Graphene Selective Barrier for Interconnect Contact Resistance
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Solution Overview
Problem
As IC technology advances, the increasing complexity and compactness of interconnect and contact structures lead to higher contact resistance, causing signal delays and performance issues due to increased resistivity, particularly with the use of metal nitrides as barrier layers in advanced technology nodes.
Innovation Solution
The implementation of a graphene layer as a selective barrier layer, only formed on sidewalls, reducing contact resistance and serving as a blocking layer to prevent barrier layer deposition on the conduction path, thereby enhancing the reliability and performance of BEOL interconnect and MEOL contact structures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If metal nitride barrier layers are used in advanced technology nodes, then device reliability is improved, but contact resistance increases and signal routing efficiency deteriorates
Solution Approach 1:
The patent applies local quality by making the barrier layer selective in its deposition location. The barrier layer is deposited only on the sidewalls of the contact structure, while the top surface (conduction path) remains free of barrier material. This is achieved through selective area deposition techniques that control where the barrier layer forms, allowing the conductive metal to directly contact the underlying layer at the top surface while still providing barrier protection on the sidewalls.
Solution Approach 2:
The patent introduces a liner layer as an intermediary between the conductive metal and the barrier layer. This liner layer is deposited on the top surface where conduction occurs, allowing direct metal-to-substrate contact for low resistance, while the barrier layer is deposited on the sidewalls to prevent diffusion. The liner acts as a mediator that enables both low contact resistance and diffusion protection.
2Productivity
If interconnect and contact structures are scaled down to smaller feature sizes, then production efficiency is improved and costs are reduced, but contact resistance increases and signal routing efficiency deteriorates
Solution Approach 1:
The selective barrier layer deposition creates different material compositions at different locations within the contact structure. The top surface has a liner-free, direct metal contact for low resistance, while the sidewalls have barrier layer protection. This local differentiation allows the structure to maintain low contact resistance even at scaled dimensions.
Solution Approach 2:
The contact structure employs a composite material approach with multiple layers having different properties. The conductive metal provides electrical conduction, the liner layer provides a controlled interface, and the barrier layer provides diffusion protection. This composite structure optimizes both electrical performance and reliability at scaled dimensions.
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 use of a graphene layer significantly reduces contact resistance, decreases RC delay, and improves device performance by acting as a superior barrier and conductive interface, allowing for more efficient signal routing and operation of IC devices.
Implementation Method 1
The implementation of a graphene layer as a selective barrier layer, only formed on sidewalls, reducing contact resistance and serving as a blocking layer to prevent barrier layer deposition on the conduction path
Data Source
AI summary
Interconnect structures and method of forming the same are disclosed herein. An exemplary interconnect structure includes a first contact feature in a first dielectric layer, a second dielectric layer over the first dielectric layer, a second contact feature over the first contact feature, a barrier layer between the second dielectric layer and the second contact feature, and a graphene layer between the second contact feature and the first contact feature.