Graphene Quantum Dot Pellicle for EUV Transmittance
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Solution Overview
Problem
Current pellicle materials for photomasks in lithography processes lack high transmittance, especially for shorter wavelengths, and do not adequately combine high strength, durability, and stability, particularly when exposed to extreme ultraviolet light.
Innovation Solution
A pellicle composition incorporating graphene quantum dots with specific defect structures and functional groups, combined with a solvent, is used to form a pellicle membrane that enhances transmittance, strength, and durability by optimizing the carbon and oxygen content through thermal treatment and etching processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If conventional pellicle materials are used, then the photomask is protected from contaminants, but the transmittance for shorter wavelengths (EUV light) is insufficient
Solution Approach 1:
The patent changes the material parameters by incorporating graphene quantum dots with specific size ranges (5-50 nm) and controlling their concentration (0.1-40 wt%) in the pellicle composition. This parameter optimization enables high EUV transmittance while maintaining protective functionality, as the quantum dot size and concentration are tuned to allow EUV light passage while providing contaminant protection.
Solution Approach 2:
The patent creates a composite pellicle material combining graphene quantum dots with polymer matrices (such as PMMA, PS, or PI). This composite structure leverages the unique properties of graphene quantum dots - their high transmittance in EUV range and protective characteristics - to achieve both high EUV transmittance and reliable contaminant protection simultaneously.
2Illumination intensity
If the pellicle membrane is made thinner to improve transmittance, then EUV light transmission increases, but the strength and durability decrease
Solution Approach 1:
The patent optimizes the thickness parameter of the pellicle membrane to a specific range (10-100 nm) and combines it with controlled graphene quantum dot concentration (0.1-40 wt%). This parameter combination achieves high EUV transmittance while the graphene quantum dots provide structural reinforcement that maintains membrane strength despite the thin thickness required for optimal light transmission.
Solution Approach 2:
The composite structure of graphene quantum dots dispersed in a polymer matrix provides enhanced mechanical strength to the thin pellicle membrane. The graphene quantum dots act as reinforcing agents that prevent membrane rupture and degradation even at thicknesses optimized for EUV transmittance, thus resolving the contradiction between thinness for transmittance and thickness for strength.
3Strength
If graphene quantum dots with high carbon content are used to improve strength, then durability increases, but oxygen-containing functional groups needed for stability are reduced
Solution Approach 1:
The patent precisely controls the carbon content (70-95 atom%) and oxygen content (5-30 atom%) of graphene quantum dots within specific ranges. This parameter optimization ensures sufficient carbon content for high ultimate strength while maintaining adequate oxygen-containing functional groups for chemical stability and resistance to EUV light-induced degradation, thus balancing strength and stability requirements.
Solution Approach 2:
The patent introduces different types of oxygen-containing functional groups (carboxyl, hydroxyl, epoxy) at specific locations and concentrations within the graphene quantum dot structure. This local quality differentiation allows regions with higher carbon content for strength while maintaining functional groups distributed throughout for stability, resolving the contradiction between carbon content for strength and oxygen content for stability.
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 resulting pellicle membrane exhibits improved EUV transmittance, ultimate strength, and uniformity, effectively protecting photomasks from contaminants and maintaining structural integrity during lithography processes.
Implementation Method 1
The graphene quantum dot compound includes at least one selected from graphene quantum dots having a size of about 50 nm or less or a graphene quantum dot precursor
Implementation Method 2
a pellicle membrane including a product obtained by coating and thermally treating the pellicle composition
Data Source
Figure 1~3
Figure 4~5B
Figure 5C~5D
AI summary
A pellicle composition for a photomask, a pellicle for a photomask, the pellicle for a photomask being formed from the pellicle composition, a method of forming the pellicle, a reticle including the pellicle, and an exposure apparatus for lithography including the reticle are provided. The pellicle composition includes: at least one selected from graphene quantum dots and a graphene quantum dot precursor, the graphene quantum dots having a size of about 50 nm or less; and a solvent.