Polishing Liquid Composition for Wafer Haze Reduction
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Solution Overview
Problem
Current polishing liquid compositions for wafers fail to effectively improve haze during the final polishing stage, with existing solutions either worsening light point defects or providing uncertain haze improvement.
Innovation Solution
A polishing liquid composition comprising water, silica particles, an alkaline compound, polyvinyl alcohol, anion-modified polyvinyl alcohol, and a surfactant, with specific ratios and modifications to enhance hydrophilicity and dispersibility, improving the wafer's flatness and reducing haze.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If cellulose derivatives (hydroxyethyl cellulose) are used as water-soluble polymers in the polishing liquid composition, then the hydrophilicity of the wafer surface is improved and attachment of abrasive grains is prevented, but the quality fluctuates and light point defects worsen
Solution Approach 1:
The patent changes the chemical composition parameters by replacing cellulose derivatives with a specific water-soluble polymer (polyvinyl alcohol with 87-89 degree saponification and 100,000-300,000 molecular weight) that maintains the necessary hydrophilic properties while eliminating quality fluctuations and light point defect issues
Solution Approach 2:
The patent uses a synthetic polymer (polyvinyl alcohol) that is more stable and consistent in performance compared to natural cellulose derivatives, effectively replacing the less reliable natural material with a more dependable synthetic alternative
2Reliability
If synthetic water-soluble polymers (polyvinyl alcohol) are used in the polishing liquid composition, then quality fluctuation is eliminated, but haze improvement is insufficient
Solution Approach 1:
The patent optimizes specific parameters of the polyvinyl alcohol including saponification degree (87-89%) and molecular weight (100,000-300,000), and determines the optimal concentration range (0.03-0.15%) to achieve both quality stability and haze improvement
Solution Approach 2:
The patent creates a composite polishing liquid composition that combines polyvinyl alcohol with specific additives including surfactants (0.003-0.05% concentration) and alkaline compounds, where the synergistic interaction between components achieves both reliability and haze improvement
3Device complexity
If the polishing liquid composition uses conventional ingredients without optimized ratios, then the formulation is simple, but haze improvement is not achieved and flatness is insufficient
Solution Approach 1:
The patent specifies precise concentration ranges for each component: polyvinyl alcohol (0.03-0.15%), anion-modified polyvinyl alcohol (0.003-0.05%), surfactant (0.003-0.05%), creating an optimized formulation that achieves superior flatness (0.3 nm RMS or less) and haze improvement
Solution Approach 2:
The patent develops a multi-component composite polishing liquid containing water, silica particles (5-100 nm), alkaline compound, polyvinyl alcohol, anion-modified polyvinyl alcohol, and surfactant, where the synergistic interaction of components achieves both simplicity and high manufacturing precision
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 enhances hydrophilicity and improves haze by ensuring uniform contact of silica particles with the wafer surface, achieving better flatness and polishing performance.
Implementation Method 1
a water-soluble polymer compound having a stress relaxation function is effective not only in reducing damage caused by abrasive grains or foreign substances but also in providing the hydrophilicity to the wafer surface and preventing attachment of abrasive grains or foreign substances
Implementation Method 2
The polishing step is carried out by pressing the wafer as a target to be polished against a polishing pad and relatively moving the wafer while a polishing liquid composition is supplied onto the surface of the polishing pad
Implementation Method 3
a polishing liquid composition is generally used in which an alkaline compound is added and then a water-soluble polymer compound is added to silica particles dispersed in water
Data Source
AI summary
An object is to provide a polishing liquid composition that can provide hydrophilicity to a wafer surface and effectively improve a haze in polishing of wafers for substrates in electronics industry. The present invention is a polishing liquid composition for wafers, comprising: water; silica particles; an alkaline compound; a polyvinyl alcohol; an anion-modified polyvinyl alcohol; and a surfactant, wherein the mass ratio of the anion-modified polyvinyl alcohol to the polyvinyl alcohol is 0.6 to 5.5. The anion-modified polyvinyl alcohol is preferably a polyvinyl alcohol modified with a carboxy group or a sulfonic acid group.