Composite Thinner Composition for Edge Bead Removal
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Solution Overview
Problem
Conventional thinner compositions for photolithography processes have limited ability to dissolve various types of photosensitive materials, leading to poor edge bead removal and uniformity issues, especially with increasing integration density and wafer size, resulting in defects and non-uniform coatings.
Innovation Solution
A thinner composition comprising 50-90% propylene glycol monomethyl ether acetate, 1-20% propylene glycol monomethyl ether, 1-10% γ-butyrolactone, and 1-20% n-butyl acetate, with optional surfactants, is used for pre-wetting and edge bead removal, optimizing volatility, surface tension, and viscosity to enhance dissolving ability and uniformity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a commercial thinner composition is used, then it can dissolve a specific type of photoresist, but it lacks the ability to dissolve various types of photoresist with different chemical compositions
Solution Approach 1:
The patent employs a composite thinner composition containing four specific solvents (PGMEA, PGME, GBL, and nBA) in defined proportions. This composite formulation combines the dissolving capabilities of individual solvents to effectively dissolve diverse photoresist types with different chemical compositions, thereby achieving both versatility and reliable dissolving performance across multiple photoresist formulations.
Solution Approach 2:
The patent optimizes the concentration ratios of each solvent component within specific ranges (PGMEA: 50-90%, PGME: 1-20%, GBL: 1-10%, nBA: 1-20%) to balance dissolving ability, volatility, and coating uniformity. By adjusting these compositional parameters, the thinner achieves universal compatibility with various photoresist types while maintaining consistent dissolving performance.
2Area of stationary object
If the wafer is rinsed at a relatively slow speed to accommodate large diameter wafers, then it can handle larger wafers, but the thinner composition with poor dissolving rate cannot uniformly remove edge beads of photoresist
Solution Approach 1:
The multi-component solvent system provides enhanced and balanced dissolving kinetics that enable effective edge bead removal even at slow rinsing speeds required for large diameter wafers. The combination of solvents with different polarities and dissolving rates ensures uniform penetration and dissolution of photoresist edge beads across the entire wafer surface, maintaining manufacturing precision regardless of wafer size.
Solution Approach 2:
The optimized solvent composition ratios create a thinner with improved wetting properties and controlled evaporation rate, allowing sufficient contact time with edge beads at slow rinsing speeds. This parameter optimization ensures uniform dissolving action across large wafer surfaces without requiring high rinsing speeds that would compromise edge bead removal uniformity.
3Productivity
If the thinner composition has high volatility to evaporate quickly, then it can reduce processing time, but it may cause non-uniform coating and defects like cracks and tearing
Solution Approach 1:
The composite thinner formulation combines solvents with complementary volatility characteristics. PGMEA and PGME provide moderate volatility for reasonable processing speed, while GBL and nBA contribute to coating uniformity and defect suppression. This balanced volatility profile across multiple components enables both efficient processing and uniform coating without cracks or tearing.
Solution Approach 2:
The patent carefully controls the volatility parameters of individual solvent components within specific concentration ranges to achieve an optimal overall volatility balance. This parameter optimization ensures sufficiently fast evaporation for productivity while preventing excessive volatility that would cause coating non-uniformity, cracks, or tearing defects.
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 removes edge beads and defects, improves coating uniformity, and suppresses defects like cracks and tearing, while being safer and more stable for use in semiconductor fabrication.
Implementation Method 1
a thinner composition including about 50 to about 90% by weight of propylene glycol monomethyl ether acetate, about 1 to about 20% by weight of propylene glycol monomethyl ether, about 1 to about 10% by weight of γ-butyrolactone, and about 1 to about 20% by weight of n-butyl acetate
Data Source
AI summary
In a thinner composition and a method of forming a photosensitive film, the thinner composition includes about 50 to about 90% by weight of propylene glycol monomethyl ether acetate, about 1 to about 20% by weight of propylene glycol monomethyl ether, about 1 to about 10% by weight of γ-butyrolactone, and about 1 to about 20% by weight of n-butyl acetate. The thinner composition may have a proper volatility and an improved ability to dissolve various types of photosensitive materials, and thus the thinner composition may be usefully employed in an edge bead rinse process, a rework process or a pre-wetting process.