Resist Topcoat Copolymer for EUV Pattern Uniformity
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Solution Overview
Problem
Photolithographic processes face challenges in pattern integration due to EUV exposure causing pattern distribution deterioration such as roughness (LER, LWR) and IPU, primarily due to uneven EUV absorption across the photoresist depth.
Innovation Solution
A resist topcoat composition comprising a copolymer with specific structural units and a solvent, designed to react with excess activated acid, reducing pattern deterioration by minimizing EUV absorption disparities and enhancing pattern uniformity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If EUV exposure is used for photolithography, then high resolution patterns can be formed, but pattern distribution deterioration occurs due to photo shot noise and uneven EUV absorption
Solution Approach 1:
A topcoat layer comprising a copolymer and solvent is introduced as an intermediary between the EUV light source and the photoresist. This topcoat absorbs excess activated acid generated during EUV exposure, preventing it from causing pattern distribution deterioration in the photoresist while allowing high-resolution patterning to proceed
Solution Approach 2:
The invention converts the harmful effect of excess activated acid (which causes pattern deterioration) into a beneficial outcome by using the topcoat to selectively absorb this acid. The acid that would otherwise degrade pattern quality is instead captured by the copolymer's functional groups, improving overall pattern uniformity
2Ease of manufacture
If photoresist layer is coated for patterning, then pattern formation is enabled, but LER and LWR increase due to EUV absorption difference between top and bottom of photoresist
Solution Approach 1:
The topcoat serves as a protective intermediary layer that absorbs excess activated acid before it can penetrate into the photoresist. This prevents acid-induced degradation at the pattern edges, reducing LER and LWR while maintaining the photoresist's patterning functionality
3Productivity
If conventional photoresist composition is used, then basic patterning is achieved, but IPU deteriorates due to random light irradiation variations
Solution Approach 1:
The invention transforms the harmful random variations in light absorption into a controllable process by using the topcoat to uniformly absorb excess activated acid across the entire photoresist layer. This compensates for random light irradiation variations, improving in-point uniformity while maintaining patterning efficiency
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 composition effectively reduces LER, LWR, and IPU, enabling the formation of precise and uniform photoresist patterns, particularly in EUV exposure scenarios.
Implementation Method 1
the copolymer having an OH value of about 5 mgKOH/g to about 100 mgKOH/g... capable of removing excess activated acid from a top surface of the photoresist when exposed with extreme ultraviolet light
Implementation Method 2
when exposed with extreme ultraviolet light... EUV absorption difference between top and bottom of the photoresist may cause pattern distribution deterioration
Data Source
AI summary
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 at least one of Chemical Formula M-3A, Chemical Formula M-3B, or Chemical Formula M-3C; and a solvent, wherein the copolymer has an OHV (OH value) of about 5 mgKOH/g to about 100 mgKOH/g.