Colloidal Silica Production for High-Rate, Low-Defect Polishing
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Solution Overview
Problem
Existing methods for producing colloidal silica with high particle density and aggregation ratio are costly, time-consuming, and result in defects on polished substrates, and do not achieve optimal abrasiveness.
Innovation Solution
A production method for colloidal silica involving steps to prepare a mother liquor with an alkaline catalyst, adding alkoxysilane, and then an alkaline catalyst to form seed particles, followed by adding water and an organic solvent, results in silica particles with a primary particle size of 33 nm or more, an aggregation ratio of 1.2 or more, and a particle density of 1.95 or more, containing alkoxy groups and primary amines, with less than 15% of particles under 20 nm, enhancing abrasiveness and reducing production costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the production method in PTL 1 is used to produce colloidal silica with high particle density, then the particle density is improved, but the production time increases and the process becomes complicated and costly
Solution Approach 1:
The invention performs preliminary hydrolysis of alkoxysilane to form silicic acid before adding it to the mother liquor, rather than adding alkoxysilane directly. This preliminary action allows for better control of particle formation kinetics, achieving high particle density in a shorter time and with simpler process steps
Solution Approach 2:
The invention changes the concentration parameters by using a specific range of silicic acid concentration (5-50 mass%) and controlling the addition rate and reaction conditions. This parameter optimization enables achieving high particle density (1.95 or more) while reducing production time and simplifying the process
2Quantity of substance
If the production method in PTL 1 is used to produce colloidal silica with high particle density, then the particle density is improved, but the production cost increases and the process becomes complicated
Solution Approach 1:
By performing preliminary hydrolysis to prepare silicic acid solution, the invention simplifies the overall process flow and reduces the number of steps required. This preliminary preparation allows for more efficient use of materials and lower production costs while maintaining high particle density
Solution Approach 2:
The invention optimizes material parameters by using specific concentrations of silicic acid (5-50 mass%) and controlling the addition rate. This optimization reduces material waste, improves production efficiency, and lowers overall production costs while achieving the desired high particle density
3Quantity of substance
If the production method in PTL 1 is used to produce colloidal silica with high particle density, then the particle density is improved, but defects such as scratches on the substrate surface increase
Solution Approach 1:
The invention changes the particle size parameters by controlling the hydrolysis conditions and silicic acid concentration to achieve an optimal average primary particle size. This parameter control ensures high particle density while preventing particles that are too small from causing surface defects during polishing
Solution Approach 2:
The preliminary hydrolysis step allows for better control over particle formation, ensuring that particles reach the optimal size distribution before being added to the mother liquor. This prevents the formation of defective particles that would cause scratches on polished surfaces
4Ease of manufacture
If the production method in PTL 2 is used to produce colloidal silica, then the production process is simplified, but the aggregation ratio and particle density remain insufficient
Solution Approach 1:
The invention performs preliminary hydrolysis of alkoxysilane to form silicic acid before addition to the mother liquor. This preliminary action creates conditions that promote proper aggregation, achieving high aggregation ratio (1.2 or more) while maintaining process simplicity
Solution Approach 2:
The invention optimizes parameters including silicic acid concentration (5-50 mass%), addition rate, and reaction conditions to achieve proper aggregation. This parameter control enables simultaneous attainment of high aggregation ratio and simplified production process
5Ease of manufacture
If the production method in PTL 2 is used to produce colloidal silica, then the production process is simplified, but the abrasiveness of the colloidal silica is insufficient
Solution Approach 1:
The invention changes critical parameters including average primary particle size (33 nm or more), aggregation ratio (1.2 or more), and particle density (1.95 or more). These parameter optimizations simultaneously achieve high abrasiveness and simplified production process
Solution Approach 2:
The preliminary hydrolysis step ensures that silicic acid is properly prepared before addition, creating optimal conditions for forming particles with high abrasiveness. This preliminary preparation maintains process simplicity while achieving the desired particle characteristics for high abrasiveness
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 method produces colloidal silica with high polishing rate and low defectiveness, achieving high abrasiveness while simplifying the production process and reducing costs.
Implementation Method 1
a hydrolyzed solution obtained by hydrolyzing an alkoxysilane is added to a mother liquor
Implementation Method 2
silica particles containing alkoxy groups... produced by adding an alkoxysilane to a mother liquor containing an alkaline catalyst
Implementation Method 3
a mother liquor containing an alkaline catalyst... adding an alkoxysilane to a mother liquor containing an alkaline catalyst
Data Source
AI summary
A colloidal silica is disclosed that contains, with high purity, silica particles having an appropriate particle density, a high aggregation ratio, and a high alkoxy group content, and to provide a method for producing the colloidal silica in a simple manner at reduced costs. The colloidal silica containing silica particles is disclosed, wherein the silica particles have an average primary particle size of 33 nm or more, an aggregation ratio of 1.2 or more, and a particle density of 1.95 or more, the silica particles contain 1000 ppm by mass or more of alkoxy groups per gram of the silica particles, the proportion of the number of silica particles having an equivalent circle diameter under 20 nm is less than 15%, and the silica particles contain a primary amine in an amount of 5 μmol or more per gram of the silica particles.