Chemically Amplified Negative Resist Composition for ArF Lithography
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Solution Overview
Problem
Chemically amplified negative resist compositions used in semiconductor and photomask processing face challenges in achieving reduced line edge roughness (LER) when patterned with ArF excimer laser, particularly due to acid diffusion issues.
Innovation Solution
A chemically amplified negative resist composition incorporating an onium salt with a fluorine atom or trifluoromethyl group, which effectively controls acid diffusion, comprising specific structural formulas that enhance resolution and reduce LER, along with a resin that becomes alkali insoluble and an acid generator, and optionally includes a crosslinking agent and basic compounds for improved patterning.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a phenol unit is used as the alkali soluble unit in the polymer, then the resist composition shows remarkable absorption in wavelength of near 200 nm, but it cannot be used as a resist composition for ArF excimer laser due to lack of light transmittance
Solution Approach 1:
The patent changes the chemical structure parameters of the polymer by replacing phenol units with naphthol units having different hydroxyl group positions (ortho, meta, para). This structural parameter change modifies the light absorption characteristics, enabling transmittance at ArF excimer laser wavelength (193 nm) while maintaining alkali solubility and other required properties for chemically amplified negative resist.
2Manufacturing precision
If an acid diffusion controlling agent is added to suppress acid diffusion, then resolution is improved, but line edge roughness (LER) increases
Solution Approach 1:
The patent modifies the chemical structure parameters of the acid diffusion controlling agent by introducing fluorine atoms at specific positions (α-position or fluoroalkyl groups). This structural modification changes the agent's properties to achieve both effective acid diffusion control (improving resolution) and reduced line edge roughness, overcoming the traditional trade-off between these two parameters.
Solution Approach 2:
The patent creates a composite acid diffusion controlling agent that combines fluorinated carboxylic acid structures with onium salt structures. This composite structure integrates the acid diffusion control function with additional properties that suppress line edge roughness, achieving both high resolution and smooth line edges simultaneously.
3Strength
If a strong acid photoacid generator is used, then chemically amplified negative resist shows good etching resistance, but acid diffusion distance increases causing resolution degradation
Solution Approach 1:
The patent introduces a fluorinated carboxylic acid onium salt as an intermediary substance between the strong acid photoacid generator and the polymer. This intermediary acts as a buffer that moderates acid diffusion while maintaining the etching resistance benefits of strong acid generation, thereby resolving the contradiction between etching resistance and resolution.
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 resolution and reduced LER, suitable for microprocessing technologies like electron beam and EUV lithography, by effectively controlling acid diffusion and promoting crosslinking reactions, leading to high-resolution patterns with minimal undercut and excellent adhesion.
Implementation Method 1
an acid generator which is decomposed by exposure light to generate an acid
Implementation Method 2
a basic compound to control diffusion of the acid generated by the exposure
Data Source
AI summary
The present invention provides the chemically amplified negative resist composition comprises an onium salt represented by the following general formula (0-1), a resin which becomes alkali insoluble by an action of an acid and an acid generator,wherein Rf represents a fluorine atom or a trifluoromethyl group; Y represents a cyclic hydrocarbon group having 3 to 30 carbon atoms, the hydrogen atom in the cyclic hydrocarbon group may be substituted by a hetero atom itself or a monovalent hydrocarbon group which may be substituted by a hetero atom(s), and the hetero atom(s) may be interposed into the cyclic structure of the cyclic hydrocarbon group and the monovalent hydrocarbon group; and M+ represents a monovalent cation. There can be provided a chemically amplified negative resist composition which can improve resolution at the time of forming a pattern and give a pattern with less line edge roughness (LER).