Resist Composition with Trifluoromethyl Groups for Lithography
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Solution Overview
Problem
Current ArF resist compositions face challenges in achieving high resolution and sensitivity while maintaining balanced lithography properties such as line width roughness (LWR) and critical dimension uniformity (CDU) due to acid diffusion issues, particularly as circuit line widths decrease, and existing photo acid generators like sulfonium salts generate perfluorooctane sulfonic acid, which is toxic and difficult to decompose.
Innovation Solution
A resist composition incorporating a polymer compound with a repeating unit that generates a sulfonic acid structure upon high energy beam or heat exposure, featuring two trifluoromethyl groups at the β-position of the sulfo group to control acid diffusion, combined with a photo acid generator and nitrogen-containing compounds for improved sensitivity and substrate adhesion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional photo acid generators like sulfonium salts are used, then the resist composition can be formed, but the generated perfluorooctane sulfonic acid is toxic and difficult to decompose
Solution Approach 1:
The patent changes the chemical structure parameters of the photo acid generator by using fluorinated alkanesulfonic acid generators instead of conventional sulfonium salts. This structural parameter change results in the generation of perfluorobutane sulfonic acid, which has improved environmental safety and decomposability while maintaining the required lithography performance.
Solution Approach 2:
The patent employs a photo acid generator that generates perfluorobutane sulfonic acid, which is designed to be more easily decomposed than conventional generators. This disposable-like approach uses a generator that completes its function and can be readily broken down, avoiding the accumulation of toxic substances.
2Reliability
If photo acid generators generating perfluorobutane sulfonic acid are used, then environmental safety is improved, but the generated acid diffuses considerably and high resolution is difficult to achieve
Solution Approach 1:
The patent introduces a base compound as an intermediary substance that reacts with the generated perfluorobutane sulfonic acid to form a sulfonate ester. This intermediary reaction prevents direct acid diffusion and maintains resolution, while still allowing the benefits of using environmentally safe fluorinated sulfonic acid generators.
Solution Approach 2:
The patent modifies the chemical environment parameters by introducing base compounds that change the reactivity and mobility of the generated acid. This parameter change in the chemical environment allows the acid to be controlled and prevented from diffusing excessively, thereby maintaining high resolution.
3Use of energy by moving object
If highly sensitive resist composition is used to prevent degradation of optical material, then sensitivity is improved, but acid diffusion increases and LWR and CDU deteriorate
Solution Approach 1:
The patent uses base compounds as intermediary substances that react with generated acid to form less mobile sulfonate ester species. This intermediary reaction mechanism allows the resist composition to maintain high sensitivity while preventing the acid from causing excessive diffusion that would deteriorate LWR and CDU.
Solution Approach 2:
The patent creates a composite resist system combining the base resin with specific base compounds that modify acid behavior. This composite approach allows the system to achieve both high sensitivity and controlled acid diffusion, resolving the contradiction between sensitivity improvement and precision maintenance.
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 resolution and sensitivity with improved LWR and CDU, reducing acid diffusion and enhancing lithography properties, making it suitable for precise and fine patterning in photolithography.
Implementation Method 1
a polymer compound that changes by a high energy beam or heat into a polymer compound having a sulfonic acid structure
Implementation Method 2
various photo-sensitive acid generators have been studied. As the photo acid generator, sulfonium salts of triphenylsulfonium cation and perfluoroalkane sulfonate anion are commonly used
Data Source
AI summary
The present invention provides a compound shown by the formula (1),wherein R1 represents a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group; A represents a single bond or a linear divalent hydrocarbon group having 1 to 30 carbon atoms or a branched or cyclic divalent hydrocarbon group having 3 to 30 carbon atoms, in which the hydrocarbon group may contain a heteroatom, and a part or all of hydrogen atoms in the hydrocarbon group may be substituted with a group containing a heteroatom; “n” represents 0 or 1, provided that “n” is 0 when A is a single bond; and M+ represents a cation. This compound is suitable as a raw material of a polymer compound usable for a base resin of a resist composition that has high resolution and high sensitivity and is excellent in balance of lithography properties such as LWR and CDU.