Colloidal Silica Polishing Composition with Surface Protrusions
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Solution Overview
Problem
Current polishing compositions using colloidal silica particles do not achieve a high enough polishing rate for semiconductor device materials, such as silicon wafers.
Innovation Solution
A polishing composition with colloidal silica particles having larger diameters with an average aspect ratio of at least 1.15, protrusions taller than 3.5 nm, and a broad particle size distribution, along with a high purity, is used to enhance polishing efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional colloidal silica particles are used as abrasive grains, then the polishing composition can be manufactured with standard particle characteristics, but the polishing rate remains insufficient for semiconductor device materials
Solution Approach 1:
The invention applies local quality by creating protrusions only on specific regions of the colloidal silica particle surfaces. These protrusions are concentrated on particles with larger diameters (greater than the volume average), creating localized abrasive features that enhance material removal while the overall particle distribution maintains surface control. This selective localization of abrasive features resolves the contradiction between high polishing rate and surface flatness.
Solution Approach 2:
The invention changes key parameters of the colloidal silica particles: (1) aspect ratio of particles with larger diameters is set to 1.05 or more to create elongated shapes with protrusions, (2) protrusion height is controlled to be 3 nm or more for effective abrasion, and (3) particle diameter distribution is optimized with standard deviation of 5 nm or more. These parameter changes enable higher polishing rates while maintaining manufacturing precision.
2Productivity
If colloidal silica particles with protrusions are used to improve polishing rate, then material removal speed increases, but particle uniformity and control become more difficult
Solution Approach 1:
The invention applies local quality by creating protrusions only on specific regions of the colloidal silica particle surfaces. These protrusions are concentrated on particles with larger diameters (greater than the volume average), creating localized abrasive features that enhance material removal while the overall particle distribution maintains surface control. This selective localization of abrasive features resolves the contradiction between high polishing rate and surface flatness.
Solution Approach 2:
The invention changes key parameters of the colloidal silica particles: (1) aspect ratio of particles with larger diameters is set to 1.05 or more to create elongated shapes with protrusions, (2) protrusion height is controlled to be 3 nm or more for effective abrasion, and (3) particle diameter distribution is optimized with standard deviation of 5 nm or more. These parameter changes enable higher polishing rates while maintaining 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 achieves a significantly higher polishing rate, exceeding 1400 Å/min, by utilizing colloidal silica particles with specific surface features and properties that improve the sharpness and effectiveness of the abrasive action.
Implementation Method 1
colloidal silica particles each having a surface with a plurality of protrusions... capable of realizing a higher polishing rate
Data Source
Figure 1~2(b)
AI summary
A polishing composition contains colloidal silica particles having protrusions on the surfaces thereof. The average of values respectively obtained by dividing the height of a protrusion on the surface of each particle belonging to the part of the colloidal silica particles that has larger particle diameters than the volume average particle diameter of the colloidal silica particles by the width of a base portion of the same protrusion is no less than 0.245. Preferably, the part of the colloidal silica particles that has larger particle diameter than the volume average particle diameter of the colloidal silica particles has an average aspect ratio of no less than 1.15. Preferably, the protrusions on the surfaces of particles belonging to the part of the colloidal silica particles that has larger particle diameters than the volume average particle diameter of the colloidal silica particles have an average height of no less than 3.5 nm.