Onium Salt Quencher Composition for EUV Resist Pattern Stability
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Solution Overview
Problem
Conventional chemically amplified resist compositions face challenges in suppressing acid diffusion, leading to reduced sensitivity, contrast, and lithographic performance issues such as exposure tolerance, line width roughness, critical dimension uniformity, and depth of focus, while also experiencing pattern collapse during fine pattern formation.
Innovation Solution
A novel onium salt comprising a sulfonium cation with a cyano group and an aromatic carboxylic acid anion containing an iodine atom is used as a quencher in a chemically amplified resist composition, enhancing solvent solubility and improving lithographic performances like exposure latitude, line width roughness, critical dimension uniformity, and depth of focus, while preventing pattern collapse.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If acid diffusion is reduced to improve resolution, then manufacturing precision is improved, but sensitivity deteriorates
Solution Approach 1:
The patent introduces a novel onium salt structure with specific parameters: a cation containing a cyano group and an anion containing an iodine atom. By changing the chemical structure parameters of the quencher, the patent achieves simultaneous improvement in resolution (through suppressed acid diffusion) and sensitivity (through enhanced solvent solubility provided by the iodine atom), resolving the traditional tradeoff between these two parameters.
2Manufacturing precision
If conventional onium salts are used as quenchers, then acid diffusion is suppressed, but pattern collapse occurs during fine pattern formation
Solution Approach 1:
The patent creates a composite quencher molecule by combining specific functional groups: a cation with a cyano group and an anion with an iodine atom. This composite structure integrates the acid diffusion suppression capability (from the onium salt core) with pattern stability enhancement (from the iodine atom's solvent solubility contribution), preventing pattern collapse while maintaining resolution.
3Ease of manufacture
If the quencher structure is simplified, then ease of manufacture is improved, but lithographic performance deteriorates
Solution Approach 1:
The patent optimizes the quencher structure by selecting specific substituent parameters (cyano group on cation, iodine atom on anion) that balance synthetic accessibility with performance. The cyano group and iodine atom are introduced at specific positions in the molecular structure, achieving excellent lithographic performance (exposure latitude, LWR, CDU, DOF) while maintaining reasonable ease of manufacture through straightforward synthetic routes.
Data Source
AI summary
The onium salt comprises a cation having the following formula (1A) and an anion having the following formula (1B). The onium salt can be used for a chemically amplified resist composition having high sensitivity, excellent resolution, and improved lithographic performances such as EL, LWR, CDU, and DOF and capable of suppressing resist pattern collapse particularly in photolithography using high-energy radiation such as far ultraviolet rays, electron beam (EB), and EUV.