Ceria-Based Composite Particle Dispersion for High-Rate CMP
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Solution Overview
Problem
Existing ceria-based composite particles used in chemical mechanical polishing (CMP) for semiconductor devices suffer from low polishing rates and surface defects due to low crystallinity and poor binding of ceria particles, leading to scratches and residue on the substrate.
Innovation Solution
A ceria-based composite particle dispersion with a cerium-containing silica layer and crystalline ceria particles, where the ceria particles are dispersed inside the silica layer and have a crystallite size of 10 to 25 nm, and an easily soluble silica layer as the outermost layer, enhancing polishing efficiency and surface accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If ceria particles are used for high polishing rate on silicon oxide film, then polishing rate is improved, but scratches and surface defects increase
Solution Approach 1:
The ceria-based composite particle is segmented into multiple functional layers: a mother particle (silica-based), a cerium-containing silica layer, child particles (crystalline ceria), and an easily soluble silica-containing outer layer. This segmentation allows each layer to perform its specific function - the crystalline ceria provides high polishing rate while the silica layers control surface quality and prevent scratches
Solution Approach 2:
The invention uses composite materials by combining silica-based mother particle with crystalline ceria child particles in a cerium-containing silica layer, and further coating with easily soluble silica-containing layer. This composite structure integrates the high polishing rate advantage of ceria with the surface quality benefits of silica, resolving the contradiction between polishing rate and surface accuracy
2Ease of manufacture
If amorphous ceria particles are used, then manufacturing is simpler, but crystallinity and binding strength are insufficient causing particle residue
Solution Approach 1:
The invention performs preliminary crystallization of ceria particles during the firing step before dispersion. By controlling the firing conditions (900-1200°C for 1-12 hours), the ceria particles are pre-formed with high crystallinity and strength, ensuring they will not cause surface defects during subsequent polishing operations
Solution Approach 2:
The invention changes the crystalline state parameter of ceria from amorphous to crystalline by controlling firing temperature and time. This parameter change transforms the ceria particles to have sufficient binding strength and structural integrity, preventing particle residue while maintaining manufacturing feasibility
3Manufacturing precision
If ceria particle size is reduced to increase uniformity, then particle size uniformity is improved, but polishing rate decreases
Solution Approach 1:
The invention applies local quality by having child particles (crystalline ceria) dispersed within the cerium-containing silica layer on the surface of the mother particle. This ensures that the high-polishing-rate crystalline ceria is concentrated at the active polishing interface, while the overall particle size uniformity is maintained through controlled synthesis of the composite structure
4Productivity
If rough primary polishing is performed first, then material removal efficiency is improved, but surface defects and scratches increase
Solution Approach 1:
The ceria-based composite particle achieves multi-functionality by combining multiple functions in one particle: the crystalline ceria child particles provide high polishing rate for efficient material removal, while the silica-based mother particle and easily soluble silica-containing outer layer provide surface quality control and scratch prevention. This single composite particle can perform both rough and finish polishing functions
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 ceria-based composite particle dispersion achieves high polishing rates with reduced scratches and improved surface accuracy, effectively polishing silica films and hard-to-process materials, while minimizing abrasive particle residue on the substrate.
Implementation Method 1
the crystalline ceria which is a major ingredient of the child particle has silicon atom solid-solubilized therein
Implementation Method 2
the abrasive particle takes part in polishing based on mechanical action
Implementation Method 3
the chemical ingredient takes part in promoting polishing through oxidation and corrosion of a target film
Implementation Method 4
having an easily soluble silica-containing layer as the outermost layer
Implementation Method 5
a cerium-containing silica layer, wherein the child particle is dispersed inside the cerium-containing silica layer
Data Source
AI summary
Aiming at providing a ceria-based composite particle dispersion capable of polishing silica film, Si wafer or even hard-to-process material at high polishing rate, and can give high surface accuracy, disclosed is a ceria-based composite particle dispersion that contains a ceria-based composite particle that has an average particle size of 50 to 350 nm, to solve the aforementioned problem, featured by that the ceria-based composite particle has a mother particle, a cerium-containing silica layer, a child particle, and an easily soluble silica-containing layer; the mother particle contains amorphous silica as a major ingredient; the child particle contains crystalline ceria as a major ingredient; ratio of the mass of the easily soluble silica-containing layer relative to the mass of the ceria-based composite particle falls in a specific range; mass ratio of silica and ceria in the ceria-based composite particle falls in a specific range; the ceria-based composite particle, when analyzed by X-ray diffractometry, shows only a crystal phase of ceria; and the ceria-based composite particle has an average crystallite size of the crystalline ceria, when analyzed by X-ray diffractometry, of 10 to 25 nm.