CMP Slurry with Cationic Dispersants for Planarization Control
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Solution Overview
Problem
Current chemical mechanical polishing (CMP) technologies face challenges in achieving high selectivity and removal rates for high stepped portions in semiconductor manufacturing, while also preventing dishing and scratches, and efficiently reducing polishing speed after initial polishing.
Innovation Solution
An abrasive particle-dispersion layer composite is developed, comprising abrasive particles chemically bonded with cationic dispersants such as amino acids and cationic polymers, along with nonionic compounds, to enhance dispersibility and reduce particle aggregation, used in a polishing slurry composition with specific pH and zeta-potential ranges.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a single-layered slurry with anionic polymer and anionic copolymer is used, then high polishing rate and high selectivity are realized in high stepped portion, but it is difficult to adjust planarization degree and control dishing in low stepped portion
Solution Approach 1:
The slurry system is segmented into multiple functional layers: a first dispersant layer (anionic polymer) that provides high polishing rate and selectivity for stepped portions, and a second dispersant layer (cationic polymer) that controls planarization and prevents dishing in low stepped portions. Each layer performs its specific function independently, resolving the contradiction between high polishing rate and precise planarization control.
Solution Approach 2:
The invention uses a composite dispersant system combining anionic and cationic polymers with different functional properties. The anionic polymer provides aggressive polishing for high stepped portions, while the cationic polymer provides gentle planarization for low stepped portions, achieving both high productivity and manufacturing precision through material composition.
2Productivity
If abrasive particles with inherent hardness are used, then high removal rate is achieved, but scratches are highly likely to occur
Solution Approach 1:
The invention changes the surface charge parameter of abrasive particles from negative to positive through the use of cationic dispersants. This parameter change reduces the inherent hardness and aggressiveness of the abrasive particles, preventing scratches while maintaining removal rate through the synergistic action of multiple dispersant layers.
Solution Approach 2:
The cationic polymer acts as an intermediary between the abrasive particles and the workpiece surface. It coats the abrasive particles, reducing their direct contact hardness, and provides a lubricating effect that prevents scratches while allowing the abrasive particles to maintain their removal rate function.
3Manufacturing precision
If polishing is continued after step removal, then planarization is achieved, but polishing speed is considerably reduced
Solution Approach 1:
The invention creates a dynamic polishing system where the cationic polymer dispersant automatically adjusts the polishing speed based on the surface topography. In high stepped portions, the anionic polymer dominates providing high removal rate; in planarized low stepped portions, the cationic polymer dominates providing gentle planarization at reduced speed, achieving both precision and efficiency.
Solution Approach 2:
The dual-dispersant system provides inherent feedback control: the cationic polymer's planarization function activates when the anionic polymer has removed the stepped portions, automatically reducing polishing speed when planarization is needed without external intervention, thus maintaining both precision and productivity.
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 solution achieves high selectivity and removal rates for high stepped portions, implements an automatic polishing stop function, and effectively prevents dishing and scratches, ensuring high dispersion stability and polishing efficiency across various film types.
Implementation Method 1
abrasive particles, a first dispersant that is at least one cationic compound among an amino acid, an organic acid, polyalkylene glycol and a high-molecular polysaccharide coupled to a glucosamine compound
Implementation Method 2
A surface of the abrasive particles, the first dispersant and the second dispersant may have positive charges
Data Source
AI summary
An abrasive particle-dispersion layer composite and a polishing slurry composition including the abrasive particle-dispersion layer composite are provided. The abrasive particle-dispersion layer composite includes abrasive particles, a first dispersant that is at least one cationic compound among an amino acid, an organic acid, polyalkylene glycol and a high-molecular polysaccharide coupled to a glucosamine compound, and a second dispersant that is a cationic polymer including at least two ionized cations in a molecular formula.