Silver Interconnects via Copper Displacement for Low RC Delay
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current methods for forming interconnects in semiconductor devices, particularly in the back-end-of-line (BEOL) portion, face challenges in achieving improved electrical conductivity and reliability due to the limitations of copper metallization.
Innovation Solution
A method involving the formation of interconnect openings in a dielectric layer, where a first conductor layer of copper is displaced and replaced with a second conductor layer of silver through an immersion process, leveraging the higher standard reduction potential of silver to enhance conductivity and reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If copper metallization is used in the BEOL portion of interconnect structure, then the interconnect structure can be formed using standard damascene processes, but the electrical conductivity and reliability are limited
Solution Approach 1:
The patent changes the material parameter from copper to silver in the interconnect structure. Silver has higher electrical conductivity and better reliability characteristics compared to copper, directly addressing the limitation of copper metallization while maintaining compatibility with existing damascene fabrication processes
Solution Approach 2:
The patent replicates the successful damascene metallization process structure but substitutes the metal material from copper to silver. This allows the interconnect structure to maintain the proven manufacturing approach while achieving improved electrical performance and reliability through material substitution
2Quantity of substance
If copper is used as the conductor material, then the fabrication process is straightforward, but the electrical resistance is higher and RC delay is increased
Solution Approach 1:
The patent changes the conductor material parameter from copper to silver. Silver has superior electrical conductivity with lower resistivity compared to copper, which directly reduces electrical resistance and RC delay in the interconnect structure, improving signal transmission efficiency
Solution Approach 2:
The patent uses silver, which although more expensive than copper, provides significantly better electrical performance. The improved conductivity reduces energy loss and enhances device performance, justifying the material substitution in high-performance interconnect applications
3Ease of manufacture
If copper metallization is used, then standard fabrication processes can be applied, but diffusion into low-k dielectric materials occurs requiring thicker barrier layers
Solution Approach 1:
The patent changes the metal material parameter from copper to silver. Silver exhibits reduced diffusion into low-k dielectric materials compared to copper, eliminating the need for thick barrier layers and allowing for thinner barrier structures while maintaining process compatibility
Solution Approach 2:
The patent converts the potential harm of metal diffusion into a benefit by selecting silver, which has lower diffusion propensity into dielectric materials. This reduces the harmful diffusion effect while maintaining ease of manufacture through standard fabrication processes
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 resulting interconnects exhibit lower electrical resistance and improved reliability compared to copper-based features, with silver showing better miscibility and reduced diffusion into low-k dielectric materials, allowing for reduced barrier layer thickness and lower RC delay.
Implementation Method 1
forming a second conductor layer inside the interconnect opening by displacing the first metal of the first conductor layer and replacing the first metal with a second metal different from the first metal
Data Source
AI summary
Methods of forming interconnects. An interconnect opening is formed in a dielectric layer. A first conductor layer composed of a first metal is formed in the interconnect opening. A second conductor layer is formed inside the interconnect opening by displacing the first metal of the first conductor layer and replacing the first metal with a second metal different from the first metal.