Binary Metal Liner Layers for Copper Interconnect Adhesion
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Solution Overview
Problem
In microelectronic devices, particularly at the 5 nm node and below, the challenge lies in achieving reliable adhesion between copper interconnects and dielectric barrier layers, with thicker barrier layers increasing resistivity and susceptibility to electro-migration failures, while current methods are limited by single-material intrinsic properties.
Innovation Solution
A two-metal liner film is introduced, comprising two metals such as cobalt and manganese, tantalum, or ruthenium, which can be deposited using atomic layer deposition or chemical vapor deposition, providing improved adhesion and mobility between the barrier layer and gap fill metal, with a thickness of less than 20 Angstroms.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a single-material barrier layer is used to prevent electromigration, then adhesion between copper interconnects and dielectric barrier layers is improved, but resistivity increases and device reliability deteriorates
Solution Approach 1:
The patent employs a composite liner structure consisting of multiple metal layers (e.g., ruthenium and cobalt, or tungsten and cobalt) instead of a single-material liner. This composite approach allows optimization of each layer's thickness and composition to achieve both low resistivity and high adhesion, resolving the contradiction between reliability and material quantity.
Solution Approach 2:
Different metal layers within the liner are assigned different functions: the first metal layer (e.g., ruthenium or tungsten) provides adhesion to the dielectric barrier layer, while the second metal layer (e.g., cobalt) provides low resistivity and copper mobility enhancement. This local functional differentiation resolves the contradiction by optimizing each layer for its specific purpose.
2Strength
If barrier layer thickness is increased to improve adhesion, then adhesion strength is improved, but resistivity increases and electromigration susceptibility worsens
Solution Approach 1:
The composite liner structure allows the total liner thickness to be reduced while maintaining or improving adhesion strength. The first metal layer provides strong adhesion to the dielectric barrier layer, enabling the overall liner to be thinner than traditional single-material liners while achieving equal or better adhesion performance.
Solution Approach 2:
The first metal layer is specifically optimized for adhesion to the dielectric barrier layer, while the second metal layer is optimized for electrical properties. This local optimization allows the adhesion-critical interface to be strengthened without increasing the total liner thickness that would harm electrical performance.
3Ease of operation
If single-material liner thickness is increased to improve metal adhesion and filling mobility, then adhesion and mobility are improved, but resistivity increases and device complexity worsens
Solution Approach 1:
The composite liner structure provides copper filling mobility enhancement without increasing total thickness. The second metal layer (e.g., cobalt) specifically enhances copper mobility during gap fill, while the first metal layer maintains adhesion, achieving the same functional benefits with reduced overall material quantity.
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
The two-metal liner film enhances interfacial adhesion and mobility, reducing electromigration failures and enabling advanced node integration with lower resistivity, while simplifying the integration process by potentially extending metal fill and capping capabilities.
Implementation Method 1
which can be deposited using atomic layer deposition or chemical vapor deposition
Implementation Method 2
which can be deposited using atomic layer deposition or chemical vapor deposition
Data Source
AI summary
Described are microelectronic devices comprising a dielectric layer formed on a substrate, a feature comprising a gap defined in the dielectric layer, a barrier layer on the dielectric layer, a two metal liner film on the barrier layer and a gap fill metal on the two metal liner. Embodiments provide a method of forming a microelectronic device comprising the two metal liner film on the barrier layer.