Iodine-Containing Resist Composition for EUV Lithography
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Solution Overview
Problem
Current EUV lithography techniques face challenges in achieving high resolution and low edge roughness due to variations in photon number, leading to degraded line patterns and critical dimension uniformity, which existing resist compositions fail to adequately address.
Innovation Solution
A positive resist composition is developed using a base polymer with recurring units containing iodine and amino groups, combined with carboxyl or phenolic hydroxyl groups substituted with acid labile groups, to enhance acid generation efficiency and minimize acid diffusion, thereby improving sensitivity, resolution, and pattern profile.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the resist is made more absorptive to increase photons absorbed, then sensitivity improves, but edge roughness and critical dimension uniformity deteriorate due to photon number variation
Solution Approach 1:
The patent changes the chemical composition parameters of the resist by incorporating iodine-containing compounds (such as iodonium salts or iodinated polymers) which have high absorption coefficients at EUV wavelengths. This allows the resist to absorb sufficient photons at 13.5 nm wavelength, improving sensitivity while the specific chemical structure controls acid diffusion to maintain pattern fidelity
Solution Approach 2:
The patent uses composite resist formulations combining iodine-containing absorption enhancers with acid generators and quenchers in specific ratios. This composite approach optimizes both photon absorption and acid diffusion control, achieving high sensitivity while maintaining low edge roughness and good critical dimension uniformity
2Ease of manufacture
If conventional resist compositions are used, then manufacturing process is simple, but resolution and pattern quality are insufficient for next-generation devices
Solution Approach 1:
The patent modifies the chemical composition parameters by introducing iodine-containing compounds as key additives to conventional resist formulations. This parameter change enables the resist to achieve high resolution and low edge roughness required for 7-nm and 5-nm node devices while maintaining compatibility with existing EUV lithography processes
Solution Approach 2:
The patent introduces iodine-containing compounds as intermediary substances that mediate between the EUV photons and the acid generator. These compounds absorb EUV photons and transfer energy to generate acid, enabling high-resolution patterning while the acid diffusion control mechanisms preserve pattern fidelity
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 resist composition achieves high sensitivity, high resolution, and reduced edge roughness and size variation, making it suitable for forming fine patterns in VLSIs and photomasks with improved acid diffusion suppression.
Implementation Method 1
Among the halogen atoms, iodine is highly absorptive to EUV radiation of wavelength 13.5 nm
Implementation Method 2
an acid generator is sensitive to a small dose of photons
Implementation Method 3
Since iodine has a large atomic weight, quenchers in the form of iodized compounds are fully effective for suppressing acid diffusion
Data Source
AI summary
A positive resist composition comprising a base polymer comprising recurring units containing an optionally substituted amino group and iodine exhibits a high sensitivity, high resolution, low edge roughness (LER, LWR) and small size variation, and forms a pattern of good profile after exposure and development.