Dual Damascene Interconnects With Segmented Liners
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Solution Overview
Problem
Advanced dual damascene interconnect structures face a challenge in using alternative metals for enhanced electromigration resistance without increasing via resistance.
Innovation Solution
Incorporating a metallic seed liner with a first bulk resistivity and a first metallic structure with a second bulk resistivity higher than the first within the via portion, and optionally a second metallic structure in the line portion, both embedded in an interconnect dielectric material layer, to achieve enhanced electromigration resistance and controlled via resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If alternative metals such as cobalt or ruthenium are used in the electrically conductive via to enhance electromigration resistance, then electromigration resistance is improved, but via resistance increases significantly
Solution Approach 1:
The via structure is segmented into multiple functional layers: a diffusion barrier liner (TaN) for protection, a metallic seed liner (Cu) for low resistance and electroplating seed, and an alternative metal structure (Co or Ru) for electromigration resistance. Each layer performs a specific function, allowing the system to achieve both low via resistance and high electromigration resistance simultaneously.
Solution Approach 2:
The via is constructed as a composite structure combining multiple materials with complementary properties. The copper seed liner provides excellent electrical conductivity and serves as a plating seed, while the cobalt or ruthenium alternative metal provides enhanced electromigration resistance. This composite approach allows the via to achieve both low resistance and high reliability.
2Reliability
If alternative metals replace copper or copper alloy in the electrically conductive via, then electromigration resistance is enhanced, but manufacturing complexity increases
Solution Approach 1:
The via structure is divided into distinct functional segments: diffusion barrier liner, metallic seed liner, and alternative metal structure. This segmentation allows each material to be optimized for its specific function while maintaining overall manufacturability through standardized deposition and electroplating processes.
Solution Approach 2:
The invention changes the material parameters systematically across different via regions. The diffusion barrier liner uses refractory materials for protection, the seed liner uses copper for low resistance and plating capability, and the alternative metal structure uses cobalt or ruthenium for electromigration resistance. These parameter changes are implemented through controlled deposition thicknesses and electroplating processes.
Data Source
AI summary
Advanced dual damascene interconnects have been provided in which a metallic seed liner composed of an electrically conductive metal or metal alloy having a first bulk resistivity is located on sidewall surfaces and a bottom wall of a first metallic structure that is present in a via portion of a combined via/line opening that is present in an interconnect dielectric material layer. The first metallic structure is composed of an electrically conductive metal or metal alloy that has a second bulk resistivity that is higher than the first bulk resistivity. In some embodiments, a second metal structure is present on a topmost surface of the first metallic structure. The second metallic structure is composed of an electrically conductive metal or metal alloy that differs from the electrically conductive metal or metal alloy of the first metallic structure.