Mixed-Phase Ceria Dispersion for Low-Scratch CMP Polishing
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Solution Overview
Problem
Existing ceria particles used in semiconductor polishing processes have angular shapes that cause scratches and are thermodynamically unstable, leading to agglomeration and poor dispersibility, which affects polishing efficiency and selectivity.
Innovation Solution
An aqueous dispersion of inorganic particles with a mixed crystalline and amorphous phase, forming spherical shapes with surface protrusions, stabilized by amino acids and controlled surface charge, enhances polishing efficiency and selectivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional ceria particles with angular fluorite structure are used for polishing, then polishing speed for silicon oxide films is high, but scratch defects occur due to the angled structure
Solution Approach 1:
The patent applies spheroidality by transforming the angular fluorite structure ceria particles into spherical-shaped particles. This is achieved through controlled synthesis methods that produce particles with rounded surfaces, eliminating the sharp edges and angles that cause scratching during polishing while maintaining the ceria material's high polishing speed capability for silicon oxide films
2Object-affected harmful factors
If methods to prepare spherical ceria particles are used, then scratch damage is reduced, but it is very difficult to synthesize particles that are uniform in size and well dispersed
Solution Approach 1:
The patent applies parameter changes by precisely controlling synthesis conditions including temperature, pH, precursor ratios, and reaction time to produce spherical ceria particles with uniform size distribution. The controlled synthesis process adjusts chemical parameters to achieve consistent nucleation and growth, resulting in monodisperse spherical particles that maintain both low scratch damage and high size uniformity
Solution Approach 2:
The patent applies composite materials by combining ceria particles with specific size distributions and surface treatments to create a composite polishing slurry system. This composite approach uses multiple particle sizes or surface-modified particles to achieve both spherical morphology for reduced scratching and uniform dispersion characteristics for consistent polishing performance
3Quantity of substance
If inorganic particles are synthesized with high specific surface area, then catalytic reactivity is improved, but dispersion stability in aqueous solutions deteriorates due to thermodynamic instability
Solution Approach 1:
The patent applies intermediary by introducing dispersants or surface modifiers as mediating substances between the inorganic particles and aqueous solution. These intermediaries adsorb onto the particle surfaces, providing steric or electrostatic stabilization that prevents agglomeration of high-surface-area nanoparticles while maintaining their dispersibility and catalytic activity in aqueous environments
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 spherical particles with controlled surface charge improve polishing speed and reduce scratches, achieving high removal rates and stable dispersion in CMP processes.
Implementation Method 1
formed by self-assembly of a surfactant and inorganic precursor
Implementation Method 2
elementary particle has a mixed phase of a crystalline phase and an amorphous phase
Data Source
AI summary
Inorganic particles comprised in an aqueous dispersion according to the present invention consist of agglomerates of crystalline and amorphous microparticles, and exhibit spherical and smooth surfaces. The spherical appearance, low crystallinity, and narrow particle size distribution of the inorganic particles are further advantageous in reducing scratch defects in a CMP process. In addition, since the microparticles on the inorganic particle surfaces provide more active sites and thus the removal rate is high, the inorganic particles may be advantageous as next-generation CMP polishing materials. In addition, the aqueous dispersion according to the present invention further comprises an amino acid, and the amino acid may be adsorbed on a surface of a silicon oxide wafer to strengthen electrostatic attraction between the silicon oxide wafer and the inorganic particles, resulting in an effect of further improving the removal rate.