Graphite Interconnect Structure Without Diffusion Barrier Layers
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Solution Overview
Problem
Conventional interconnect structures in integrated circuits face challenges as the width of metal lines decreases below 10 nm, leading to increased resistivity and insufficient copper region thickness due to the need for thicker diffusion barrier layers.
Innovation Solution
The use of graphite conductive features eliminates the need for a diffusion barrier layer, allowing for reduced lateral dimensions of conductive features and maintaining effective electrical connectivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If copper interconnect structures are scaled down to widths smaller than 10 nm, then the interconnect density is improved, but the resistivity of copper increases significantly
Solution Approach 1:
The patent changes the material parameter from copper to graphite, which has fundamentally different electrical properties. Graphite maintains low resistivity at nanoscale dimensions where copper resistivity increases significantly, thus resolving the contradiction between achieving high interconnect density and maintaining low resistivity.
Solution Approach 2:
The patent employs a composite structure consisting of graphite conductive material within a dielectric matrix. This composite approach allows the graphite to provide excellent electrical conductivity at nanoscale while the dielectric provides structural support and isolation, achieving both high density and low resistivity.
2Productivity
If the width of metal lines is reduced below 10 nm, then the interconnect scaling is improved, but the thickness of the barrier layer becomes an increasingly greater portion of the interconnect structure
Solution Approach 1:
The patent extracts and eliminates the barrier layer from the interconnect structure by using graphite as the conductive material. Graphite naturally forms stable interfaces with dielectric materials without requiring separate barrier layers, thus removing the problematic component that was consuming excessive thickness proportion in scaled-down structures.
Solution Approach 2:
The patent applies local quality by using graphite specifically in the conductive region where nanoscale performance is critical. This material choice provides locally optimized properties: excellent electrical conductivity and natural interface stability at the nanoscale, eliminating the need for additional barrier layer complexity.
3Reliability
If the barrier layer thickness is increased to prevent copper diffusion, then the diffusion prevention is improved, but the available thickness for the copper region is reduced
Solution Approach 1:
The patent removes the barrier layer entirely from the structure by replacing copper with graphite. Graphite's atomic structure provides inherent diffusion resistance at interfaces without requiring separate barrier layers, thus eliminating the trade-off between barrier thickness and conductor thickness.
Solution Approach 2:
The patent changes the material parameter from copper (which requires thick barrier layers for diffusion prevention) to graphite (which provides inherent diffusion resistance). This material substitution resolves the contradiction by providing both diffusion prevention and sufficient conductive region thickness simultaneously.
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
Graphite interconnects achieve reduced resistivity and enable smaller feature sizes, advancing the scaling of integrated circuits without the need for thicker barrier layers.
Implementation Method 1
a graphite layer is deposited. The graphite layer is patterned to form conductive features
Data Source
AI summary
A method includes forming a first conductive feature, depositing a graphite layer over the first conductive feature, patterning the graphite layer to form a graphite conductive feature, depositing a dielectric spacer layer on the graphite layer, depositing a first dielectric layer over the dielectric spacer layer, planarizing the first dielectric layer, forming a second dielectric layer over the first dielectric layer, and forming a second conductive feature in the second dielectric layer. The second conductive feature is over and electrically connected to the graphite conductive feature.