Graphene Liner and Cap Structure for Low-Resistance Copper Interconnects
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Solution Overview
Problem
Copper used in semiconductor structures undergoes high diffusion rates, leading to increased resistivity and potential device failures, while barrier layers used to prevent diffusion increase contact resistance.
Innovation Solution
A bi-layer liner and cap structure using graphene adjacent to copper conductive structures, combined with barrier layers and metal liners, to reduce surface scattering and contact resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If barrier layers are used to prevent copper diffusion, then copper diffusion is reduced, but contact resistance increases
Solution Approach 1:
The barrier structure is segmented into multiple functional layers: a diffusion barrier layer (e.g., tantalum nitride) to prevent copper migration, and a separate graphene liner layer to reduce contact resistance. This segmentation allows each layer to optimize its specific function without compromising the other.
Solution Approach 2:
Graphene serves as an intermediary layer between the copper conductive structure and the dielectric material. It mediates the interaction by providing a low-resistance interface that prevents direct contact between copper and dielectric, thereby reducing contact resistance while the underlying barrier layer handles diffusion prevention.
2Reliability
If copper is used for electrical connection, then electrical conductivity is improved, but surface scattering increases
Solution Approach 1:
A thin graphene film is applied as a liner on the copper conductive structure. This ultra-thin flexible film reduces surface scattering effects at the copper-dielectric interface while maintaining the excellent electrical conductivity of the underlying copper structure.
3Object-affected harmful factors
If metal liners are used to reduce contact resistance, then contact resistance is reduced, but device complexity increases
Solution Approach 1:
The invention changes the material parameter of the liner from conventional metals to graphene, which has superior electrical conductivity and atomic-thin thickness. This parameter change reduces contact resistance more effectively than traditional metal liners while the atomic thickness minimizes the added structural complexity.
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 layers reduce surface scattering and contact resistance, improving the electrical performance of semiconductor structures by preventing copper diffusion and maintaining low resistivity.
Implementation Method 1
The graphene liner reduces surface scattering at an interface between at least one metal of the bi-layer liner and the copper conductive structure
Implementation Method 2
Copper used in semiconductor structures undergoes high diffusion rates, leading to increased resistivity
Data Source
AI summary
A graphene liner deposited between at least one liner material (e.g., barrier layer, ruthenium liner, and/or cobalt liner) and a copper conductive structure reduces surface scattering at an interface between the at least one liner material and the copper conductive structure. Additionally, or alternatively, the carbon-based liner reduces contact resistance at an interface between the at least one liner material and the copper conductive structure. A carbon-based cap may additionally or alternatively be deposited on a metal cap, over the copper conductive structure, to reduce surface scattering at an interface between the metal cap and an additional copper conductive structure deposited over the metal cap.