Positive Resist Composition for ArF Lithography Resolution
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Solution Overview
Problem
Current resist materials for ArF excimer laser lithography face challenges such as reduced resolution due to acid diffusion, decreased etch resistance with thin films, and lowered sensitivity with high-accelerating-voltage electron beam exposure, which hinder the production of finer feature sizes and higher resolution in LSI devices and mask processing.
Innovation Solution
A positive resist composition comprising specific polymer repeat units with acid labile groups that enhance sensitivity and resolution, allowing for controlled acid migration and improved etch resistance, is developed. This composition includes polymers with aromatic hydrocarbon groups and acid labile groups that facilitate high-reactivity deprotection reactions at lower temperatures, along with a chemically amplified resist formulation including a photoacid generator and basic compound.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the thickness of resist film is reduced to achieve higher resolution, then resolution is improved, but etch resistance deteriorates
Solution Approach 1:
The patent introduces a novel polymer repeat unit structure with specific aromatic hydrocarbon groups and acid-labile protective groups that changes the chemical parameters of the resist material. This structural modification enables the resist to maintain high etch resistance even at reduced film thicknesses of 50 nm or less, while achieving improved resolution through controlled acid migration during post-exposure bake
Solution Approach 2:
The patent creates a composite resist composition by combining the newly synthesized polymer repeat units with specific photoacid generators and basic compounds. This composite formulation achieves synergistic effects where the polymer structure provides both the necessary etch resistance and controlled acid migration properties, enabling simultaneous improvement in resolution and maintenance of etch resistance
2Productivity
If acid migration is increased to promote deprotection reaction, then sensitivity is improved, but resolution deteriorates
Solution Approach 1:
The patent modifies the physical and chemical parameters of the resist system by introducing a novel polymer structure with specific repeat units containing aromatic hydrocarbon groups and acid-labile protective groups. This structural change enables controlled acid migration that promotes deprotection reactions for high sensitivity while maintaining resolution through the specific molecular architecture that limits excessive acid diffusion
Solution Approach 2:
The patent uses a photoacid generator as an intermediary substance that mediates between the incident light and the polymer repeat units. The photoacid generator produces acid upon exposure that triggers the deprotection reaction, enabling sensitivity improvement while the controlled release mechanism maintains resolution by limiting uncontrolled acid migration
3Manufacturing precision
If the accelerating voltage of electron beam is increased to improve resolution, then resolution is improved, but sensitivity deteriorates
Solution Approach 1:
The patent changes the chemical composition parameters of the resist material by introducing novel polymer repeat units with specific aromatic hydrocarbon groups and acid-labile protective groups. This compositional change enables the resist to maintain high sensitivity even under high-accelerating-voltage electron beam exposure conditions, while achieving improved resolution through the controlled acid migration characteristics of the new polymer structure
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 resist composition achieves high resolution and sensitivity, enabling precise micropatterning and improved etch resistance, suitable for both ArF excimer laser lithography and high-accelerating-voltage electron beam exposure, thus supporting the production of finer feature sizes and higher resolution in LSI devices and mask processing.
Implementation Method 1
the acid generated upon exposure triggers deprotection reaction on the base resin which proceeds during heat treatment following exposure
Implementation Method 2
Migration of the acid occurs during PEB. Since chemically amplified resist materials depend on the function of the acid to act as a catalyst to promote deprotection reaction, moderate acid migration is necessary
Implementation Method 3
lowered sensitivity with high-accelerating-voltage electron beam exposure
Data Source
AI summary
A positive resist composition comprises a polymer comprising repeat units having formula (1) or (2).Hereindenotes an aromatic hydrocarbon group, R1 is H, methyl or trifluoromethyl, R2 is H, C1-C12 alkyl or aromatic hydrocarbon group, R3 is C1-C12 alkyl, or R2 and R3 may bond together to form a ring, and a is 1 or 2. When used in the ArF lithography, the resist composition exhibits high resolution. When used in the EB image writing for mask processing, the resist composition exhibits high resolution and sensitivity sufficient to comply with high-accelerating-voltage EB irradiation, and high etch resistance.