Copper Interconnect Liner Sidewall Projections Electromigration
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Solution Overview
Problem
Conventional copper-based BEOL interconnect structures are prone to electromigration, leading to metal contamination and dielectric breakdown due to copper migration along interfaces, which compromises the integrity of insulating layers and increases signal propagation delay.
Innovation Solution
The implementation of a conductive liner layer between the insulating layer and the conductive feature with sidewall portions projecting above the top surface of the insulating layer, combined with a capping layer on the conductive feature, reduces electromigration by eliminating planar interfaces susceptible to copper diffusion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If copper metal is used in interconnect structures to reduce resistance, then signal propagation delay is reduced, but electromigration causes copper to migrate along interfaces leading to metal contamination and dielectric breakdown
Solution Approach 1:
A liner layer is introduced as an intermediary between the copper conductive feature and the dielectric material. This liner layer prevents direct contact and interaction between copper and dielectric, thereby blocking copper migration and contamination while maintaining the electrical performance benefits of copper interconnects.
Solution Approach 2:
The liner layer is configured to extend beyond the dielectric surface, creating a self-protecting structure where the liner material itself serves as both the diffusion barrier and the structural element that prevents copper migration along the interface.
2Object-affected harmful factors
If conventional liner configurations are used, then copper isolation from dielectric is achieved, but planar interfaces remain susceptible to copper diffusion during electromigration
Solution Approach 1:
The liner layer is configured with a non-planar geometry that extends beyond the dielectric surface, eliminating the flat interface that is susceptible to copper diffusion. This curved or protruding configuration disrupts the migration path of copper atoms during electromigration events.
3Object-affected harmful factors
If copper migration is prevented, then dielectric integrity is maintained, but signal propagation delay increases due to higher resistance
Solution Approach 1:
The liner layer acts as a thin intermediary that provides diffusion barrier functionality while maintaining minimal thickness to preserve electrical performance. This allows copper interconnects to maintain low resistance for fast signal propagation while the liner prevents catastrophic dielectric breakdown from copper migration.
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 configuration enhances electromigration resistance, maintaining the integrity of insulating layers and reducing signal propagation delay, thereby improving the reliability and performance of copper-based interconnect structures.
Implementation Method 1
a conductive liner layer disposed between the insulating layer and the conductive feature along at least the sidewalls of the opening
Implementation Method 2
The conductive liner layer has sidewall portions that project above the top surface of the insulating layer adjacent to the sidewalls of the opening
Data Source
AI summary
Design structure embodied in a machine readable medium for designing, manufacturing, or testing a design. The design structure comprises an insulating layer of a dielectric material, an opening having sidewalls extending from a top surface of the insulating layer toward a bottom surface of the insulating layer, and a conductive feature disposed in the opening. The design structure includes a top capping layer disposed on at least a top surface of the conductive feature and a conductive liner layer disposed between the insulating layer and the conductive feature along at least the sidewalls of the opening. The conductive liner layer of the design structure has sidewall portions that project above the top surface of the insulating layer adjacent to the sidewalls of the opening.