Onium Salt Resist Composition for Lithography Acid Diffusion Control
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Solution Overview
Problem
Current chemically amplified resist compositions fail to fully suppress acid diffusion during photolithography, leading to degraded lithography performance in terms of contrast, mask error factor, and line width roughness, especially when using high-energy radiation sources like KrF or ArF excimer lasers.
Innovation Solution
A chemically amplified resist composition incorporating a specific onium salt with a lactone structure as a photoacid generator, which reduces acid diffusion and enhances sensitivity, contrast, and mask error factor, and line width roughness by incorporating an acid labile group and a linker with at least two carbon atoms, thereby improving exposure latitude and pattern fidelity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional photoacid generators are used in chemically amplified resist compositions, then the resist can achieve adequate sensitivity, but acid diffusion occurs during photolithography which degrades lithography performance including contrast, mask error factor, and line width roughness
Solution Approach 1:
The patent modifies the molecular structure of the photoacid generator by incorporating a lactone structure with specific parameters: a carbonyl group at position 2, fluorine atoms at positions 3 and 4, and a counterion with specific fluorinated alkyl groups. These parameter changes in the molecular structure reduce acid diffusion while maintaining sensitivity, directly resolving the contradiction between lithography performance and acid diffusion control
Solution Approach 2:
The patent creates a composite photoacid generator structure combining multiple functional groups: the lactone ring structure, fluorinated substituents, and specific counterions. This composite molecular design achieves both high sensitivity and reduced acid diffusion by integrating multiple chemical features that work synergistically to control acid behavior during lithography
2Productivity
If the resist composition is designed for high sensitivity, then exposure dose can be reduced, but acid diffusion increases which degrades pattern fidelity and line width control
Solution Approach 1:
The patent changes the chemical parameters of the photoacid generator by introducing a lactone structure with specific fluorine substitution patterns and counterion composition. These parameter modifications enable the material to achieve high sensitivity (lower exposure dose requirement) while simultaneously suppressing acid diffusion, thus improving both productivity and manufacturing precision
3Object-generated harmful factors
If fluorinated alkane sulfonic acids are used as photoacid generators, then acid diffusion is reduced, but the molecular design flexibility is limited and environmental safety concerns arise due to non-degradability
Solution Approach 1:
The patent develops a composite molecular structure combining the beneficial fluorinated lactone core with versatile substituent options. The base structure provides acid diffusion control, while the modular substituent groups (R1-R6) allow for molecular design flexibility and environmental considerations, resolving the contradiction between diffusion control and design adaptability
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 improved lithography performance with reduced acid diffusion, higher sensitivity, and better pattern fidelity, enabling precise micropatterning with enhanced exposure latitude and mask error factor control.
Implementation Method 1
a chemically amplified resist composition comprising a photoacid generator, wherein the photoacid generator is the onium salt having the formula (1)
Implementation Method 2
RAL is an acid labile group
Data Source
AI summary
A novel onium salt of formula (1) and a chemically amplified resist composition comprising the same as a PAG are provided. When processed by photolithography using KrF or ArF excimer laser, EB or EUV, the resist composition has a high sensitivity and reduced acid diffusion and is improved in exposure latitude, MEF, and LWR.