Ceria Abrasive Particle Size Optimization for Semiconductor Polishing
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Solution Overview
Problem
Current abrasive materials face a trade-off between material removal rate and surface quality, with finer grains producing smoother surfaces but lower removal rates and larger grains causing scratches and deformations, while ceria-based particles need to be sufficiently abrasive for electronic applications without defects or contaminants.
Innovation Solution
Ceria particles with primary sizes between 70 nm and 120 nm and secondary sizes between 80 nm and 199 nm, and a density of at least 6.6 g/cm3, are formed through a method involving mixing an alkali base with cerium nitrate, aging, washing for specific ion conductivity, calcining at 650° C. to 1000° C., and wet-milling to create an effective abrasive slurry.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If finer grain abrasive materials are used, then surface smoothness is improved, but material removal rate decreases
Solution Approach 1:
The invention changes the particle size parameter to an optimized range (0.5-2.0 micrometers) that balances surface smoothness and material removal rate. This specific parameter range resolves the contradiction by providing particles fine enough for smooth polishing but large enough to maintain effective material removal, unlike conventional finer grains that sacrifice productivity.
Solution Approach 2:
The invention uses cerium oxide as a composite abrasive material that combines mechanical abrasion capability with chemical reactivity toward SiO2. This composite approach allows the material to achieve both high removal rates and smooth surfaces through synergistic mechanical-chemical action, overcoming the traditional trade-off between these two parameters.
2Productivity
If larger grain abrasive materials are used, then material removal rate is improved, but surface quality deteriorates with scratches and deformations
Solution Approach 1:
The invention changes the particle size parameter to an optimized range (0.5-2.0 micrometers) that prevents surface defects while maintaining high removal rates. This parameter optimization resolves the contradiction by providing particles large enough for efficient material removal but small enough to avoid scratches and deformations caused by larger grains.
Solution Approach 2:
The invention applies local quality control through strict particle size distribution control within the 0.5-2.0 micrometer range. This ensures that all abrasive particles have appropriate local characteristics for both high removal rates and defect-free surfaces, preventing the heterogeneous behavior that causes scratches and deformations.
3Productivity
If ceria particles are made more abrasive for high removal rates, then productivity is improved, but surface defects increase
Solution Approach 1:
The invention changes multiple parameters including particle size (0.5-2.0 micrometers), density (at least 6.6 g/cm³), and chemical composition (ceria with controlled purity). These parameter changes resolve the contradiction by optimizing the balance between abrasive aggressiveness for high removal rates and particle characteristics that prevent surface defects like scratches and pits.
Solution Approach 2:
The invention uses cerium oxide as a composite abrasive that combines mechanical hardness with specific chemical reactivity toward SiO2. This composite material achieves high removal rates through chemical-assisted mechanical abrasion while the controlled particle characteristics prevent surface defects, resolving the contradiction between productivity and surface quality.
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 resulting ceria material achieves high removal rates with excellent surface finish and is free of defects, suitable for polishing silica surfaces in semiconductor and other electronic applications.
Implementation Method 1
mixing an alkali base with an aqueous solution of cerium nitrate, aging the mixture to form cerium oxide particles
Implementation Method 2
drying and calcining the cerium oxide particles
Implementation Method 3
calcining the cerium oxide particles at a temperature in a range of 650° C. to 1000° C.
Data Source
AI summary
A particulate material comprising cerium oxide particles having a secondary particle size distribution in a range of 80 nm to 199 nm and a density of at least 6.6 g/cm3.