Resist Composition with Lactone Polymer for Immersion Lithography
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Solution Overview
Problem
ArF immersion lithography faces issues such as profile changes and 'blob defects' due to water penetration and sensitivity variations in resist films, particularly when using fluorinated protective coatings and hydrophobic compounds, which affect pattern formation and resolution in semiconductor manufacturing.
Innovation Solution
An alkali-soluble polymer with lactone units is introduced as an additive to resist compositions, reducing the contact angle of the resist film surface while maintaining a high water-barrier property, thereby minimizing profile changes and preventing water penetration during immersion lithography.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a fluorinated protective coating is applied to prevent water penetration, then water barrier property is improved, but profile changes occur due to acid dissolution in water
Solution Approach 1:
The patent introduces a specific polymer compound as an intermediary substance within the resist film that provides water barrier functionality without forming a separate protective coating layer. This polymer contains hydrophobic groups that repel water while being integrated into the resist matrix, thus preventing water penetration without causing profile changes from acid dissolution of external coatings.
Solution Approach 2:
The resist composition is formulated as a composite material containing the base resist polymer, photoacid generator, and specifically designed polymer compound with hydrophobic characteristics. This composite structure provides both the necessary photoresist functionality and water barrier properties within a single integrated film, eliminating the need for separate fluorinated protective coatings.
2Object-affected harmful factors
If hydrophobic compounds are added to resist material to prevent water penetration, then water barrier property is improved, but contact angle increases causing blob defects
Solution Approach 1:
The patent carefully controls the chemical structure and composition parameters of the polymer compound to achieve optimal hydrophobicity. By adjusting the type and amount of hydrophobic groups in the polymer, the contact angle is controlled to provide sufficient water barrier protection while remaining below the threshold that causes blob defects during development.
Solution Approach 2:
The polymer compound provides localized water barrier functionality within specific regions of the resist film structure. The hydrophobic groups are distributed throughout the resist matrix at controlled concentrations, creating local water-repelling zones that prevent penetration without forming excessive surface hydrophobicity that would cause blob defects.
3Device complexity
If alkali-soluble protective film is used to eliminate special stripping unit, then device complexity is reduced, but solvent for coating leaves room for improvement
Solution Approach 1:
The patent extracts the water barrier functionality from a separate protective coating layer and integrates it directly into the resist film composition itself. This eliminates the need for both the protective coating application step and the subsequent stripping step, while also avoiding the solvent issues associated with coating processes.
Solution Approach 2:
The resist film itself provides the water barrier protection through the incorporated polymer compound, making the resist material self-protecting against water penetration during immersion lithography. This self-service approach eliminates the need for external protective coatings and their associated coating solvents.
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 use of the alkali-soluble polymer with lactone units enhances the adaptability of resist films in both dry and immersion lithography, reducing 'blob defects and improving pattern formation by maintaining a high water-barrier property, thus enabling more reliable semiconductor manufacturing processes.
Implementation Method 1
reducing the contact angle of the resist film surface
Implementation Method 2
maintaining a high water-barrier property, thereby minimizing profile changes and preventing water penetration
Implementation Method 3
profile changes occur because the acid once generated from a photoacid generator and the basic compound added to the resist can be partially dissolved in water
Data Source
AI summary
To a resist composition, an alkali-soluble polymer having fluorinated ester-containing lactone units incorporated therein is included as an additive. The resist composition forms a resist film having a reduced contact angle after development. The resist film prevents water penetration during immersion lithography.