Graphene Capping for Copper Interconnects
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Solution Overview
Problem
Copper used in back-end-of-the-line (BEOL) interconnect structures is prone to oxidation and copper ion diffusion, leading to void formation and electromigration issues, which existing capping layers and diffusion barriers do not adequately address without increasing resistivity.
Innovation Solution
A contiguous layer of graphene is formed on exposed sidewall surfaces and the topmost surface of copper-containing structures to prevent copper oxidation and ion diffusion, enhancing electromigration resistance without increasing the resistivity of the copper.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional capping layers and diffusion barriers are used to protect copper, then copper oxidation and diffusion are reduced, but the resistivity of the copper structure increases
Solution Approach 1:
Graphene serves as an intermediary material between copper and the environment, providing oxidation protection and diffusion barrier functions while maintaining electrical conductivity. The single-layer graphene structure acts as a mediator that blocks copper ion diffusion into the dielectric material without introducing significant resistance to copper current flow.
Solution Approach 2:
The invention changes the material parameter from traditional thick capping layers to atomically thin graphene layers. This parameter change reduces the thickness from nanometer-scale dielectric layers to sub-nanometer graphene layers, minimizing the impact on electrical resistance while maintaining protective functions through the unique electronic structure of graphene.
2Object-affected harmful factors
If exposed copper surfaces are passivated with dielectric layers, then oxidation is prevented, but the surface area for heat dissipation decreases
Solution Approach 1:
Graphene provides an ultrathin protective shell around the copper structure. This flexible, atomically thin film prevents oxidation while maintaining thermal contact with the copper substrate. The thinness of the graphene layer (single atom thickness) ensures minimal thermal resistance, allowing efficient heat dissipation from the copper interconnect.
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 graphene layer effectively reduces copper oxidation and surface diffusion, improving the electromigration resistance of the BEOL interconnect structure without increasing the resistance of the copper-containing structure.
Implementation Method 1
The presence of the contiguous layer of graphene on the copper-containing structure reduces copper oxidation
Implementation Method 2
The presence of the contiguous layer of graphene on the copper-containing structure reduces copper oxidation and surface diffusion of copper ions
Implementation Method 3
The presence of the contiguous layer of graphene on the copper-containing structure reduces copper oxidation and surface diffusion of copper ions and thus improves the electromigration resistance of the structure
Data Source
AI summary
A contiguous layer of graphene is formed on exposed sidewall surfaces and a topmost surface of a copper-containing structure that is present on a surface of a substrate. The presence of the contiguous layer of graphene on the copper-containing structure reduces copper oxidation and surface diffusion of copper ions and thus improves the electromigration resistance of the structure. These benefits can be obtained using graphene without increasing the resistance of copper-containing structure.