Cobalt Interconnect Structure With Mn Adhesion for Low-Resistance Reliability
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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 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 resistance to electromigration, mitigating the resistance issues of traditional barrier layers and copper interconnects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If copper interconnects are used, then electrical resistivity is low, but susceptibility to electromigration increases leading to void formation and failure
Solution Approach 1:
The patent introduces cobalt as an intermediary material between the copper interconnect and the barrier layer. This cobalt layer serves as a mediator that prevents direct interaction between copper and the barrier layer, thereby eliminating electromigration effects while maintaining low electrical resistivity. The cobalt layer acts as a protective interface that resolves the contradiction between copper's low resistivity and its susceptibility to electromigration.
Solution Approach 2:
The patent creates a composite interconnect structure consisting of multiple layers: copper interconnect, cobalt barrier layer, and manganese adhesion layer. This composite structure combines the advantages of different materials - copper provides low electrical resistivity, cobalt provides resistance to electromigration, and manganese provides adhesion. The composite material approach resolves the technical contradiction by integrating multiple materials with complementary properties.
2Reliability
If tungsten metallization is used, then resistance to electromigration is high, but electrical resistivity increases degrading IC performance
Solution Approach 1:
The patent uses cobalt as an intermediary layer that provides electromigration resistance without the high electrical resistivity of tungsten. The cobalt layer mediates between the requirement for electromigration resistance and the need for low electrical resistivity, achieving both goals simultaneously. This intermediary approach allows the system to benefit from cobalt's favorable electrical properties while gaining protection against electromigration.
Solution Approach 2:
The patent changes the material parameter from tungsten (high resistivity, high electromigration resistance) to cobalt (low resistivity, high electromigration resistance). This parameter change optimizes the interconnect properties by selecting a material with superior electrical conductivity while maintaining resistance to electromigration, thereby degrading IC performance is avoided.
3Reliability
If traditional barrier layers are used with copper interconnects, then electromigration is resisted, but electrical resistance increases
Solution Approach 1:
The patent introduces cobalt as an intermediary barrier layer that replaces traditional barrier materials. This cobalt layer provides electromigration resistance while maintaining low electrical resistance due to its superior electrical conductivity compared to traditional barriers. The cobalt intermediary resolves the contradiction by providing barrier functionality without the penalty of high electrical resistance.
Solution Approach 2:
The patent changes the barrier layer material parameters from traditional high-resistivity materials to cobalt with its favorable electrical properties. This parameter change reduces the electrical resistance of the barrier layer while maintaining its electromigration resistance function, thereby reducing energy loss in the interconnect structure.
4Manufacturing precision
If manganese adhesion layer is added to improve gap filling, then adhesion and wetting are enhanced, but device complexity increases
Solution Approach 1:
The patent introduces manganese as an intermediary adhesion layer between the cobalt barrier layer and the underlying substrate. This thin manganese layer serves as a mediator that enhances adhesion and wetting properties, enabling robust gap filling. The addition of this single intermediary layer significantly improves manufacturing precision with minimal increase in overall device complexity.
Solution Approach 2:
The patent changes the surface properties of the interconnect structure by adding the manganese adhesion layer. This layer modifies the wetting and adhesion parameters, enabling better gap filling during fabrication. The parameter change in surface properties achieves improved manufacturing precision without substantially increasing device complexity.
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
Cobalt interconnects with manganese-based adhesion layers achieve robust gap filling and low resistance, enhancing the performance of interconnect structures by reducing electromigration effects and electrical resistivity.
Implementation Method 1
an adhesive layer, comprising manganese, disposed over the conductive region and on the sidewalls
Implementation Method 2
The Mn based layer also provides wetting to the cobalt metal
Implementation Method 3
a fill material, comprising cobalt, within the opening and on a surface of the adhesion layer
Implementation Method 4
Cobalt interconnects with manganese-based adhesion layers achieve robust gap filling and low resistance, enhancing the performance of interconnect structures by reducing electromigration effects and electrical resistivity
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.