Graphene-Clad Copper Interconnects for Low-Resistance Scaling
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Solution Overview
Problem
The challenge in semiconductor manufacturing is the complexity of scaling down metal oxide semiconductor field effect transistors (MOSFETs) and fin field effect transistors (FinFETs) due to increased complexity in metal interconnects, which requires improved materials to reduce resistivity and prevent diffusion and corrosion.
Innovation Solution
The use of graphene cladding on copper interconnects to form graphene-clad metal interconnects, which reduces resistance and acts as a diffusion barrier, enhancing electrical and thermal conductivity while preventing copper oxidation and corrosion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If metal interconnect dimensions are scaled down to meet higher storage capacity and processing speed demands, then device performance improves, but manufacturing complexity and resistivity increase
Solution Approach 1:
The patent applies composite materials by combining copper interconnects with graphene cladding layers. The copper provides high electrical conductivity while the graphene layer acts as a diffusion barrier and reduces electromigration, creating a composite structure that overcomes the limitations of pure metal interconnects at scaled dimensions
Solution Approach 2:
The patent changes the physical and chemical parameters of the interconnect system by introducing graphene cladding with specific thickness ranges (1-10 nm). This modifies the electrical, thermal, and mechanical properties of the interconnect, reducing resistivity and preventing copper diffusion into surrounding dielectric materials
2Volume of moving object
If metal interconnect dimensions are scaled down, then device size reduces, but resistivity increases
Solution Approach 1:
The copper-graphene composite structure maintains low resistivity by combining the high electrical conductivity of copper with the surface conductivity of graphene. The graphene layer compensates for increased resistivity that would normally occur at scaled dimensions
Solution Approach 2:
The graphene cladding is applied selectively to the surface of the copper interconnect, providing local enhancement of electrical and thermal conductivity at the interfaces where electromigration and diffusion are most problematic, while maintaining the bulk copper's conductivity
3Reliability
If copper interconnects are used to maintain electrical conductivity, then electrical performance is good, but diffusion and corrosion occur
Solution Approach 1:
The graphene layer serves as an intermediary between the copper interconnect and the surrounding dielectric environment. It prevents direct contact between copper and oxidizing agents or diffusing species, thereby eliminating corrosion and diffusion while maintaining electrical conductivity through the graphene-copper interface
Solution Approach 2:
The patent converts the potential harm of copper diffusion and oxidation into a benefit by using the same copper material's ability to form controlled interfaces with graphene. The graphene cladding transforms what would be harmful diffusion paths into protected conduction paths
4Reliability
If graphene cladding is applied to reduce resistance and prevent diffusion, then electrical conductivity improves, but manufacturing complexity increases
Solution Approach 1:
The graphene cladding is applied in advance to the copper interconnect structure before final assembly and operation. This preliminary protection layer is deposited during the interconnect fabrication process, preventing diffusion and corrosion before they can occur during subsequent manufacturing steps or device operation
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
Graphene-clad metal interconnects significantly reduce resistance by up to 50% and extend the lifespan of copper metal lines, improving capacitance and reliability by acting as a diffusion barrier and reducing electromigration.
Implementation Method 1
graphene cladding on copper interconnects to form graphene-clad metal interconnects, which reduces resistance and acts as a diffusion barrier, enhancing electrical and thermal conductivity
Implementation Method 2
acts as a diffusion barrier, enhancing electrical and thermal conductivity while preventing copper oxidation and corrosion
Implementation Method 3
extending the lifespan of copper metal lines, improving capacitance and reliability by acting as a diffusion barrier and reducing electromigration
Data Source
AI summary
A graphene-clad metal interconnect extends material properties of graphene to both damascene and patterned interconnect structures at lower metal layers, leading to significant reductions in resistance. Graphene cladding can be used with or without a metal barrier/liner. Presence of a barrier/liner can serve to catalyze growth of an overlying graphene layer. Graphene may also be selectively grown on barrier surfaces. Fully integrated structures and process flows for integrated circuits with graphene-clad metallization are described.