Upper Layer Film Composition for Lithography Water Mark Prevention
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Solution Overview
Problem
Conventional upper layer films used in liquid immersion exposure for finer lithography fail to maintain a stable state and prevent defects such as water mark defects and inferior pattern defects due to insufficient receded contact angle, especially at high scan speeds.
Innovation Solution
A composition for forming an upper layer film comprising specific resins with particular repeating units, which provides sufficient transmission for exposure rays, is insoluble in water, and maintains a high receded contact angle, preventing defects even at high scan speeds.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional upper layer films are used in liquid immersion exposure, then the photoresist film is protected from water penetration, but the films fail to maintain stable film state and cause water mark defects and inferior pattern defects due to insufficient receded contact angle
Solution Approach 1:
The patent changes the chemical composition parameters of the upper layer film by incorporating specific fluorinated compounds (compounds of formula (1) and (2)) to achieve a receded contact angle of 70° or more. This parameter change in surface chemistry resolves the contradiction by maintaining film stability while preventing water mark defects through high water repellency.
Solution Approach 2:
The patent uses composite material formulation combining fluorinated compounds with specific functional groups (sulfonic acid groups, carboxylic acid groups, or phosphoric acid groups) to create an upper layer film that simultaneously achieves chemical stability in water and high surface hydrophobicity. This composite approach resolves the contradiction between film stability and defect prevention.
2Object-affected harmful factors
If the receded contact angle of upper layer film is increased to prevent water mark defects, then water repellency is improved, but the film may lose transmission properties for exposure rays
Solution Approach 1:
The patent applies local quality by concentrating fluorinated compounds with high water repellency at the film surface (achieving 70°+ receded contact angle) while maintaining the bulk film composition transparent to exposure rays. This localized functional differentiation resolves the contradiction between water repellency and optical transmission.
Solution Approach 2:
The patent carefully controls the concentration parameters of fluorinated compounds (0.1-10 mass%) and molecular weight (1,000-100,000) to optimize the balance between surface hydrophobicity and optical transparency. These parameter adjustments resolve the contradiction by achieving high receded contact angle without compromising exposure ray transmission.
3Productivity
If high scan speed is used in liquid immersion exposure, then productivity is improved, but liquid droplets remain on the photoresist film due to insufficient receded contact angle causing water mark defects
Solution Approach 1:
The patent applies preliminary action by pre-forming an upper layer film with high receded contact angle (70° or more) before the liquid immersion exposure process. This preliminary surface preparation ensures that even at high scan speeds, liquid droplets do not adhere to the photoresist film, thus maintaining pattern quality while enabling high productivity.
4Reliability
If the upper layer film is made highly insoluble in water to maintain stable film state, then film stability is improved, but the film becomes difficult to remove after exposure
Solution Approach 1:
The patent applies dynamics by designing an upper layer film with conditional solubility: highly insoluble in water during exposure (maintaining stability) but soluble in alkaline developing solutions (enabling easy removal). This dynamic responsiveness to different chemical environments resolves the contradiction between film stability and ease of removal.
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 suppresses water mark defects and inferior pattern defects by ensuring a stable film state and high receded contact angle, enabling high-resolution pattern formation at both ordinary and high scan speeds.
Implementation Method 1
the composition for formation of upper layer film, which is used for forming an upper layer film on the surface of a photoresist film and which comprises a resin (A) having a repeating unit represented by general formula (1-1) and not having a repeating unit represented by general formula (1-2), and a resin (B) having a repeating unit represented by general formula (1-2) and not having a repeating unit represented by general formula (1-1)... when the composition for formation of upper layer film is coated on the surface of a photoresist film and then subjected to preliminary baking at 50 to 150° C. for 1 to 360 seconds to form an upper layer film, a receded contact angle θ of 70° or more to water is given
Implementation Method 2
it has sufficient transmission for the wavelength of the radiation used... which, in liquid immersion exposure, is highly insoluble in a liquid medium (e.g. water) and can maintain a stable film state, and which has a sufficiently high receded contact angle and enables formation of a resist pattern of high resolution
Data Source
AI summary
A composition for formation of upper layer film, which is used for forming an upper layer film on the surface of a photoresist film and which comprisesa resin (A) having a repeating unit represented by the following general formula (1-1) and not having a repeating unit represented by the following general formula (1-2), anda resin (B) having a repeating unit represented by the following general formula (1-2) and not having a repeating unit represented by the following general formula (1-1).[In the general formulas (1-1) and (1-2), R1 is hydrogen or the like; R2 is single bonds or the like; and R3 is a fluorine-substituted, linear or branched alkyl group having 1 to 12 carbon atoms, or the like.] The composition can form an upper layer film giving a sufficiently high receded contact angle.