Cerium Oxide Abrasive for Selective CMP Slurry
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Solution Overview
Problem
Conventional cerium oxide-based CMP slurries require additional additives to achieve high selectivity between silicon oxide and silicon nitride layers, leading to non-uniform polishing characteristics due to precipitation issues, and one-component slurries without additives suffer from inadequate selectivity and microscratch problems.
Innovation Solution
Cerium oxide powder with a high pore fraction and low strength, obtained through a low-temperature calcination and high-temperature calcination process, is used as an abrasive in a one-component CMP slurry, eliminating the need for additional additives and enhancing polishing selectivity and rate without causing surface scratches.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If additional additives (polycarboxylic acid-based anionic polymers) are added to increase selective polishing rate ratio, then polishing selectivity is improved, but abrasive particles precipitate severely and show non-uniform concentration
Solution Approach 1:
The invention extracts and eliminates the problematic additives (polycarboxylic acid-based anionic polymers) from the slurry formulation. By removing these additives entirely and relying on cerium oxide powder with optimized pore structure and low strength characteristics, the slurry achieves high polishing selectivity without the precipitation and non-uniformity issues caused by excessive dispersant addition.
Solution Approach 2:
The invention changes the physical and chemical parameters of the cerium oxide powder, specifically controlling pore fraction to 30-70% and strength to 0.5-5.0 gf. These parameter changes enable the abrasive particles to achieve high polishing selectivity through controlled fragmentation and chemical reaction mechanisms, eliminating the need for additives while maintaining slurry stability.
2Stability of the object's composition
If one-component slurry without additives is used, then slurry uniformity is improved, but polishing selectivity becomes inadequate and microscratch problems occur
Solution Approach 1:
The invention achieves high polishing selectivity in a one-component slurry by precisely controlling the pore fraction (30-70%) and strength (0.5-5.0 gf) parameters of the cerium oxide powder. These parameter changes enable the abrasive to provide both mechanical polishing action and chemical reaction capability, achieving selectivity ratios of 20:1 or higher without additives.
Solution Approach 2:
The invention creates a composite structure within the cerium oxide powder by incorporating a high pore fraction (30-70%) into the ceramic matrix. This composite structure provides both mechanical strength for abrasion and surface area for chemical reactions, enabling high polishing selectivity in a one-component slurry system.
3Strength
If cerium oxide powder with high strength is used, then mechanical durability is improved, but polishing selectivity decreases and dishing increases
Solution Approach 1:
The invention inverts the conventional approach by using cerium oxide powder with low strength (0.5-5.0 gf) rather than high strength. This inversion enables the abrasive particles to fragment more easily during polishing, providing finer particles that improve selectivity and reduce dishing, while the chemical reaction mechanism compensates for the reduced mechanical durability.
Solution Approach 2:
The invention changes the strength parameter of cerium oxide powder to a low range (0.5-5.0 gf) and combines it with high pore fraction (30-70%). This parameter change transforms the polishing mechanism from purely mechanical to a combination of mechanical action and chemical reaction, achieving high selectivity and reduced dishing.
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 cerium oxide powder with a specific surface area of 5 m2/g and a high volume fraction of pores provides excellent polishing selectivity and rate, maintaining high performance without additives, reducing microscratch, and achieving a selectivity ratio of 20:1 or higher between silicon oxide and silicon nitride layers.
Implementation Method 1
a low-temperature calcination step, a pulverization step and a high temperature calcination step
Implementation Method 2
polishing of a silicon oxide layer is made not only by a mechanical polishing action but also by a chemical reaction caused by cerium oxide
Implementation Method 3
a chemical reaction caused by cerium oxide
Data Source
AI summary
A cerium oxide powder for one-component CMP slurry, which has a specific surface area of 5 m2/g or more, and a ratio of volume fraction of pores with a diameter of 3 nm or more to that of pores with a diameter less than 3 nm of 8:2˜2:8, is disclosed. A method for preparing the same, a one-component CMP slurry comprising the same as an abrasive material, and a method of shallow trench isolation using the one-component CMP slurry are also disclosed. The CMP slurry causes no precipitation of the cerium oxide powder even if it is provided as a one-component CMP slurry, because the CMP slurry uses, as an abrasive material, cerium oxide powder that is obtained via a low-temperature calcination step, optionally a pulverization step, and a high-temperature calcination step and has a high pore fraction and low strength.