Cobalt CMP Slurry Using Alternative Oxidizers for Low Defectivity
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Solution Overview
Problem
Current CMP methods for cobalt integration in integrated circuits face limitations with hydrogen peroxide as the oxidizing agent, exhibiting compatibility issues and stability problems, leading to suboptimal cobalt removal rates, planarization efficiency, and high defectivity.
Innovation Solution
A chemical-mechanical polishing composition incorporating an abrasive, a cobalt accelerator (iminodiacetic acid, glycine, or picolinic acid), and an oxidizing agent (4-nitropyridine, 4-nitropyridine N-oxide, or 4-methoxypyridine N-oxide) with a pH of 5 to 9, enhancing cobalt removal rates and planarization efficiency while reducing dishing and erosion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If hydrogen peroxide is used as the oxidizing agent in CMP composition, then cobalt removal rate can be achieved, but compatibility issues and stability problems occur leading to high defectivity
Solution Approach 1:
The patent changes the chemical parameters of the oxidizing agent from hydrogen peroxide to alternative oxidizing agents (such as ammonium persulfate, potassium persulfate, sodium persulfate, or ammonium peroxodisulfate) to resolve the contradiction between removal rate and defectivity. This parameter change maintains effective cobalt removal while improving slurry stability and reducing defects
Solution Approach 2:
The patent replaces the unstable hydrogen peroxide system with more stable alternative oxidizing agents that have better shelf life and compatibility. These alternative agents provide consistent performance without the degradation issues of hydrogen peroxide, effectively treating the oxidizing agent as a consumable that needs frequent replacement with a more reliable formulation
2Power
If hydrogen peroxide is used as the oxidizing agent, then oxidation of cobalt can occur, but compatibility issues with other slurry components arise
Solution Approach 1:
The patent changes the chemical identity of the oxidizing agent to alternatives such as ammonium persulfate, potassium persulfate, sodium persulfate, or ammonium peroxodisulfate. These agents maintain the necessary oxidation power for cobalt removal while demonstrating superior compatibility with other slurry components including complexing agents and abrasives
Solution Approach 2:
The patent creates a composite CMP slurry formulation that integrates alternative oxidizing agents with complexing agents (such as ammonia, ammonium hydroxide, or amines) and other slurry components. This composite formulation achieves synergistic effects where the alternative oxidizing agent works harmoniously with other components to provide both high removal rate and excellent planarization
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 high cobalt removal rates with low defectivity and improved planarization efficiency, addressing the limitations of hydrogen peroxide-based systems.
Implementation Method 1
an oxidizing agent that oxidizes a metal, wherein the oxidizing agent is selected from 4-nitropyridine, 4-nitropyridine N-oxide, 4-methoxypyridine N-oxide
Implementation Method 2
a chemical-mechanical polishing composition comprising (a) an abrasive
Implementation Method 3
a cobalt accelerator, wherein the cobalt accelerator is present in the polishing composition at a concentration of 5 mM to 100 mM, the cobalt accelerator is selected from iminodiacetic acid, glycine, and picolinic acid
Data Source
AI summary
The invention provides a chemical-mechanical polishing composition comprising (a) an abrasive, (b) a cobalt accelerator, and (c) an oxidizing agent that oxidizes a metal, wherein the polishing composition has a pH of about 4 to about 10. The invention further provides a method of chemically-mechanically polishing a substrate with the inventive chemical-mechanical polishing composition. Typically, the substrate contains cobalt.