneously.
3Illumination intensity
If the porosity is increased to enable free-standing structure, then the UV transmittance improves but the structural integrity worsens
Solution Approach 1:
The patent applies parameter changes by controlling porosity within the range of 0.5 to 0.95 and maintaining the porosity-to-linear density ratio (P/D) between 0.2 and 10. This precise parameter control allows the carbon sheet to achieve high UV transmittance through increased porosity while maintaining sufficient structural integrity through the optimized P/D ratio.
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 ensures high transmittance of UV rays and protects photomasks from foreign substances, enhancing the production yield of semiconductor chips by preventing interference with mask patterns.
Implementation Method 1
excellent transmittance over ultraviolet (UV) rays
Implementation Method 2
forming a bundle composed of a plurality of carbon nanotubes by reacting a source material including a carbon source
Data Source
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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 ([g/km]) is in a range of 0.2 to 10, and provided is a pellicle and a method of manufacturing a carbon sheet for pellicle that is free-standing and have an excellent transmittance against UV rays.