Graded Metallic Liner for Semiconductor Interconnects
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Solution Overview
Problem
The structural integrity and high resistivity of metal interconnect structures in semiconductor devices lead to significant RC delays and voltage drops due to the presence of metallic barrier and adhesion layers, which occupy valuable space and reduce the volume percentage of high conductivity metal fill materials.
Innovation Solution
The use of a graded metallic alloy layer with a gradually decreasing atomic concentration of a diffusion barrier material and a gradually increasing atomic concentration of an adhesion material, replacing the traditional combination of metallic barrier and adhesion layers, to enhance the fractional volume of metallic fill materials and improve electrical conductivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional metallic barrier and adhesion layers are used, then structural integrity is maintained, but electrical conductivity deteriorates due to reduced volume percentage of high conductivity metal fill materials
Solution Approach 1:
The patent combines the diffusion barrier function and adhesion function into a single graded metallic alloy layer. This layer has a composition that varies through its thickness, with the first metallic material concentration decreasing and the second metallic material concentration increasing from the dielectric interface toward the fill material interface, thereby integrating multiple functions into one structure and maximizing the volume available for high conductivity metal fill materials
Solution Approach 2:
The graded metallic alloy layer exhibits spatially varying composition and properties. The first metallic material provides diffusion barrier properties near the dielectric interface, while the second metallic material provides adhesion properties near the fill material interface. This local differentiation of material properties within a single continuous layer maintains both barrier and adhesion functions while optimizing electrical conductivity
2Reliability
If traditional metallic barrier and adhesion layers are used, then diffusion barrier and adhesion properties are provided, but the volume fraction of high conductivity metal is reduced
Solution Approach 1:
The patent merges the traditionally separate barrier layer and adhesion layer into a single graded metallic alloy layer. This integration eliminates the need for multiple discrete layers, thereby maximizing the volume fraction of high conductivity metal fill materials while maintaining both diffusion barrier and adhesion properties through the compositional gradient within the single layer
Solution Approach 2:
The graded metallic alloy layer is a composite material with spatially varying composition. It combines two different metallic materials in a controlled gradient, allowing the layer to exhibit both diffusion barrier characteristics (from the first metallic material near the dielectric) and adhesion characteristics (from the second metallic material near the fill material), thereby achieving multiple functions in a space-efficient manner
Data Source
AI summary
A structure may include an interconnect-level dielectric layer containing a dielectric material and overlying a substrate, and a metal interconnect structure embedded in the interconnect-level dielectric layer and including a graded metallic alloy layer and a metallic fill material portion. The graded metallic alloy layer includes a graded metallic alloy of a first metallic material and a second metallic material. The atomic concentration of the second metallic material increases with a distance from an interface between the graded metallic alloy and the interconnect-level dielectric layer. The graded metallic alloy layer may be formed by simultaneous or cyclical deposition of the first metallic material and the second metallic material. The first metallic material may provide barrier property, and the second metallic material may provide adhesion property.