Hybrid Copper Interconnect Structure for Low-Resistivity Narrow Lines
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Solution Overview
Problem
Semiconductor devices face challenges with electromigration resistance due to copper diffusion through grain boundaries in narrow-line polycrystalline microstructures, which worsens with device scaling, and existing interconnect structures do not adequately address this issue.
Innovation Solution
Integrating both narrow-line bamboo microstructures and polycrystalline microstructures within the same metal layer, where the bamboo microstructures reduce grain boundary diffusion and electromigration by having perpendicular grain boundaries, and the polycrystalline microstructures provide high conductivity through larger copper cross-sectional areas.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If device scaling is continued to improve integration density, then productivity is improved, but electromigration resistance deteriorates due to increased copper diffusion through grain boundaries
Solution Approach 1:
The patent changes the microstructural parameters of the copper interconnects by introducing bamboo microstructures with perpendicular grain boundaries. This parameter change (from random polycrystalline grain structure to oriented bamboo structure) fundamentally alters the diffusion pathways for copper atoms, blocking electromigration even as device dimensions continue to scale. The perpendicular grain boundaries act as effective barriers that maintain electromigration resistance despite continued scaling for higher integration density.
2Reliability
If bamboo microstructures with perpendicular grain boundaries are used, then electromigration resistance is improved, but manufacturing complexity increases due to the need for integrated microstructure formation
Solution Approach 1:
The patent merges the formation of bamboo and polycrystalline microstructures into a single integrated process flow within the same metal layer. Rather than requiring separate fabrication steps for different microstructure types, the methodology combines them into one unified approach that forms both microstructure types simultaneously during the copper deposition and annealing process. This merging reduces manufacturing complexity while maintaining the electromigration resistance benefits of bamboo structures.
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 enhances electromigration resistance and conductivity, achieving high reliability and performance by reducing material transport and parasitic crosstalk, with copper resistivity less than 4 microOhm-cm in lines thinner than 100 nm.
Implementation Method 1
annealing the dielectric layer to form the semiconductor device, wherein a narrow-line bamboo microstructure is formed in the second portion of the dielectric layer
Implementation Method 2
plating copper onto the liner material
Data Source
AI summary
A device relates to a semiconductor device. The semiconductor device includes a narrow-line bamboo microstructure integrated within a metal layer of the semiconductor device and a narrow-line polycrystalline microstructure. The narrow-line polycrystalline microstructure is integrated within the same metal layer as the narrow-line bamboo microstructure.