CMP Polishing Composition for Oxide-Nitride Selectivity
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Solution Overview
Problem
The existing chemical mechanical polishing (CMP) techniques struggle to achieve a high selection ratio of polishing removal rates for silicon oxide or silicon nitride compared to polysilicon and fail to adequately reduce organic residues on polished surfaces.
Innovation Solution
A polishing composition comprising colloidal silica, an inorganic salt without halogens, and a water-soluble polymer, where the product of the anion's valence number and concentration is 57 or more, enhancing the selection ratio and reducing organic residues by improving surface hydrophilicity and electrostatic repulsion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional CMP techniques are used to polish composite materials containing polysilicon and silicon oxide or silicon nitride, then polishing can be performed, but the selection ratio of polishing removal rates is substantially equal and residues remain insufficiently reduced
Solution Approach 1:
The patent changes the chemical parameters of the polishing composition by using colloidal silica with specific particle size distribution (0.01-10 μm), controlling pH (2-6), and adjusting the concentration ratio of silica particles to organic acid (1:0.1-10). These parameter changes create optimal conditions for selective removal of silicon oxide/nitride while minimizing polysilicon removal and residue formation.
Solution Approach 2:
The patent employs a composite polishing composition containing multiple components: colloidal silica particles, organic acid (immobilized on silica surface), wetting agent, and polishing removal rate inhibitor. This composite formulation works synergistically to achieve high selection ratio and reduced residues, where each component contributes specific functions for selective chemical-mechanical polishing.
2Productivity
If polishing composition with equal removal rates for different materials is used, then general polishing can be achieved, but the selection ratio between silicon oxide/nitride and polysilicon cannot be improved
Solution Approach 1:
The patent applies local quality by creating chemically active sites specifically on the silica particle surfaces through immobilization of organic acid. This localized chemical activity enhances the polishing removal rate of silicon oxide and silicon nitride selectively at the contact points between polishing composition and workpiece, while maintaining controlled removal of polysilicon through the inhibitor system.
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 a higher selection ratio of polishing removal rates for silicon oxide or silicon nitride to polysilicon and significantly reduces organic residues on the polished surface, improving the CMP process efficiency.
Implementation Method 1
a phenomenon that a reduction in residues on an object to be polished after polishing (polished object to be polished) is insufficient is also observed
Implementation Method 2
improving surface hydrophilicity and electrostatic repulsion
Implementation Method 3
A chemical mechanical polishing (CMP) method is one of them
Implementation Method 4
a chemical mechanical polishing (CMP) method
Data Source
AI summary
The present invention provides a method capable of increasing a ratio (selection ratio) of a polishing removal rate of silicon oxide or silicon nitride to a polishing removal rate of polysilicon and further reducing residues (preferably organic residues) on a surface of a polished object to be polished. The present invention is a polishing composition containing colloidal silica, an inorganic salt containing no halogen, and a water-soluble polymer, in which a product of a valence number (unit: valency) of an anion of the inorganic salt and a concentration (unit: mM) of the anion in the polishing composition is 57 or more.