DUV Filtering Coating Composition for EUV Lithography
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Solution Overview
Problem
Current methods for forming fine patterns in semiconductor devices using extreme ultraviolet (EUV) lithography are hindered by the presence of out-of-band deep ultraviolet (DUV) light, which affects resolution and pattern variance, as they do not effectively filter out DUV wavelengths.
Innovation Solution
A coating composition for DUV filtering is developed, comprising an alcohol-based solvent and a coating polymer with a high degree of absorption for 193-nm wavelength light, applied in a method that includes forming a photoresist pattern and using it as an etch mask for semiconductor device fabrication, thereby blocking out-of-band DUV light.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If EUV lithography is used to form fine patterns, then pattern fineness is improved, but out-of-band DUV light causes resolution degradation and pattern variance
Solution Approach 1:
A coating layer comprising a coating polymer and solvent is applied between the EUV light source and the photoresist pattern. This intermediary layer selectively absorbs out-of-band DUV light while transmitting EUV light, thereby resolving the contradiction by filtering harmful wavelengths without affecting the desired EUV exposure process
Solution Approach 2:
The coating polymer is specifically selected to have high absorption coefficient for DUV wavelengths (193nm, 248nm, 365nm) while maintaining transparency to EUV wavelengths. By changing the optical parameters of the intermediate layer, the system achieves selective wavelength filtering that improves pattern resolution while eliminating DUV interference
2Object-affected harmful factors
If a coating polymer with high DUV absorption is used, then DUV filtering performance is improved, but the coating composition becomes more complex
Solution Approach 1:
The coating composition is formulated as a composite material combining specifically selected coating polymers (such as polyhydroxystyrene, novolac resin, or their copolymers) with compatible solvents. This composite approach achieves high DUV absorption while maintaining proper coating properties, resolving the complexity issue through systematic material design rather than simple additive mixing
Solution Approach 2:
The molecular structure of the coating polymer is optimized by adjusting the ratio of hydroxystyrene units to other monomer units, and by selecting appropriate molecular weights and polydispersity indices. These parameter changes enable tuning of both DUV absorption performance and coating processability, achieving high filtering capability without excessive composition complexity
3Object-affected harmful factors
If the coating polymer concentration is increased to improve DUV absorption, then filtering effectiveness is improved, but coating uniformity and film quality may deteriorate
Solution Approach 1:
The concentration of coating polymer in the composition is optimized within a specific range (0.01-10 wt%, preferably 0.1-5 wt%). Additionally, the molecular weight and polydispersity of the polymer are controlled, and the solvent ratio is adjusted to maintain proper viscosity and coating uniformity. These coordinated parameter changes achieve high DUV absorption while preserving film quality
Solution Approach 2:
The coating composition uses a composite system of polymer and solvent in optimized proportions, where the solvent acts as a dispersing medium that maintains uniform distribution of polymer chains even at higher concentrations. This composite formulation allows high polymer content for effective DUV filtering without sacrificing coating film uniformity
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 solution improves pattern resolution and variance by effectively filtering out DUV light, allowing for precise formation of fine patterns and accurate semiconductor device fabrication.
Implementation Method 1
a coating polymer having a degree of absorption of about 50%/μm or greater with respect to 193-nm wavelength incident light
Data Source
AI summary
Provided are a coating composition for deep ultraviolet (DUV) filtering during an extreme ultraviolet (EUV) exposure, the coating composition including about 100 parts by weight of a solvent including a first solvent (the first solvent being an alcoholic solvent); and about 0.05 parts by weight to about 5 parts by weight of a coating polymer having a degree of absorption of about 50%/μm or greater with respect to 193-nm incident light.