Copper-Passivating CMP Slurries for Etch Control
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Solution Overview
Problem
Conventional copper chemical-mechanical polishing (CMP) slurries face challenges with high chemical reactivity, leading to excessive copper static etch rates, dishing-erosion, defectivity, and surface topography issues, necessitating the development of compositions with reduced solids levels and improved corrosion protection.
Innovation Solution
The use of CMP compositions comprising a particulate abrasive, a copper-complexing agent, and a copper-passivating agent with an acidic OH group and an additional oxygen-bearing substituent in a 1,6 relationship, along with an oxidizing agent, to achieve high copper removal rates and effective passivation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional copper CMP slurries use high chemical reactivity to achieve high copper removal rates, then productivity is improved, but manufacturing precision deteriorates due to excessive static etch rates, dishing-erosion, and surface topography issues
Solution Approach 1:
The patent introduces a copper passivation layer as an intermediary between the abrasive and the copper substrate. This passivation layer moderates the interaction, allowing controlled material removal while preventing excessive etching and surface damage. The passivation layer acts as a mediator that enables high removal rates without sacrificing surface quality.
Solution Approach 2:
The patent changes the chemical parameters of the slurry by incorporating specific passivation agents and complexing agents. These parameter changes modify the chemical reactivity of the slurry, enabling it to achieve high copper removal rates while maintaining controlled etch rates and surface quality through adjusted chemical composition.
2Manufacturing precision
If conventional copper CMP slurries use high solids levels to improve mechanical abrasive properties, then manufacturing precision is improved, but loss of substance increases due to dishing-erosion
Solution Approach 1:
The passivation layer serves as an intermediary that protects the copper substrate from excessive mechanical abrasion. By controlling the interaction between the abrasive and the copper surface, the passivation layer reduces dishing-erosion and material loss while maintaining surface finish quality.
Solution Approach 2:
The patent converts the potentially harmful effect of mechanical abrasion into a beneficial process by using the passivation layer to control the abrasion. The mechanical action that would normally cause dishing-erosion is instead directed to remove the passivation layer in a controlled manner, revealing fresh copper surface without excessive material loss.
3Manufacturing precision
If conventional copper CMP slurries use organic corrosion inhibitors to control static etch rates, then manufacturing precision is improved, but reliability deteriorates due to poor corrosion control after polishing
Solution Approach 1:
The patent uses a passivation layer as a more durable intermediary compared to traditional corrosion inhibitors. This passivation layer provides both etch rate control during polishing and sustained corrosion protection after polishing, improving reliability without sacrificing manufacturing precision.
Solution Approach 2:
The patent employs a composite approach by combining passivation agents with complexing agents in the slurry formulation. This composite chemistry creates a more robust and durable protective effect on the copper surface, providing both precise etch control and long-term corrosion resistance.
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 described CMP compositions provide high copper removal rates with low defectivity and superior corrosion protection, as demonstrated by the examples using salicylhydroxamic acid and N-lauroyl sarcosine, which show controlled copper removal and passivation, reducing static etch rates and enhancing surface quality.
Implementation Method 1
a copper-complexing agent
Implementation Method 2
a copper-passivating agent
Implementation Method 3
an oxidizing agent
Implementation Method 4
a particulate abrasive
Data Source
AI summary
The present invention provides chemical-mechanical polishing (CMP) methods and compositions for polishing copper-containing substrates. The methods of the present invention entail abrading a surface of a copper-containing substrate with a CMP composition of the invention, preferably in the presence of an oxidizing agent (e.g., hydrogen peroxide). The CMP compositions of the invention comprise a particulate abrasive, a copper-complexing agent, a copper-passivating agent bearing an acidic OH group and an additional oxygen substituent in a 1,6 relationship to the acidic OH group, and an aqueous carrier. A preferred composition of the invention comprises about 0.01 to about 1 percent by weight of the particulate abrasive, about 0.1 to about 1 percent by weight of the copper-complexing agent, about 10 to about 1000 ppm of the copper-passivating agent.