Non-aqueous CMP Slurry for Galvanic Corrosion Control
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Solution Overview
Problem
Galvanic corrosion between conductive and barrier metals during chemical mechanical polishing (CMP) processes in semiconductor fabrication leads to surface irregularities, affecting interconnect reliability and manufacturing yield due to the use of aqueous CMP slurries that facilitate corrosion.
Innovation Solution
Employing a non-aqueous solvent-based CMP slurry with abrasive particles and chemical additives like oxidizing agents, chelating agents, and corrosion inhibitors to reduce galvanic corrosion, while maintaining effective polishing efficiency and planarization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If aqueous CMP slurry is used, then polishing effectiveness is improved, but galvanic corrosion between conductive and barrier metals increases
Solution Approach 1:
The patent changes the chemical composition parameter of the CMP slurry by replacing water with organic solvents (alcohols, esters, ethers, or their mixtures). This parameter change reduces the slurry's conductivity and eliminates ion dissociation, thereby preventing galvanic corrosion while maintaining polishing effectiveness through the action of abrasive particles and chemical additives.
Solution Approach 2:
The patent introduces organic solvent molecules as intermediaries between the conductive and barrier metals during CMP. These organic solvent molecules replace water molecules in the slurry, acting as a mediating substance that prevents direct electrochemical interaction between dissimilar metals while still allowing mechanical abrasion and chemical modification to occur.
2Object-generated harmful factors
If non-aqueous solvent is used, then galvanic corrosion is reduced, but polishing efficiency may be compromised
Solution Approach 1:
The patent creates a composite CMP slurry system combining organic solvents with carefully selected abrasive particles (such as colloidal silica, alumina, or ceria) and chemical additives (oxidizing agents, chelating agents, or corrosion inhibitors). This composite formulation ensures that the non-aqueous slurry maintains adequate polishing efficiency through the synergistic action of mechanical abrasion and chemical modification while preventing galvanic corrosion.
Solution Approach 2:
The patent adjusts multiple parameters of the non-aqueous slurry including solvent type (alcohol, ester, ether), abrasive particle size and composition, and chemical additive concentrations to optimize polishing efficiency. By tuning these parameters, the slurry achieves sufficient material removal rate and surface planarity while maintaining low conductivity to prevent corrosion.
3Productivity
If aqueous slurry is used, then material removal is effective, but surface planarity and interconnect reliability deteriorate due to corrosion
Solution Approach 1:
The patent changes the fundamental chemical parameter of the slurry from aqueous to non-aqueous composition. This parameter change eliminates water-induced galvanic corrosion that degrades surface planarity and interconnect reliability, while the adjusted abrasive and chemical composition maintains effective material removal capabilities for achieving flat surfaces.
Solution Approach 2:
The patent converts the potential harm of using organic solvents (which might be expected to reduce polishing effectiveness) into a benefit by demonstrating that non-aqueous solvents can provide both effective material removal and corrosion prevention. The harmful effect of water-induced corrosion is eliminated while the useful effect of material removal is maintained through optimized slurry formulation.
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 non-aqueous solvent reduces conductivity and ion dissociation, minimizing corrosion and enhancing the planarity and reliability of interconnect structures, thereby improving manufacturing yield and reducing defects.
Implementation Method 1
The non-aqueous solvent reduces conductivity and ion dissociation, minimizing corrosion
Implementation Method 2
a polishing composition, also referred to as CMP slurry, is introduced on to the workpiece. The rotating polishing pad and the CMP slurry together remove material from the workpiece
Implementation Method 3
a workpiece, such as a semiconductor wafer, is brought into physical contact with a rotating polishing pad
Implementation Method 4
chemical additives like oxidizing agents, chelating agents, and corrosion inhibitors
Data Source
AI summary
A polishing composition for a chemical mechanical polishing process includes abrasive particles, at least one chemical additive, and a non-aqueous solvent.