Sulfonium Salt Photoacid Generator for Resist Composition
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional sulfonium salt-type photoacid generators in resist compositions fail to adequately inhibit acid diffusion, leading to deteriorated lithographic performance such as contrast, mask fidelity, and pattern rectangularity, and are associated with pattern collapse during fine pattern formation.
Innovation Solution
A sulfonium salt with a specific structure, represented by the formula (1), is used as a photoacid generator, providing excellent solvent solubility, high sensitivity, and high contrast, and is blended with a chemically amplified resist composition to inhibit acid diffusion and prevent pattern collapse.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional sulfonium salt-type photoacid generators are used, then the resist composition can be manufactured with existing materials, but acid diffusion is not adequately inhibited leading to deteriorated lithographic performance
Solution Approach 1:
The patent modifies the molecular structure of the sulfonium salt by introducing specific substituents (such as fluorinated alkyl groups, adamantyl groups, or other bulky hydrophobic groups) to change the steric parameters and electronic properties of the photoacid generator. This structural parameter change reduces acid diffusion while maintaining manufacturability with modified chemical compositions
2Manufacturing precision
If the resist composition is designed for high resolution, then pattern rectangularity can be improved, but acid diffusion increases causing pattern collapse
Solution Approach 1:
The patent introduces a quar oucher component into the resist composition that acts as an intermediary substance to intercept and neutralize diffusing acid molecules. This mediator prevents acid from reaching and affecting adjacent pattern regions, thereby preventing pattern collapse while maintaining high resolution and rectangularity
3Productivity
If the exposure dose is increased, then sensitivity can be improved, but mask fidelity deteriorates due to increased acid diffusion
Solution Approach 1:
The patent converts the potentially harmful effect of high exposure dose (which generates excessive acid and causes diffusion) by introducing acid diffusion inhibitors and quenchers that selectively neutralize excess acid. This transforms the harmful over-exposure effect into a beneficial process where the qu oucher system actively manages acid concentration to maintain both sensitivity and mask fidelity
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 sulfonium salt-based resist composition achieves high contrast and sensitivity, with improved lithographic performance in terms of exposure latitude and line width roughness, effectively preventing pattern collapse and enhancing mask fidelity.
Implementation Method 1
a sulfonium salt composed of a triphenylsulfonium cation and a perfluoroalkanesulfonate anion is commonly used
Data Source
AI summary
The present invention is a sulfonium salt represented by the following formula (1),wherein “p” represents an integer of 1 to 3; R11 represents a hydrocarbyl group having 1 to 20 carbon atoms; Rf represents a fluorine atom or a fluorine-atom-containing C1 to C6 group selected from alkyl, alkoxy, and sulfide; “q” represents an integer of 1 to 4; RALU represents an acid-labile group; “r” represents an integer of 1 to 4; R12 represents a hydrocarbyl group having 1 to 20 carbon atoms; “s” represents an integer of 0 to 4; “t” represents an integer of 0 to 2; Rf and —O—RALU are bonded to adjacent carbon atoms; and X− represents a non-nucleophilic counterion having no polymerizable group. This provides a sulfonium salt used for a resist composition having excellent solvent solubility, high sensitivity and high contrast, and excellent lithographic performance such as exposure latitude and LWR; a resist composition containing the sulfonium salt as a photoacid generator; and a patterning process using the resist composition.