Onium Salt Photoacid Generator for Low-Diffusion Resist Patterning
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional onium salt-type photoacid generators fail to adequately suppress acid diffusion, leading to degradation of lithography performance such as contrast, line width roughness (LWR), critical dimension uniformity (CDU), mask error factor (MEF), exposure latitude (EL), and depth of focus (DOF) in high-resolution resist patterns.
Innovation Solution
An onium salt comprising a specific anion and cation structure, represented by general formulas (1A) and (1B), which enhances solvent solubility, sensitivity, and lithography performance by incorporating a hydrocarbyl group with an aromatic ring and a sulfonium cation with a cyano group, used in a chemically amplified resist composition.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional onium salt-type photoacid generators are used, then the resist composition can be formulated with existing materials, but acid diffusion is not adequately suppressed leading to degradation of lithography performance
Solution Approach 1:
The patent modifies the molecular structure of the onium salt by introducing specific fluorinated groups and aromatic hydrocarbyl substituents. These structural parameter changes increase the steric bulk and hydrophobicity around the photoacid generator, effectively suppressing acid diffusion while maintaining photolability and solubility in the resist matrix.
Solution Approach 2:
The invention creates a composite photoacid generator structure combining fluorinated alkyl chains with aromatic hydrocarbyl groups attached to the onium salt core. This composite structure leverages the acid-diffusion-suppressing effect of fluorinated groups while the aromatic groups provide solubility and structural stability, achieving both suppressed acid diffusion and good lithography performance.
2Manufacturing precision
If fluorinated photoacid generators are used to suppress acid diffusion, then resolution improves, but environmental safety deteriorates due to difficulty of decomposition and bioconcentration
Solution Approach 1:
The patent optimizes the fluorination pattern by using partially fluorinated alkyl chains rather than fully fluorinated structures. This parameter change reduces the persistence and bioconcentration potential while maintaining sufficient acid-diffusion-suppressing effect for high-resolution patterning.
Solution Approach 2:
The aromatic hydrocarbyl groups serve as intermediary structures that provide alternative decomposition pathways. These groups can undergo oxidative degradation and other environmental breakdown processes more readily than fully fluorinated structures, acting as a bridge between the fluorinated acid-diffusion-suppressing moieties and environmental safety requirements.
3Productivity
If the resist composition is optimized for high sensitivity, then exposure efficiency improves, but acid diffusion increases making it difficult to achieve high resolution
Solution Approach 1:
The patent segments the photoacid generator molecule into distinct functional regions: a photolabile onium core for acid generation, fluorinated alkyl chains for acid diffusion suppression, and aromatic hydrocarbyl groups for solubility. This segmentation allows each region to independently optimize its function without interfering with the others, achieving both high sensitivity and low acid diffusion.
Solution Approach 2:
The invention applies local quality by concentrating acid-diffusion-suppressing fluorinated groups in specific spatial regions around the photoacid generator core. This localized placement ensures that acid diffusion is suppressed in the critical regions near the exposure site while maintaining overall molecular solubility and photoreactivity.
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 excellent solvent solubility, high sensitivity, and superior lithography performance, effectively suppressing acid diffusion and improving LWR, CDU, MEF, EL, and DOF, enabling the formation of fine patterns with reduced pattern collapse.
Implementation Method 1
a photoacid generator (A) having an onium salt structure
Data Source
AI summary
The present invention is an onium salt, wherein the onium salt includes an anion represented by the following general formula (1A) and a cation represented by the following general formula (1B). This provides: an onium salt used as a photoacid generator contained in a chemically amplified resist composition having excellent solvent solubility, high sensitivity, high contrast, and excellent lithography performance in photolithography using high-energy beams; a photoacid generator consisting of the onium salt; a chemically amplified resist composition containing the photoacid generator; and a patterning process using the chemically amplified resist composition.