Aminosilane Silica-Coated Ceria CMP Slurry for Low-Defect Polishing
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Solution Overview
Problem
Conventional CMP compositions face challenges in achieving high dielectric removal rates while minimizing surface defects, particularly when using ceria abrasive compounds.
Innovation Solution
A chemical mechanical polishing composition comprising silica-coated ceria particles modified with aminosilane compounds and maintained at a pH of less than about 7, which provides a positive charge and enhances polishing efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If ceria abrasive compounds are used to achieve high removal rates, then dielectric removal rate is improved, but surface defects increase
Solution Approach 1:
The patent uses composite ceria particles with a core-shell structure where a silica coating is applied over a ceria core. This composite structure allows the inner ceria to provide high removal rate while the outer silica coating suppresses surface defects and controls particle behavior during polishing.
Solution Approach 2:
The patent modifies the surface properties of ceria particles by changing the chemical composition and surface charge characteristics. The silica coating alters the particle's surface chemistry, and the aminosilane modification creates a positive charge that enhances polishing performance while reducing defects.
2Productivity
If ceria particles are used to maintain high removal rates, then productivity is improved, but manufacturing precision deteriorates due to increased surface roughness
Solution Approach 1:
The composite ceria-silica particle structure enables simultaneous achievement of high removal rate and low surface roughness. The silica outer layer acts as a protective and controlling interface that moderates the abrasive action of the inner ceria core, resulting in smoother surfaces.
Solution Approach 2:
The patent applies different functional properties to different parts of the particle structure: the inner ceria core provides high removal rate capability, while the outer silica layer provides surface quality control. This local differentiation of material properties resolves the contradiction between removal rate and surface finish.
3Productivity
If conventional ceria particles are used, then removal rate is improved, but defect count increases
Solution Approach 1:
The silica coating acts as an intermediary layer between the ceria core and the dielectric substrate. This intermediate layer mediates the interaction during polishing, allowing effective material removal while preventing direct contact between the ceria core and substrate that would cause defects.
Solution Approach 2:
The composite particle structure with silica coating over ceria core provides both high removal rate and low defect count by combining the advantageous properties of both materials in a functional hierarchy.
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 high dielectric removal rates with reduced defects, such as low scratch counts and surface roughness, making it suitable for polishing dielectric layers like silicon oxide.
Implementation Method 1
an aminosilane compound covalently bonded to an external surface of the silica coating such that the silica coated ceria particles have a positive charge in the polishing composition
Implementation Method 2
silica coated ceria particles having a silica coating over a ceria core
Implementation Method 3
The relative motion of the substrate and pad abrades and removes a portion of the material from the surface of the substrate
Data Source
AI summary
A chemical mechanical polishing composition comprises, consists of, or consists essentially of an aqueous based liquid carrier and silica coated ceria particles in the liquid carrier. The silica coated ceria particles include a silica coating over a ceria core and an aminosilane compound covalently bonded to an external surface of the silica coating such that the silica coated ceria particles have a positive charge in the polishing composition. The pH of the composition is less than about 7.