Resist Lower-Layer Composition with Thermal Acid Generator for Lithography
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Solution Overview
Problem
Current multi-layer resist methods face challenges in achieving high anti-poisoning effects and environmental sustainability due to issues like acid volatility, amine contamination, and the use of harmful perfluorooctanesulfonic acids, which affect the precision and reliability of pattern formation in semiconductor manufacturing.
Innovation Solution
A resist lower-layer composition is developed that includes a thermal acid generator generating 2-(alkylcarbonyloxy)-1,1-difluoroethanesulfonic acid, which becomes insoluble in alkaline developers and effectively neutralizes amine contaminants, while being low in environmental impact and volatility, combined with a base resin and acid crosslinking agent for enhanced film formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional thermal acid generators are used in resist lower layer, then acid generation occurs during baking, but acid volatility causes loss of anti-poisoning effect and environmental harm
Solution Approach 1:
The patent changes the chemical structure of the thermal acid generator by introducing a carboxyl group that forms an intramolecular hydrogen bond with the sulfonic acid group. This structural modification reduces the volatility of the generated acid while maintaining its anti-poisoning effect, directly resolving the contradiction between reliability and substance loss.
Solution Approach 2:
The patent converts the potentially harmful volatile acid into a beneficial non-volatile acid by using the carboxyl-sulfonic acid hydrogen bonding system. The acid that would normally evaporate and cause environmental harm is now retained in the resist film, providing continuous anti-poisoning protection while eliminating the harmful volatility issue.
2Strength
If perfluorooctanesulfonic acid is used as thermal acid generator, then strong acid strength is achieved, but environmental harm increases due to persistence and bioaccumulation
Solution Approach 1:
The patent replaces the persistent, bioaccumulative perfluorooctanesulfonic acid with a shorter-chain sulfonic acid (3-6 carbon atoms) that is less environmentally harmful. The acid performs its function during the lithography process and then degrades, avoiding the long-term environmental persistence and bioaccumulation problems of perfluorooctanesulfonic acid.
Solution Approach 2:
The patent modifies the carbon chain length parameter of the sulfonic acid from 8 carbons (perfluorooctane) to 3-6 carbons, which significantly reduces environmental persistence and bioaccumulation potential while maintaining sufficient acid strength for the intended application in resist lower layer.
3Strength
If resist lower layer film contains silicon atoms for etching resistance, then etching resistance improves, but anti-reflection performance deteriorates due to increased reflectance
Solution Approach 1:
The patent applies local quality by concentrating silicon atoms specifically in the etching resistance layer rather than distributing them throughout the entire resist lower layer structure. This allows the silicon-containing layer to provide etching resistance while the overall structure maintains low reflectance properties through proper layer design and material selection.
Solution Approach 2:
The patent uses composite material structure combining silicon-containing compounds for etching resistance with other materials that provide low reflectance. The composite approach allows both functions to coexist: the silicon provides etching resistance while the overall composite structure maintains anti-reflection performance.
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 solution provides a high anti-poisoning effect, reduces adverse effects like footing, and enables precise pattern formation with reduced environmental load by maintaining acid strength and stability during the lithography process.
Implementation Method 1
a thermal acid generator for generating an acid represented by general formula (1) by heating at a temperature of 100° C. or higher
Implementation Method 2
effectively neutralizes amine contaminants, while being low in environmental impact and volatility
Implementation Method 3
combined with a base resin and acid crosslinking agent for enhanced film formation
Data Source
AI summary
A resist lower-layer composition configured to be used by a multi-layer resist method used in lithography to form a layer lower than a photoresist layer acting as a resist upper layer film. The resist lower-layer composition is insoluble or poorly-soluble in an alkaline developer after formation of the lower layer, and the resist lower-layer composition comprises, at least, a thermal acid generator for generating an acid by heating at a temperature of 100° C. or higher.