Resist Topcoat Copolymer for EUV Pattern Dispersion Control
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Solution Overview
Problem
Existing photolithographic processes face challenges in reducing pattern dispersion, particularly due to EUV irradiation, which causes roughness and in-point uniformity issues in semiconductor patterns.
Innovation Solution
A resist topcoat composition is developed, comprising a copolymer with specific structural units that absorb EUV light and selectively reduce acid concentration at the photoresist surface, thereby improving pattern uniformity and reducing roughness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If EUV irradiation is applied to photoresist, then pattern formation capability is improved, but pattern dispersion deteriorates due to photo shot noise and EUV absorption differences
Solution Approach 1:
A topcoat layer comprising a copolymer of formula (1) is introduced as an intermediary between the EUV light source and the photoresist. This topcoat selectively absorbs excess activation energy and radicals generated during EUV exposure, preventing them from reaching and damaging the photoresist surface. The topcoat thus mediates the interaction between EUV radiation and photoresist, enabling fine pattern formation while maintaining pattern dispersion.
Solution Approach 2:
The patent modifies the chemical composition and molecular weight of the copolymer in the topcoat to optimize its EUV absorption characteristics. By controlling the molecular weight between crosslinks (1,000-50,000 g/mol) and the specific ratio of structural units in the copolymer, the topcoat's ability to absorb EUV energy is tuned to match the requirements for reducing photo shot noise while maintaining transparency for pattern formation.
2Length of moving object
If photoresist layer is made thinner to achieve finer patterns, then pattern size is reduced, but pattern dispersion deteriorates due to increased EUV absorption differences between top and bottom
Solution Approach 1:
The topcoat serves as a protective intermediary that compensates for the increased EUV absorption gradients in thinner photoresist layers. By positioning the topcoat at the surface, it absorbs the excessive energy before it can create significant absorption differences through the thin photoresist, thereby maintaining pattern dispersion even as photoresist thickness is reduced for finer patterns.
Solution Approach 2:
The topcoat performs preliminary absorption of EUV energy and generation of acid at the surface before the radiation penetrates deeper into the photoresist. This preliminary action redistributes the energy deposition profile, reducing the absorption differences between top and bottom regions of the photoresist layer and preventing pattern dispersion deterioration.
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 topcoat composition effectively reduces pattern dispersion, significantly improves in-point uniformity of pillar patterns, and enhances the sensitivity of the photoresist, leading to the formation of finer and more uniform semiconductor patterns.
Implementation Method 1
a copolymer including a first structural unit represented by Chemical Formula M-1, a second structural unit represented by Chemical Formula M-2, and a third structural unit represented by Chemical Formula M-3A or Chemical Formula M-3B
Data Source
AI summary
Provided are a resist topcoat composition and a method of forming patterns using the resist topcoat composition, the resist topcoat composition including a copolymer including a first structural unit represented by Chemical Formula M-1, a second structural unit represented by Chemical Formula M-2, and a third structural unit represented by Chemical Formula M-3A or Chemical Formula M-3B; and a solvent.