Acid Generating Agents for ArF Immersion Lithography
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Solution Overview
Problem
Current acid generating agents used in chemically amplified resist compositions for semiconductor processes face challenges in achieving high resolution and reduced line edge roughness, while also minimizing water elution during ArF immersion lithography.
Innovation Solution
Development of novel acid generating agents represented by specific formulas (1) and (2), which include unsubstituted or substituted alkyl groups and perfluoroalkyl groups, along with organic counterions, to enhance diffusion rate control and hydrophobic characteristics, thereby reducing water elution and improving resist properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional acid generating agents are used, then the resist composition can be processed, but the resolution is insufficient and line edge roughness is high
Solution Approach 1:
The patent modifies the chemical structure of acid generating agents by changing parameters such as introducing bulky alicyclic rings, alkyl groups, alkoxy groups, or ether groups with large numbers of carbon atoms into the salt structure. These structural parameter changes are designed to control the diffusion rate of generated acid and improve transparency, thereby achieving better resolution and reduced line edge roughness in ArF immersion lithography processes
Solution Approach 2:
The patent develops composite acid generating agents that combine specific cation and anion moieties with tailored structural characteristics. The composite structure integrates hydrophobic groups and bulky cyclic structures to simultaneously achieve fast response time, controlled acid diffusion, and reduced water elution, resolving the contradiction between resolution and line edge roughness
2Speed
If acid generating agents with faster response time are developed, then the photo-acid generation efficiency is improved, but the diffusion rate of acid increases causing poor resolution
Solution Approach 1:
The patent changes the structural parameters of the acid generating agent by introducing bulky groups (alicyclic rings, long alkyl chains, alkoxy groups) that selectively slow down the diffusion rate of the generated acid while maintaining fast photo-acid generation response. This parameter optimization resolves the contradiction between response speed and resolution by decoupling the generation speed from the diffusion rate through molecular structure design
3Stability of the object's composition
If photo-acid generating agents are modified to reduce water elution, then the resist composition stability is improved, but the diffusion rate of acid decreases affecting pattern formation
Solution Approach 1:
The patent optimizes the hydrophobicity parameter of the acid generating agent by introducing hydrophobic groups (alkyl groups, alicyclic rings) that reduce water elution and improve composition stability. Simultaneously, the patent adjusts the molecular size and structure to maintain appropriate acid diffusion rates, resolving the contradiction between stability and diffusion speed through multi-parameter optimization
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 new acid generating agents demonstrate improved resolution, reduced line edge roughness, and minimized water elution, effectively addressing the limitations of existing agents in ArF immersion lithography.
Implementation Method 1
non-ionic photo-acid generating agents were developed, so that such an agent would generate a sulfonic acid derivative such as toluenesulfonic acid, when irradiated with light
Implementation Method 2
the anion moiety has substantially greater influence than the cation moiety on the physical and chemical characteristics which can improve the fluidity of acid
Data Source
AI summary
An acid generating agent represented by the following formula (1) or (2) is provided, which is included in chemically amplified resist compositions:wherein in the formula (1) and (2), X represents an unsubstituted or substituted alkyl group having 1 to 20 carbon atoms and selected from alkyl, haloalkyl and alkylsulfonyl, which may have at least one hydrogen atom substituted by an ether group, an ester group, a carbonyl group, an acetal group, a nitrile group, a cyano group, a hydroxyl group, a carboxyl group or an aldehyde group, or represents a perfluoroalkyl group having 1 to 4 carbon atoms; R6 represents an alkyl group having 1 to 10 carbon atoms, an alkoxy group having 1 to 10 carbon atoms, or a heteroatom selected from nitrogen, sulfur, fluorine and oxygen; m is an integer from 0 to 2; and A+ is an organic counterion.