Self-Alloyed Copper Interconnects for Electromigration Resistance
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Solution Overview
Problem
In semiconductor structures, electromigration poses challenges due to copper diffusion issues in via interconnects and wiring structures, leading to failure modes like via depletion and line depletion, which existing technologies struggle to effectively address.
Innovation Solution
The method involves depositing metal material within openings and on dielectric surfaces, followed by alloying material deposition and diffusion into the metal material to form self-aligned alloyed regions that inhibit electromigration, specifically enhancing the interface strength of copper-lined via interconnects and wiring structures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If alloying material is deposited over the metal material to inhibit electromigration, then electromigration resistance is improved, but manufacturing complexity increases
Solution Approach 1:
The alloying material is selectively deposited only in recessed areas above via interconnects where electromigration is most severe, rather than uniformly across all metal lines. This localized approach provides electromigration protection where needed most while minimizing additional manufacturing complexity and material usage.
Solution Approach 2:
The recessed areas are formed in advance during the dual damascene process before copper deposition, creating pre-defined locations where alloying material will later be deposited. This preliminary structuring enables targeted electromigration protection without requiring complex post-processing steps.
2Reliability
If copper diffusion is slowed down to prevent via depletion, then via interconnect reliability is improved, but wire resistance increases
Solution Approach 1:
The alloying material is confined to recessed areas directly above via interconnects, creating localized barriers that slow copper diffusion at critical via-copper cap interfaces. The bulk of the wide metal lines remains pure copper, maintaining low resistance for current carrying while providing targeted protection against via depletion.
Solution Approach 2:
The metal interconnect structure is segmented into pure copper regions (wide lines for low resistance) and alloyed regions (recessed areas above vias for diffusion control). This segmentation allows each region to be optimized for its specific function: current transport versus electromigration resistance.
3Productivity
If structure size is decreased to improve integration density, then productivity is improved, but electromigration effects worsen
Solution Approach 1:
As structure sizes decrease and current densities increase, electromigration becomes more severe. The invention applies alloying material locally at the most vulnerable points (via-copper cap interfaces) rather than throughout entire interconnect structures. This enables scaling to smaller dimensions while maintaining electromigration resistance through targeted protection at critical interfaces.
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 effectively minimizes electromigration effects by creating self-aligned alloyed regions that strengthen the interface, improving resistance and scalability while maintaining minimal impact on electrical resistance.
Implementation Method 1
The method further includes diffusing the alloying material into the metal material forming alloyed regions self-aligned with the metal filled openings
Data Source
AI summary
Optimized metal wires for resistance or electromigration, methods of manufacturing thereof and design methodologies are disclosed. The method includes depositing metal material within openings and on a surface of dielectric material resulting in metal filled openings and a topography of recessed areas aligned with the metal filled openings. The method further includes depositing an alloying material over the metal material, including within the recessed areas. The method further includes planarizing the metal material, leaving the alloying material within the recessed areas. The method further includes diffusing the alloying material into the metal material forming alloyed regions self-aligned with the metal filled openings.