Fluorinated Sulfonic Acid Resist Composition for EUV LWR and CDU
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Solution Overview
Problem
EUV resist materials face a tradeoff between sensitivity and low edge roughness (LWR) and critical dimension uniformity (CDU), with existing acid generators failing to adequately control acid diffusion, leading to degraded resist patterns.
Innovation Solution
A resist composition using a sulfonium or iodonium salt of fluorinated sulfonic acid with a phenylene group substituted by a fluorinated cyclic group and a nitro group, which controls acid diffusion and enhances sensitivity, resulting in minimal LWR and improved CDU.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the PEB temperature is lowered to reduce LWR, then LWR is reduced, but sensitivity becomes lower
Solution Approach 1:
The patent changes the chemical parameters of the acid generator by introducing a fluorinated cyclic group with specific fluorine substitution patterns and a nitro group. This chemical parameter change enables the acid generator to maintain high acid generation efficiency at lower PEB temperatures, thus improving LWR without sacrificing sensitivity. The fluorinated structure modifies the thermal and chemical properties of the acid generator, allowing it to function effectively under optimized processing conditions.
Solution Approach 2:
The acid generator combines multiple functional groups (fluorinated cyclic group, nitro group, and sulfonic acid group) into a composite molecular structure. This composite structure integrates the benefits of fluorine atoms for EUV absorption with the nitro group's ability to control acid diffusion, achieving both high sensitivity and low LWR through the synergistic effect of different functional components within a single molecule.
2Manufacturing precision
If the amount of quencher added is increased to reduce LWR, then LWR is reduced, but sensitivity becomes lower
Solution Approach 1:
The patent extracts the acid diffusion control function from the quencher and relocates it to the acid generator molecule itself through the nitro group. This eliminates the need for additional quencher components and their associated negative effects on sensitivity. The acid generator now performs dual functions: generating acid and controlling its diffusion, thereby improving LWR without requiring increased quencher amounts that would reduce sensitivity.
Solution Approach 2:
The nitro group acts as an intermediary element within the acid generator structure that mediates acid diffusion control. Instead of using external quenchers that interfere with the photochemical process, the nitro group provides internal control of acid diffusion, achieving LWR improvement while maintaining high sensitivity by not introducing foreign substances that would absorb photons or interfere with acid generation.
3Productivity
If fluorine atoms are added to absorb EUV and increase acid generation efficiency, then sensitivity is improved, but acid diffusion expands and LWR or CDU degrades
Solution Approach 1:
The patent applies local quality by positioning fluorine atoms specifically at the cyclic group structure rather than throughout the entire molecule. This localized fluorination provides EUV absorption and acid generation efficiency while the nitro group at a different location controls acid diffusion. The spatial separation of these functions within the molecular structure allows each group to perform its specific role without the negative effects of the other.
Solution Approach 2:
The acid generator employs an asymmetric molecular structure where the fluorinated cyclic group and nitro group are positioned at different locations relative to the sulfonic acid group. This asymmetric arrangement creates distinct functional zones: the fluorinated region for photon absorption and acid generation, and the nitro group region for acid diffusion control. The asymmetry enables independent optimization of sensitivity and LWR through spatial separation of functions.
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 achieves high sensitivity, minimal LWR, and improved CDU, with enhanced dissolution contrast and uniform acid diffusion, applicable to both positive and negative tone patterns.
Implementation Method 1
acid generators capable of generating acids having a fluorinated ring... fluorinated acid generators show a high acid generating efficiency upon EUV exposure
Implementation Method 2
since fluorine atoms are able to absorb EUV, fluorinated acid generators show a high acid generating efficiency upon EUV exposure
Implementation Method 3
the acid diffusion distance is reduced, but sensitivity becomes lower... It is necessary to control the acid diffusion
Data Source
AI summary
A resist composition comprising a base polymer and an acid generator in the form of a sulfonium or iodonium salt of a fluorinated sulfonic acid having a phenylene group which is substituted with a fluorinated cyclic group and a nitro group is provided. The resist composition offers a high sensitivity, reduced LWR and improved CDU independent of whether it is of positive or negative tone.