Chemically Amplified Resist Composition Acid Diffusion Control
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Solution Overview
Problem
Current chemically amplified resist compositions face challenges in achieving rectangular profile patterns with improved line edge roughness (LER), resolution, fidelity, and dose margin due to uncontrolled acid diffusion, especially in advanced lithography processes like EUV and EB lithography, where acid diffusion affects sensitivity and resolution.
Innovation Solution
A chemically amplified positive resist composition incorporating a quencher in the form of an onium salt with a nitrogen-containing aliphatic heterocycle and an aromatic carboxylic acid structure, which effectively controls acid diffusion by trapping strong acids and enhancing solubility in alkaline developers, thereby improving pattern formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If acid-decomposable protective groups requiring low activation energy (e.g., acetal groups) are used to achieve high sensitivity, then resist sensitivity is improved, but acid diffusion occurs in unexposed regions causing increased LER and degraded CDU
Solution Approach 1:
A base polymer with basic functional groups (e.g., carboxylic acid groups) is introduced as an intermediary substance between the photoacid generator and the acid-labile protective groups. This base polymer acts as an acid trap that preferentially neutralizes diffusing photoacids, preventing them from reaching unexposed regions and causing premature deprotection. The base polymer thus mediates the interaction between generated acids and protective groups, enabling high sensitivity while maintaining pattern fidelity.
2Productivity
If conventional photoacid generators are used to achieve high sensitivity, then exposure efficiency is improved, but uncontrolled acid diffusion reduces pattern resolution and increases LER
Solution Approach 1:
The base polymer serves as an intermediary acid-trapping component that is distributed throughout the resist film. When photoacids are generated by conventional photoacid generators, the base polymer intercepts and neutralizes diffusing acids before they can cause unwanted reactions in unexposed areas. This intermediary mechanism allows the use of high-efficiency photoacid generators while maintaining sharp pattern boundaries and low LER.
3Measurement precision
If high concentration of photoacid generator is used to improve sensitivity, then exposure efficiency increases, but acid diffusion distance increases causing loss of resolution
Solution Approach 1:
The base polymer is distributed throughout the resist film at concentrations designed to intercept photoacids within a limited diffusion distance from generation sites. By placing this intermediary acid-trapping component throughout the medium, the effective acid diffusion distance is reduced even when high concentrations of photoacid generator are used, thereby maintaining both high sensitivity and sharp pattern definition.
4Manufacturing precision
If existing quencher structures are used to control acid diffusion, then some LER improvement is achieved, but insufficient control over acid diffusion remains and pattern fidelity is not optimized
Solution Approach 1:
The invention changes the chemical parameters of the acid-trapping component by using base polymers with specific basic functional groups (e.g., carboxylic acid groups with pKa values in specific ranges). This parameter change enables more effective and controllable acid neutralization compared to existing quencher structures, achieving both low LER and high pattern fidelity through optimized acid-base interactions.
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, high-fidelity patterns with reduced LER and improved dose margin, effectively addressing the limitations of existing compositions by controlling acid diffusion and enhancing adhesion and solubility, making it suitable for advanced micropatterning technologies.
Implementation Method 1
incorporating a quencher in the form of an onium salt with a nitrogen-containing aliphatic heterocycle and an aromatic carboxylic acid structure, which effectively controls acid diffusion by trapping strong acids
Implementation Method 2
Upon exposure to high-energy radiation, the acid-decomposable protective group is deprotected by the catalysis of an acid generated from a photoacid generator so that the polymer may turn soluble in alkaline developer
Data Source
AI summary
A chemically amplified positive resist composition is provided comprising (A) a quencher containing an onium salt having a nitrogen-containing aliphatic heterocycle and an aromatic carboxylic acid structure in its anion and (B) a base polymer containing a specific polymer which is decomposed under the action of acid to increase its solubility in alkaline developer. The resist composition exhibits a high resolution during pattern formation and forms a pattern of rectangular profile with improved LER, fidelity and dose margin.