High-pH CMP Cleaning Composition for Ceria Residue Removal
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Solution Overview
Problem
Ceria-based CMP slurries are difficult to remove from microelectronic device surfaces due to oppositely charged zeta potentials, leading to residue issues that cause short circuits and increased electrical resistance, and existing cleaning compositions struggle with post-CMP residue removal from dielectric surfaces like PETEOS and silicon nitride, resulting in high defectivity.
Innovation Solution
A high pH cleaning composition comprising water, an alkanolamine, a glycol ether, a pH adjustor, and a surface-active hydrophobic acid is used to improve surface wetting and dispersion of particles and residues, preventing redeposition and agglomeration, thereby enhancing cleaning efficacy and reducing defectivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If ceria-based CMP slurry is used for polishing, then polishing speed and planarization quality are improved, but residue removal becomes difficult due to oppositely charged zeta potentials
Solution Approach 1:
The patent changes the pH parameter of the cleaning composition to greater than 10, which fundamentally alters the surface charge characteristics of both the dielectric substrate and ceria particles. This pH parameter change overcomes the zeta potential attraction that causes residue adhesion, enabling effective residue removal while maintaining the benefits of ceria-based polishing
Solution Approach 2:
The patent introduces a specific cleaning composition as an intermediary substance between the ceria residue and the dielectric surface. This composition contains surfactants and chelating agents that mediate the interaction, allowing the residue to be removed despite the electrostatic attraction that would otherwise prevent removal
2Device complexity
If conventional cleaning compositions are used for post-CMP cleaning, then cleaning process is simple, but cleaning efficacy is poor with high residue and defectivity
Solution Approach 1:
The patent creates a composite cleaning composition that integrates multiple functional components: surfactants for surface activity, chelating agents for metal ion complexation, and pH adjustors for charge control. This composite formulation achieves superior cleaning quality by combining the effects of different material types in a single composition
Solution Approach 2:
The cleaning composition is designed to perform multiple functions simultaneously: it wetts the surface, disperses particles, chelates metal ions, and maintains appropriate pH levels. This multi-functionality allows a single composition to address all aspects of post-CMP cleaning without requiring multiple sequential processing steps
3Reliability
If high pH cleaning is applied to remove residues, then electrostatic repulsion should improve particle removal, but organic additives in CMP slurries neutralize repulsive forces and increase defectivity
Solution Approach 1:
The patent introduces surfactants as intermediary substances that interact with both the organic residue layers and the ceria particles. These surfactants disrupt the neutralizing effect of organic additives by competing for interaction sites, thereby restoring the electrostatic repulsion mechanism while preventing additional defect formation
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 effectively removes post-CMP residues from dielectric surfaces, achieving superior cleaning with low defectivity and ensuring the removal of ceria particles and other contaminants, thus preventing short circuits and electrical resistance issues.
Implementation Method 1
at pH greater than the pH IEP (isoelectric point), both abrasive residual particles and the dielectric surfaces should be highly negatively charged and thus, the electrostatic repulsion particle-substrate should result in lower defectivity
Implementation Method 2
strong interactions between the abrasive particles and dielectric surfaces via hydrogen-bonding and Van der Waals forces
Implementation Method 3
strong interactions between the abrasive particles and dielectric surfaces via hydrogen-bonding and Van der Waals forces
Implementation Method 4
The compositions of the invention afford superior surface wetting
Implementation Method 5
The compositions of the invention afford superior surface wetting
Implementation Method 6
dispersion of particles and organic residues, and prevents redeposition and re-agglomeration of the dispersed residue
Data Source
AI summary
In general, the invention provides high pH cleaning compositions for dielectric surfaces such as PETEOS, SiO2, thermal oxide, silicon nitride, silicon, etc. The compositions of the invention afford superior surface wetting, dispersion of particles and organic residues, and prevents redeposition and re-agglomeration of the dispersed residue during cleaning to afford superior cleaning and low defectivity.