Immersion Lithography Upper Layer Film Composition
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Solution Overview
Problem
In liquid immersion lithography, existing upper layer films fail to prevent water permeation, leading to resolution defects and lens contamination, as they are not sufficiently transparent to short wavelengths and tend to intermix with photoresist films, causing watermark and dissolution residue defects.
Innovation Solution
A composition for forming an upper layer film comprising a resin component with specific repeating units, including those represented by formulas (1-1) to (4), which forms a film with a receding contact angle of less than 60° or greater than 65°, preventing water permeation and intermixing while maintaining solubility in alkaline developers, thereby suppressing defects and ensuring high resolution patterns.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If an upper layer film is formed to prevent water permeation, then resolution is improved and lens contamination is prevented, but the film must be sufficiently transparent to short wavelengths which conflicts with water repellency requirements
Solution Approach 1:
The patent changes the chemical composition parameters of the upper layer film by incorporating specific repeating units with carboxyl groups and hydrophobic side chains. This compositional parameter change enables the film to achieve both water repellency (contact angle ≥ 60°) and sufficient transparency to 193nm radiation, resolving the contradiction between water protection and resolution maintenance.
Solution Approach 2:
The patent creates a composite upper layer film material combining hydrophobic segments (for water repellency) and transparent segments with specific repeating units (for optical clarity at 193nm). This composite structure allows the film to simultaneously prevent water permeation while maintaining the transparency needed for high-resolution lithography.
2Object-affected harmful factors
If the upper layer film has strong water repellency to prevent watermark defects, then water drops are prevented from remaining on the film, but dissolution residue defects increase due to insufficient water permeation control
Solution Approach 1:
The patent applies local quality by creating specific molecular regions within the polymer chain - hydrophobic side chains localized at the water interface for water repellency, and carboxyl-containing repeating units localized to control dissolution behavior. This spatial differentiation of functional groups within the same material enables simultaneous prevention of both watermark and dissolution residue defects.
3Stability of the object's composition
If the upper layer film prevents intermixing with photoresist to maintain stability, then film stability is improved, but the film must be easily dissolved in alkaline developers which conflicts with stability requirements
Solution Approach 1:
The patent introduces dynamic behavior through pH-responsive carboxyl groups that remain protonated and stable during exposure and development, then deprotonate in the alkaline developer to enable dissolution. This dynamic chemical behavior allows the film to exhibit stability under exposure conditions while being easily removable during development, resolving the contradiction between stability and ease of manufacture.
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 composition effectively protects photoresist films from water permeation, prevents lens contamination, and enhances resolution by maintaining film stability and transparency, reducing defects such as watermark and dissolution residue issues during liquid immersion lithography.
Implementation Method 1
The upper layer film must... maintain a stable covering effect without eluting components into a medium such as water used during liquid immersion lithography
Implementation Method 2
The upper layer film commonly used in liquid immersion lithography is provided with water repellency to suppress a watermark defect
Implementation Method 3
The upper layer film must exhibit sufficient transparency to the wavelength of radiation... When water is used as the medium in an ArF process, the resolution R is 69.4% (R=k1·(λ/1.44)/NA)
Implementation Method 4
must be easily dissolved in an alkaline solution or the like as a developer
Data Source
AI summary
A composition for forming an upper layer film includes a solvent and a resin component including a first resin having a first repeating unit and a second repeating unit. The first repeating unit is a repeating unit represented by a formula (1-1), a repeating unit represented by a formula (1-2), a repeating unit represented by a formula (1-3), or a combination thereof. The second repeating unit is a repeating unit represented by a formula (2-1), a repeating unit represented by a formula (2-2), or both thereof. The composition is to be used for forming the upper layer film in liquid immersion lithography.