Graphite Interconnect Structure Without Copper Barrier Layers
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Solution Overview
Problem
Conventional interconnect structures face challenges with increasing resistivity of copper lines as dimensions shrink below 10 nm, requiring thicker barrier layers that reduce the available space for copper, making it difficult to meet resistance requirements.
Innovation Solution
The use of graphite conductive features eliminates the need for a diffusion barrier layer, allowing for reduced lateral dimensions and maintaining low resistivity by patterning a graphite layer and depositing a spacer layer to prevent peeling, enabling smaller conductive feature sizes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If copper is used for interconnect lines with width smaller than 10 nm, then the interconnect structure can achieve small dimensions, but the resistivity of copper increases significantly
Solution Approach 1:
The patent changes the material parameter from copper to graphite, which fundamentally alters the electrical conductivity characteristics. Graphite maintains low resistivity at nanoscale dimensions where copper's resistivity increases significantly, thus resolving the contradiction between small dimensions and low resistivity.
Solution Approach 2:
The patent uses a composite structure consisting of graphite conductive material combined with a dielectric spacer layer. This composite approach allows the graphite to provide low resistivity while the spacer layer provides structural stability and prevents peeling, achieving both small dimensions and reliable electrical performance.
2Reliability
If a diffusion barrier layer is added to prevent copper diffusion, then copper diffusion is prevented, but the thickness of the barrier layer reduces the available space for copper region
Solution Approach 1:
The patent extracts and removes the diffusion barrier layer from the interconnect structure by switching to graphite as the conductive material. Graphite's inherent structural stability eliminates the need for a separate barrier layer, thus removing the space-consuming element while maintaining diffusion prevention.
Solution Approach 2:
Graphite inherently provides its own diffusion barrier properties through its stable crystalline structure. The material self-services by preventing diffusion without requiring an additional barrier layer, thus eliminating the trade-off between barrier thickness and conductor thickness.
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
This approach allows for the formation of interconnect structures with smaller dimensions without increased resistivity, advancing the scaling of integrated circuits and eliminating the need for barrier layers, thus improving the performance and efficiency of interconnects.
Implementation Method 1
a graphite layer is deposited
Implementation Method 2
A spacer layer may be deposited on the graphite conductive features to prevent peeling from occurring
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.