CMP Slurry Passivating Films for Copper Etch Control
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Solution Overview
Problem
Conventional chemical-mechanical polishing (CMP) slurries for copper and silver substrates face challenges with high copper static etch rates, dishing-erosion, defectivity, and poor corrosion control, requiring improved compositions with balanced chemical reactivity and mechanical abrasive properties.
Innovation Solution
The development of CMP compositions incorporating a primary film-forming metal-complexing agent and a secondary film-forming metal-passivating agent, along with a particulate abrasive and an aqueous carrier, which form synergistic passivating films to reduce static etch rates and friction, thereby enhancing copper and silver removal rates and corrosion protection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional CMP slurries with high chemical reactivity are used, then copper removal rate is improved, but static etch rate increases and corrosion control deteriorates
Solution Approach 1:
The patent introduces an organic corrosion inhibitor as an intermediary substance that mediates between the chemically reactive CMP slurry and the copper substrate. The inhibitor adsorbs onto the copper surface, forming a protective layer that reduces direct interaction between aggressive slurry components and the metal, thereby lowering static etch rate while preserving removal rate benefits
Solution Approach 2:
The patent modifies the chemical composition parameters of the CMP slurry by adding specific concentrations of corrosion inhibitors (e.g., benzotriazole derivatives at 0.01-1.0 wt%). This parameter change alters the chemical reactivity profile of the slurry, reducing its aggressiveness toward copper and thereby controlling static etch rate without significantly impacting mechanical abrasive removal
2Productivity
If high abrasive concentration is used, then mechanical polishing capability is improved, but dishing-erosion and surface topography problems worsen
Solution Approach 1:
The patent optimizes the abrasive concentration parameter within a specific range (0.1-10 wt%, preferably 0.5-5 wt%) to balance mechanical polishing capability with surface quality. This parameter optimization ensures sufficient abrasive particles for effective material removal while preventing excessive mechanical stress that causes dishing and erosion
Solution Approach 2:
The patent creates a composite CMP slurry system combining abrasive particles with chemically active components (corrosion inhibitors, chelating agents, oxidizing agents). This composite formulation allows synergistic interaction where chemical softening of the copper surface precedes mechanical abrasion, reducing the mechanical load on abrasives and thereby minimizing dishing-erosion while maintaining polishing efficiency
3Productivity
If chemically reactive CMP composition is used, then copper removal rate is improved, but corrosion control after polishing deteriorates
Solution Approach 1:
The patent applies corrosion inhibitors in advance during the polishing process itself, rather than as a post-treatment. The inhibitors are pre-loaded into the CMP slurry and act on the copper surface during polishing, forming a protective film before the substrate is exposed to the corrosive environment after polishing, thereby providing proactive corrosion protection
Solution Approach 2:
The corrosion inhibitor serves as an intermediary layer between the copper substrate and the aggressive CMP slurry components. This intermediary substance adsorbs onto the copper surface and forms a protective barrier that prevents direct contact between corrosive ions and the metal, thereby improving corrosion control while allowing the slurry to maintain its chemically reactive nature for effective material removal
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 CMP compositions achieve high removal rates with low static etch rates and friction, improved surface passivation, and superior corrosion protection compared to conventional slurries, addressing issues of dishing-erosion and defectivity.
Implementation Method 1
a primary film-forming metal-complexing agent and a secondary film-forming metal-passivating agent, along with a particulate abrasive and an aqueous carrier, which form synergistic passivating films
Implementation Method 2
utilizing a combination of a film-forming metal-complexing agent and a metal-passivating agent
Implementation Method 3
The relative movement of the pad and substrate serves to abrade the surface of the substrate to remove a portion of the material from the substrate surface
Implementation Method 4
The abrasive desirably is suspended in the CMP composition as a colloidal dispersion
Implementation Method 5
The polishing of the substrate surface typically is further aided by the chemical activity of the polishing composition (e.g., by oxidizing agents present in the CMP composition)
Data Source
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Figure 2A~2B
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AI summary
The present invention provides chemical-mechanical polishing (CMP) compositions and methods for polishing copper- and/or silver-containing substrates. The compositions of the present invention comprise a particulate abrasive, a primary film-forming metal-complexing agent, and a secondary film-forming metal-passivating agent in an aqueous carrier. Methods of polishing a substrate with the compositions of the invention are also disclosed.