Multi-Layer Copper Interconnect Barrier for Electromigration Resistance
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Solution Overview
Problem
Copper interconnects in semiconductor devices suffer from high diffusivity in dielectric materials, leading to copper electromigration and subsequent electrical failures due to corrosion and delamination.
Innovation Solution
A multi-layer barrier structure comprising TiN, TaN, and cobalt oxide layers is used to encapsulate copper interconnects, preventing diffusion into surrounding dielectric materials and enhancing electromigration resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If copper is used for interconnects, then electrical conductivity is improved, but copper diffusion into dielectric materials occurs causing corrosion and delamination
Solution Approach 1:
The barrier structure is divided into multiple distinct layers (first barrier layer, second barrier layer, and optional third barrier layer) with different materials and functions. The first barrier layer (TiN or TaN) provides initial diffusion protection, the second barrier layer (oxide) provides additional diffusion barrier and stress management, and the third barrier layer (TiN or TaN) provides final diffusion protection at the dielectric interface. This segmentation allows each layer to be optimized for specific protective functions against copper diffusion.
Solution Approach 2:
The invention uses a composite barrier structure combining different materials (transition metal nitrides TiN/TaN and their oxides) in a multi-layer configuration. Each material contributes different properties: the nitride layers provide excellent copper diffusion barrier properties, while the oxide layers provide additional barrier functionality and stress management. This composite approach creates a more effective overall barrier than any single material could provide alone.
2Reliability
If a single-layer barrier is used, then manufacturing complexity is reduced, but electromigration resistance is insufficient
Solution Approach 1:
The barrier is segmented into multiple functional layers rather than using a single layer. The first barrier layer (TiN or TaN, 5-20 nm) provides initial copper diffusion protection, the second barrier layer (oxide, 5-20 nm) provides additional barrier functionality and stress management, and the third barrier layer (TiN or TaN, 5-20 nm) provides final diffusion protection at the dielectric interface. This segmentation enables each layer to contribute to electromigration resistance while maintaining manageable manufacturing complexity through standardized deposition processes.
Solution Approach 2:
Different regions of the barrier structure have different material compositions and thicknesses optimized for local requirements. The nitride layers are positioned where copper diffusion risk is highest, while oxide layers are placed for stress management and additional barrier functionality. This local optimization of material properties throughout the barrier structure enhances overall electromigration resistance without requiring uniform complexity throughout.
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 multi-layer barrier effectively suppresses copper electromigration, improving the reliability and longevity of copper interconnects by reducing diffusion and maintaining electrical integrity.
Implementation Method 1
a barrier layer between the conductive structure and the second dielectric layer. The barrier layer may include: a first layer, including titanium or tantalum along inner sidewalls of the first dielectric layer and the second dielectric layer; a second layer, being an oxide of titanium or tantalum and over the first layer
Data Source
AI summary
The present disclosure provides a semiconductor structure. The semiconductor structure includes: a substrate; a transistor on the substrate; a first dielectric layer over the transistor; a second dielectric layer over the first dielectric layer; a barrier layer extending from the second dielectric layer to the first dielectric layer; and a conductive structure separated from the second dielectric layer and the first dielectric layer by the barrier layer. The barrier layer includes: a first layer, including titanium or tantalum along inner sidewalls of the first dielectric layer and the second dielectric layer; a second layer, being an oxide of titanium or tantalum and over the first layer; and a third layer, including cobalt and over the second layer.