Cobalt Interconnect Structure With Manganese Adhesion for Electromigration
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Solution Overview
Problem
Copper interconnects in integrated circuits are susceptible to electromigration, leading to void formation and failure, while tungsten interconnects offer resistance to electromigration but have higher electrical resistivity, degrading IC performance.
Innovation Solution
The use of cobalt interconnects with a manganese-based adhesion layer and cobalt fill material, which provides low resistance and high resistance to electromigration, mitigating the issues of conventional copper and tungsten interconnects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If copper interconnects are used, then electrical resistivity is low, but electromigration resistance is poor leading to void formation and failure
Solution Approach 1:
The patent employs a composite interconnect structure consisting of a cobalt-based fill material combined with a manganese-based adhesion layer. This composite approach leverages the low resistivity of cobalt (comparable to copper) while the manganese layer provides enhanced electromigration resistance, thus resolving the contradiction between electrical performance and reliability.
Solution Approach 2:
The patent changes the material composition parameters by transitioning from pure copper to cobalt-based materials with specific compositional ranges (e.g., cobalt content of at least 80 atomic percent). This parameter change enables simultaneous achievement of low electrical resistivity and high electromigration resistance, eliminating the trade-off present in conventional materials.
2Reliability
If tungsten metallization is used, then electromigration resistance is high, but electrical resistivity is 4 to 6 times higher than copper
Solution Approach 1:
The patent uses a composite structure of cobalt fill material with manganese adhesion layer, combining the benefits of different materials. Cobalt provides electrical conductivity comparable to copper, while the manganese layer contributes to electromigration resistance, achieving a balance that neither pure tungsten nor pure copper can accomplish alone.
Solution Approach 2:
The patent applies local quality by using manganese-based adhesion layer specifically at the interfaces where electromigration is most problematic, while the bulk cobalt material maintains low resistivity. This localized approach to material selection optimizes both electrical performance and reliability without the penalties of using tungsten throughout.
Data Source
AI summary
An embodiment includes a metal interconnect structure, comprising: a dielectric layer disposed on a substrate; an opening in the dielectric layer, wherein the opening has sidewalls and exposes a conductive region of at least one of the substrate and an interconnect line; an adhesive layer, comprising manganese, disposed over the conductive region and on the sidewalls; and a fill material, comprising cobalt, within the opening and on a surface of the adhesion layer. Other embodiments are described herein.