Ionic Liquid Film for Substrate Pattern Collapse Prevention
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Solution Overview
Problem
Existing substrate processing methods face challenges in preventing pattern collapse during drying due to high surface tension of liquids used, which can cause adjacent patterns to overlap, especially when using isopropyl alcohol (IPA), and do not effectively manage static electricity or reduce water introduction.
Innovation Solution
A substrate processing method involving the formation of a film using an ionic liquid with a cation containing a hydrocarbon chain of six or more carbon atoms, where at least one hydrogen atom is substituted with a fluorine atom, reducing surface tension and preventing pattern collapse, and utilizing supercritical CO2 for drying, which allows for efficient removal of the ionic liquid without evaporation and static electricity discharge.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If isopropyl alcohol (IPA) is used as an anti-drying liquid, then the substrate can be processed, but high surface tension causes pattern collapse and adjacent patterns overlap
Solution Approach 1:
The patent changes the surface tension parameter of the anti-drying liquid by replacing conventional IPA with ionic liquids having specifically controlled surface tension values (30-70 mN/m). This parameter modification resolves the contradiction by enabling pattern retention while avoiding the harmful high surface tension effects of IPA.
Solution Approach 2:
The patent employs composite ionic liquid formulations combining specific cations (with hydrocarbon chains of 6-18 carbon atoms) and anions to achieve optimal surface tension properties. This composite material approach allows precise control over surface tension to prevent pattern collapse while maintaining processing effectiveness.
2Productivity
If conventional liquids are used for drying, then evaporation occurs, but this introduces water and causes condensation issues
Solution Approach 1:
The patent utilizes the phase transition properties of ionic liquids, which remain liquid at processing temperatures and can be removed through controlled evaporation or substitution with supercritical CO2. This phase transition approach enables efficient drying while minimizing water introduction and condensation problems associated with conventional volatile liquids.
Solution Approach 2:
The patent introduces supercritical CO2 as an intermediary substance to replace the ionic liquid anti-drying layer. This intermediary approach allows efficient removal of the ionic liquid without direct evaporation, thereby preventing water introduction and condensation while maintaining high drying efficiency.
3Ease of operation
If high surface tension liquids are used, then static electricity is generated, but this complicates the processing environment
Solution Approach 1:
The patent modifies the electrical properties parameter by selecting ionic liquids with specific surface tension ranges (30-70 mN/m) that inherently reduce static electricity generation. This parameter change resolves the contradiction by maintaining processing stability while eliminating the harmful static electricity effects of conventional high surface tension liquids.
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 method effectively prevents pattern collapse by reducing surface tension, minimizes water introduction, and addresses static electricity issues, ensuring accurate pattern retention and efficient drying without evaporation or condensation.
Implementation Method 1
forming a film of an ionic liquid on a surface of a substrate... the ionic liquid has a cation containing a hydrocarbon chain having six or more carbon atoms, and at least one hydrogen atom in the hydrocarbon chain is substituted with a fluorine atom... effectively prevents pattern collapse by reducing surface tension
Implementation Method 2
utilizing supercritical CO2 for drying, which allows for efficient removal of the ionic liquid without evaporation
Data Source
AI summary
A substrate processing method includes forming a film of an ionic liquid on a surface of a substrate, on which a pattern is formed, by supplying the ionic liquid to the surface of the substrate, wherein the ionic liquid has a cation containing a hydrocarbon chain having six or more carbon atoms, and wherein at least one hydrogen atom in the hydrocarbon chain is substituted with a fluorine atom.