Pre-Wetting Solvent Mixtures for Uniform Thin Resist Films
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Solution Overview
Problem
Existing methods struggle to form a uniform and thinner resist film with excellent defect inhibition performance using a small amount of resist composition, often resulting in uneven film thickness and insufficient defect prevention.
Innovation Solution
A chemical liquid comprising a mixture of two or more organic solvents, carefully selected from specific compounds, with controlled ether-based compound content and vapor pressure, surface tension, and Hansen solubility parameters, is used for pre-wetting the substrate before applying the resist composition.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a prewet agent containing a single organic solvent is used, then the coating process is simple, but uniform film formation and defect inhibition become insufficient
Solution Approach 1:
The patent applies composite materials by formulating the prewet agent as a mixture of multiple organic solvents (e.g., cyclohexanone, γ-butyrolactone, ethyl lactate, butyl acetate) rather than using a single solvent. This composite solvent system provides synergistic effects that improve film uniformity and defect inhibition while maintaining process simplicity. Each solvent contributes different properties that collectively achieve the desired coating quality.
Solution Approach 2:
The patent applies parameter changes by carefully controlling the composition ratios, vapor pressure ranges (160-1000 Pa at 25°C), and Hansen solubility parameters of the organic solvent mixture. By adjusting these parameters, the prewet agent achieves optimal wetting properties and evaporation characteristics that enable uniform thin film formation and effective defect prevention.
2Device complexity
If a prewet agent containing a single organic solvent is used, then the formulation is simple, but defect inhibition performance becomes insufficient
Solution Approach 1:
The patent uses composite materials by combining multiple organic solvents with complementary defect-inhibiting properties. The mixture of solvents creates a more effective barrier against coating defects compared to single solvents, while the formulation remains relatively simple with just 2-5 carefully selected components.
Solution Approach 2:
The patent applies parameter changes by selecting solvents with specific vapor pressure ranges and Hansen solubility parameters that optimize defect inhibition. The controlled evaporation rate and solubility characteristics of the solvent mixture prevent common coating defects while keeping the formulation straightforward.
3Quantity of substance
If a small amount of resist composition is used, then material usage is efficient, but achieving uniform thickness becomes difficult
Solution Approach 1:
The patent applies preliminary action by using the prewet agent to prepare the substrate surface before applying the resist composition. The prewet agent creates an optimized surface condition that enhances resist composition spreading and uniformity, allowing achieving uniform thin films even with small amounts of resist material.
Solution Approach 2:
The patent applies parameter changes by controlling the vapor pressure and surface tension of the prewet agent to optimize resist composition deposition. The prewet agent's parameters are adjusted to ensure uniform distribution of the resist composition across the substrate, enabling uniform film formation with minimal material usage.
4Ease of manufacture
If the vapor pressure of the prewet agent is not controlled, then formulation is easier, but film formation uniformity and defect inhibition deteriorate
Solution Approach 1:
The patent applies parameter changes by controlling the vapor pressure of the prewet agent within the range of 160-1000 Pa at 25°C. This controlled vapor pressure ensures optimal evaporation rate during coating, preventing both premature drying and excessive spreading, thereby achieving uniform film formation while maintaining relatively easy formulation procedures.
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 solution enables the formation of a thinner resist film with uniform thickness and improved defect inhibition, enhancing resist saving properties and reducing defects in the pattern forming process.
Implementation Method 1
a chemical liquid comprising a mixture of two or more kinds of organic solvents... with controlled vapor pressure, surface tension, and Hansen solubility parameters, is used for pre-wetting substrates
Implementation Method 2
the chemical liquid contains or does not contain an ether-based compound... in a case where the chemical liquid contains the ether-based compound, a content of the ether-based compound in the chemical liquid is less than 10 mass ppm
Data Source
AI summary
An object of the present invention is to provide a chemical liquid which makes it possible to form a thinner resist film having a uniform thickness on a substrate by using a small amount of resist composition and demonstrates excellent defect inhibition performance. Another object of the present invention is to provide a pattern forming method. A chemical liquid of the present invention contains a mixture of two or more kinds of organic solvents, in which the organic solvents are selected from the group consisting of compounds represented by Formulae (1) to (7), compounds represented by Formulae (9) to (11), a 3- to 5-membered cyclic ketone compound that may have a substituent, a cyclic ketone compound with 6 or more members that may have a substituent, a lactone compound, and a lactam compound, the chemical liquid contains or does not contain an ether-based compound other than the compounds represented by Formula (1), Formula (5), Formula (7), and Formulae (9) to (11), and in a case where the chemical liquid contains the ether-based compound, a content of the ether-based compound in the chemical liquid is less than 10 mass ppm with respect to a total mass of the chemical liquid.