Chemically Amplified Resist Composition for Low Acid Diffusion
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Solution Overview
Problem
Existing resist compositions in photolithography face challenges in achieving high resolution, sensitivity, and suppressing acid diffusion, leading to degraded lithography properties such as LWR, CDU, MEF, EL, and DOF, and pattern collapse during the formation of small-size patterns.
Innovation Solution
A chemically amplified resist composition using a betaine onium salt with aromatic sulfonic acid anions substituted with iodine and sulfonium cations, which enhances solvent solubility, sensitivity, and suppresses acid diffusion, improving lithography properties like LWR, CDU, MEF, EL, and DOF.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional photoacid generators (sulfonium salts with perfluoroalkanesulfonic acid anions) are used, then high sensitivity is achieved, but acid diffusion occurs leading to degraded resolution and lithography properties
Solution Approach 1:
The patent changes the molecular structure parameters of the photoacid generator by introducing a betaine structure with specific cation and anion sites separated by a linking group. This structural parameter change reduces acid diffusion while maintaining sensitivity, resolving the contradiction between resolution and acid diffusion.
Solution Approach 2:
The patent creates a composite photoacid generator molecule combining a sulfonium cation site with an aromatic sulfonic acid anion site, linked by a connecting group. This composite structure integrates the benefits of both cationic and anionic components, achieving low acid diffusion and high sensitivity simultaneously.
2Manufacturing precision
If fluorine-containing photoacid generators are used to reduce acid diffusion, then resolution improves, but environmental safety and decomposability deteriorate due to lack of decomposable substituents
Solution Approach 1:
The patent changes the chemical composition parameters by replacing persistent fluorine atoms with decomposable aromatic sulfonic acid groups while maintaining the low acid diffusion property through the betaine structure. This allows resolution improvement without compromising environmental safety.
Solution Approach 2:
The patent employs an aromatic sulfonic acid anion that can decompose more easily than persistent fluorinated compounds, making the photoacid generator environmentally friendlier while still achieving the desired low acid diffusion and high resolution performance.
3Manufacturing precision
If high exposure dose is used to achieve sufficient resolution, then optical system material degradation increases
Solution Approach 1:
The patent changes the photoacid generator structure to a betaine configuration with separated cation and anion sites, which enhances sensitivity by reducing acid diffusion. This allows achieving high resolution at lower exposure doses, thereby preventing degradation of expensive optical system materials.
4Manufacturing precision
If positive tone resist is used with aqueous alkaline development, then high resolution is achieved, but negative pattern formation capability is lost
Solution Approach 1:
The patent develops a resist composition that can form both positive and negative patterns depending on the development method used. The betaine photoacid generator enables this multi-functionality by providing controlled acid diffusion that works with both aqueous alkaline and organic solvent developers, achieving high resolution in both positive and negative tone applications.
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 contrast, good sensitivity, and improved lithography properties, including reduced pattern collapse, when processed by high-energy radiation like KrF or ArF excimer laser radiation, electron beam, or EUV.
Implementation Method 1
a photoacid generator comprising the onium salt
Implementation Method 2
suppresses acid diffusion
Data Source
AI summary
The onium salt has the formula (1). The chemically amplified resist composition comprising the onium salt as a photoacid generator. The chemically amplified resist composition has a high solvent solubility, a high sensitivity, and a high contrast, and being improved in lithography properties such as LWR, CDU, MEF, EL, and DOF, particularly when processed by photolithography using high-energy radiation such as KrF or ArF excimer laser radiation, an electron beam (EB) or EUV.