Iodinated Onium Salt Resist Composition for Acid Diffusion Control
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Solution Overview
Problem
Existing chemically amplified resist compositions face challenges in achieving high sensitivity, resolution, and lithography properties such as exposure latitude (EL), line width roughness (LWR), critical dimension uniformity (CDU), and depth of focus (DOF) while minimizing acid diffusion and preventing pattern collapse during the formation of small-size patterns.
Innovation Solution
Incorporation of an onium salt with an aromatic carboxylic acid anion containing a partial structure of iodine and a cyclic ether into a chemically amplified resist composition, which acts as a quencher to control acid diffusion and enhance solvent solubility, thereby improving sensitivity, resolution, and preventing pattern collapse.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If acid diffusion is suppressed by reducing temperature and/or time of post-exposure bake, then resolution is improved, but sensitivity and contrast are drastically reduced
Solution Approach 1:
The patent changes the chemical parameters of the acid generator by using a sulfonium salt with specific structural features (formula 1) that generates a sulfonic acid with controlled diffusion characteristics. The structural parameters R1-R6 are optimized to balance acid strength and diffusion control, resolving the contradiction between resolution and sensitivity
Solution Approach 2:
The patent creates a composite resist composition combining the sulfonium salt acid generator (formula 1) with specific base polymers having carboxylic acid groups. This composite system achieves synergistic effects where the acid generator provides controlled acid diffusion for resolution while the polymer matrix maintains sensitivity and contrast
2Manufacturing precision
If an acid generator capable of generating a bulky acid is used to suppress acid diffusion, then resolution is improved, but the complexity of the resist composition increases
Solution Approach 1:
The patent applies local quality by designing the sulfonium salt with specific local structural features (R1-R6 groups in formula 1) that create a bulky acid structure at the molecular level. This localized structural optimization suppresses acid diffusion without requiring complex overall composition design
Solution Approach 2:
The patent optimizes the structural parameters of the sulfonium salt (formula 1) to generate a sulfonic acid with specific bulk properties. By adjusting R1-R6 to be hydrogen or specific small groups, the acid achieves optimal bulk characteristics that suppress diffusion while keeping the composition relatively simple
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 onium salt-based resist composition exhibits high sensitivity, high contrast, improved lithography properties, and collapse resistance, resulting in reduced line width roughness and enhanced critical dimension uniformity of small-size patterns.
Implementation Method 1
the control of acid diffusion is also important as reported in Non-Patent Document 1. Since chemically amplified resist compositions are designed such that sensitivity and contrast are enhanced by acid diffusion, an attempt to minimize acid diffusion by reducing the temperature and/or time of post-exposure bake (PEB) fails
Implementation Method 2
In one aspect, the invention provides an onium salt consisting of an aromatic carboxylic acid anion including a partial structure having iodine and a cyclic ether structure and an onium cation
Data Source
AI summary
An onium salt consisting of an aromatic carboxylic acid anion including a partial structure having iodine and a cyclic ether structure and an onium cation is provided. When processed by photolithography using high-energy radiation, a chemically amplified resist composition comprising the onium salt has advantages including high sensitivity, high resolution, improved lithography properties, and collapse resistance.