Resist Composition Using Iodized Onium Salt for EUV Lithography
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Solution Overview
Problem
Current resist compositions face challenges in achieving high sensitivity while minimizing line width roughness (LWR) and critical dimension uniformity (CDU) due to acid diffusion issues, particularly at smaller feature sizes, where reducing post-exposure bake temperature or increasing quencher amounts trade off sensitivity for improved LWR or CDU.
Innovation Solution
A resist composition utilizing an onium salt with an aromatic sulfonic acid anion having a linkage of two iodized or brominated aromatic groups as an acid generator, which absorbs EUV radiation effectively, reducing acid diffusion and enhancing sensitivity, LWR, and CDU.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the post-exposure bake temperature is lowered to reduce acid diffusion distance, then LWR or CDU is improved, but sensitivity becomes lower
Solution Approach 1:
The patent changes the chemical composition parameters of the acid generator by introducing fluorine atoms at the α-position and using specific anions (aryl sulfonates, carboxylates, phosphonates) to modify acid strength and diffusion characteristics. This allows achieving low LWR at higher PEB temperatures by fundamentally altering the acid generation properties rather than simply lowering temperature
Solution Approach 2:
The patent uses composite acid generator structures combining sulfonium or iodonium salts with fluorinated aryl sulfonate/carboxylate/phosphate anions. This composite approach creates a synergistic effect where the cation provides high EUV absorption and the fluorinated anion provides controlled acid strength and reduced diffusion, simultaneously improving sensitivity and LWR
2Manufacturing precision
If the amount of quencher is increased to reduce acid diffusion, then LWR or CDU is improved, but sensitivity becomes lower
Solution Approach 1:
The patent changes the quencher chemical structure by introducing fluorine atoms at the α-position of the carboxylic acid group. This fluorination increases acid strength and reduces quencher diffusion distance, allowing effective LWR control with lower quencher concentrations that preserve sensitivity
Solution Approach 2:
The fluorinated quencher acts as an improved intermediary between the acid generator and the polymer matrix. The fluorinated structure enhances the quencher's ability to localize acid generation while maintaining compatibility with the resist matrix, achieving better LWR control without sensitivity loss
3Productivity
If iodine or bromine is included in the acid generator to increase decomposition efficiency, then sensitivity is improved, but acid diffusion control becomes more difficult
Solution Approach 1:
The patent changes from iodine/bromine-based acid generators to fluorinated sulfonium/iodonium salts with aryl sulfonate anions. This parameter change maintains high EUV absorption (sensitivity) while the fluorinated anion structure provides better acid diffusion control through enhanced acid strength and reduced diffusion distance
Solution Approach 2:
The patent creates a composite acid generator system where the sulfonium or iodonium cation provides high EUV absorption efficiency for sensitivity, while the fluorinated aryl sulfonate anion provides controlled acid strength and reduced diffusion for LWR control. This composite structure resolves the contradiction between sensitivity enhancement and LWR control
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, improved LWR, and CDU, maintaining these performance metrics across both positive and negative tone patterns, independent of the tone type, with a wide process margin.
Implementation Method 1
an onium salt of aromatic sulfonic acid having a linkage of two iodized or brominated aromatic groups as an acid generator, which absorbs EUV radiation effectively
Data Source
AI summary
A resist composition comprises an onium salt of aromatic sulfonic acid having a linkage of two iodized or brominated aromatic groups as the acid generator is provided. The resist composition offers a high sensitivity, reduced LWR and improved CDU independent of whether it is of positive or negative tone. A pattern can be formed by using the resist composition.