Iodinated Onium Salt Resist Composition for Acid Diffusion Suppression
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Solution Overview
Problem
Conventional resist compositions using onium salts fail to adequately suppress acid diffusion, leading to degraded lithography properties such as contrast, line width roughness (LWR), critical dimension uniformity (CDU), mask error factor (MEF), exposure latitude (EL), and depth of focus (DOF), particularly in high-energy radiation photolithography processes.
Innovation Solution
An onium salt with an aromatic sulfonic acid anion containing an acid labile group and iodine on an aromatic ring, free of fluorine, is used in a chemically amplified resist composition to enhance solvent solubility, sensitivity, and inhibit acid diffusion, improving lithography properties like LWR, CDU, MEF, EL, and DOF.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional onium salts are used in resist composition, then the resist can be manufactured with existing materials, but acid diffusion is not adequately suppressed leading to degraded lithography properties
Solution Approach 1:
The patent changes the chemical parameters of the onium salt by introducing specific structural features: an acid-labile group (formula AL-1 or AL-2) and iodine atoms on the aromatic ring. These parameter changes in the molecular structure suppress acid diffusion while maintaining manufacturability with existing materials and processes.
Solution Approach 2:
The patent creates a composite onium salt structure combining multiple functional elements: the onium cation, aromatic sulfonic acid anion, acid-labile group, and iodine atoms. This composite structure achieves both acid diffusion suppression and good solubility, resolving the contradiction between reliability and harmful factors.
2Object-generated harmful factors
If fluorine-containing onium salts are used to suppress acid diffusion, then acid diffusion is reduced, but solvent solubility and environmental safety are compromised
Solution Approach 1:
The patent extracts the fluorine atoms from the onium salt structure while retaining the essential acid diffusion suppression function. By removing fluorine and replacing it with iodine and acid-labile groups, the patent eliminates environmental safety concerns and improves solvent solubility while maintaining the benefit of reduced acid diffusion.
Solution Approach 2:
The patent replaces expensive fluorine-containing compounds with more economical iodine-containing onium salts that are easier to manufacture and dispose of, reducing both cost and environmental impact while achieving the same functional effect of acid diffusion suppression.
3Manufacturing precision
If the resist material is designed for high resolution with small feature sizes, then pattern precision is improved, but acid diffusion degradation becomes more serious
Solution Approach 1:
The patent applies preliminary anti-action by incorporating iodine atoms and acid-labile groups into the onium salt structure before exposure. These structural features pre-establish resistance against acid diffusion, preventing the degradation that would normally occur when forming small-size patterns with high precision requirements.
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, high contrast, and improved lithography properties, minimizing pattern collapse during the formation of small-size patterns.
Implementation Method 1
a chemically amplified resist composition comprising the onium salt as a photoacid generator which is capable of generating acid upon light exposure
Data Source
AI summary
An onium salt containing an aromatic sulfonic acid anion having an acid labile group and iodine on an aromatic ring, but not fluorine is provided. A chemically amplified resist composition comprising the onium salt as a photoacid generator has satisfactory solvent solubility, high sensitivity, and high contrast, and forms a resist film with improved lithography properties including EL and LWR.