Bis-onium Salt Resist Composition for EUV Lithography
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Solution Overview
Problem
Current EUV lithography resist compositions face challenges in achieving high sensitivity while maintaining low line width roughness (LWR) and critical dimension uniformity (CDU), due to the tradeoff between sensitivity and acid diffusion control.
Innovation Solution
The use of a bis-onium salt as the acid generator and quencher, comprising a divalent anion with a sulfonic acid structure bonded to an iodized aromatic group and a carboxylic acid anion, which controls acid diffusion and enhances sensitivity, LWR, and CDU.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the PEB temperature is lowered to control acid diffusion, then LWR or CDU is improved, but sensitivity becomes lower
Solution Approach 1:
The patent changes the chemical parameters of the acid generator and quencher by introducing fluorine atoms at specific positions (alpha and beta positions relative to the carboxyl group) to modify acid strength and diffusion characteristics, allowing simultaneous optimization of sensitivity and LWR without temperature reduction
Solution Approach 2:
The patent uses a composite acid generator structure combining fluorinated aromatic ring systems with carboxyl groups and sulfonic acid moieties, creating a material that exhibits both high acid generation efficiency for sensitivity and controlled diffusion for LWR improvement
2Manufacturing precision
If the amount of quencher added is increased to control acid diffusion, then LWR or CDU is improved, but sensitivity becomes lower
Solution Approach 1:
The patent merges the acid generator and quencher into a single integrated molecule where the fluorinated aromatic ring system serves both functions: generating acid upon photoexcitation and simultaneously quenching to limit diffusion, eliminating the need to trade sensitivity for CDU improvement
Solution Approach 2:
The patent modifies the chemical structure by adding fluorine atoms at specific positions to change the electronic properties, enhancing both acid generation efficiency (for sensitivity) and acid diffusion control (for CDU) simultaneously through electronic effect modulation
3Manufacturing precision
If fluorine is introduced to enhance acid strength and resolution, then resolution is improved, but sensitivity may be affected
Solution Approach 1:
The patent applies fluorine substitution at specific local positions (alpha and beta positions relative to the carboxyl group) rather than throughout the entire molecule, creating localized electronic effects that enhance acid strength and diffusion control while preserving overall sensitivity through the fluorinated aromatic ring system's photoabsorption properties
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
This approach results in a resist composition with high sensitivity, reduced LWR, improved CDU, high contrast, high resolution, and a wide process margin, effectively addressing the tradeoff between sensitivity and acid diffusion.
Implementation Method 1
the efficiency of decomposition of the acid generator during exposure is increased, leading to a higher sensitivity
Implementation Method 2
Since iodine having high EUV absorption or bromine having high ionization efficiency is included, the efficiency of decomposition of the acid generator during exposure is increased
Implementation Method 3
control of acid diffusion is also important as reported in Non-Patent Document 1
Data Source
AI summary
A resist composition is provided comprising a bis-onium salt consisting of a divalent anion having a sulfonic acid anion structure directly bonded to an iodized aromatic group and a carboxylic acid anion structure bonded to the aromatic group directly or via a linking group, and onium cations. It exhibits a high sensitivity and forms a pattern with reduced LWR or improved CDU independent of whether it is of positive or negative type.