EUV Photomask Resist Removal Liquid Composition
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Solution Overview
Problem
Current methods for EUV lithography lack effective resist removal techniques that do not damage the photomask's metal layers, particularly the absorbing and protective layers, which are critical for maintaining reflectivity and energy uniformity during exposure.
Innovation Solution
A resist removal method using a liquid composition containing an alkali compound, a specific nitrogen-containing compound with primary, secondary, tertiary, or quaternary amine structures, and water, where the water content is over 50% by mass, effectively removes the resist without damaging the photomask layers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional resist removal methods are used, then resist can be removed, but the photomask's metal layers (absorbing and protective layers) are damaged
Solution Approach 1:
The patent changes the chemical parameters of the resist removal liquid by specifying precise compositions: alkali compounds at 0.1-10% by mass, nitrogen-containing compounds at 0.01-5% by mass, and water content above 50% by mass. This controlled parameter change enables effective resist removal while preventing damage to the photomask's metal layers, resolving the contradiction between removal effectiveness and layer integrity.
2Productivity
If strong alkali solutions are used for resist removal, then resist removal performance is improved, but damage to the photomask substrate and metal layers increases
Solution Approach 1:
The patent creates a composite resist removal liquid system combining multiple components with specific functions: alkali compounds for primary resist dissolution, nitrogen-containing compounds for enhanced removal performance and substrate protection, and water as the base medium. This composite formulation achieves high removal efficiency while minimizing harmful effects on the photomask substrate through synergistic interactions between components.
Solution Approach 2:
The nitrogen-containing compounds act as intermediaries that mediate between the strong alkali environment and the photomask substrate. These compounds enable effective resist removal while protecting the substrate from direct exposure to harsh conditions, thus resolving the contradiction between removal efficiency and substrate protection.
3Reliability
If existing resist removal liquids are used, then removal process is simple, but removal performance on EUV photomask resist is insufficient
Solution Approach 1:
The patent establishes specific concentration parameters for each component (alkali compounds: 0.1-10%, nitrogen-containing compounds: 0.01-5%, water: >50%) to optimize removal performance. These controlled parameter changes ensure complete resist removal while maintaining manageable liquid composition complexity through well-defined ranges.
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 enables high-quality photomask production for EUV lithography by ensuring efficient resist removal while protecting the absorbing and protective layers, maintaining the photomask's integrity and performance.
Implementation Method 1
removing a resist provided on a photomask substrate by bringing a resist removing liquid into contact with the resist
Implementation Method 2
the resist removing liquid contains an alkali compound, a specific nitrogen-containing compound, and water
Data Source
AI summary
A resist removal method includes removing a resist provided on a photomask substrate by bringing a resist removing liquid into contact with the resist in patterning of a photomask for EUV lithography in which the resist removing liquid contains an alkali compound, a specific nitrogen-containing compound, and water, and a content of the water is more than 50% by mass.