Copper Interconnect Structure Without TaN Barriers
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Solution Overview
Problem
The increasing complexity and scaling of semiconductor integrated circuits (ICs) lead to challenges with copper interconnect structures, including high resistivity due to the use of barrier metals like tantalum nitride (TaN), which reduce the available space for copper lines and increase RC delay, while current copper diffusion barriers are not effective in preventing copper diffusion without compromising dielectric integrity.
Innovation Solution
A copper interconnect structure is developed without barrier metals, using a protective dielectric layer that acts as both a low-k dielectric and copper diffusion barrier, formed between copper lines and low-k dielectric layers, and enclosed by protective dielectric structures to prevent copper diffusion and reduce resistivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If barrier metals like tantalum nitride (TaN) are used to prevent copper diffusion, then copper diffusion is blocked, but the available space for copper lines is reduced and resistivity increases
Solution Approach 1:
The patent removes the traditional barrier metal layer (TaN) from the interconnect structure and replaces it with a dielectric liner that provides diffusion barrier functionality. This extraction of the barrier metal function allows for increased copper line width while maintaining diffusion prevention through the dielectric material's inherent barrier properties.
Solution Approach 2:
The dielectric layer is designed to serve multiple functions: it acts as the primary dielectric medium for insulation, provides copper diffusion barrier functionality through its material composition, and serves as the liner for the copper interconnect structure. This multi-functionality eliminates the need for separate barrier metal layers.
2Reliability
If barrier metals like tantalum nitride (TaN) are used to prevent copper diffusion, then copper diffusion is blocked, but RC delay increases due to reduced copper line space
Solution Approach 1:
By removing the barrier metal layer and relying on the dielectric material's inherent barrier properties, the patent increases the effective copper line width. This increased width reduces resistance, thereby reducing RC delay while maintaining diffusion prevention through the dielectric liner.
3Reliability
If traditional copper diffusion barriers are used, then copper diffusion is prevented, but dielectric integrity is compromised
Solution Approach 1:
The patent employs a composite dielectric structure consisting of multiple dielectric layers with different properties. The first dielectric layer provides the primary diffusion barrier, while the second dielectric layer with lower k-value provides insulation and maintains dielectric integrity. This composite approach achieves both diffusion prevention and dielectric stability.
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
This approach maintains the available space for copper lines, reduces resistivity, and minimizes etching damage to the low-k dielectric, thereby improving the performance and reducing RC delay in semiconductor devices.
Implementation Method 1
a protective dielectric layer that acts as both a low-k dielectric and copper diffusion barrier
Data Source
AI summary
A semiconductor structure comprises: a base semiconductor structure having a top dielectric layer and at least one metal contact structure disposed in the top dielectric layer; and a patterned dielectric layer disposed on the top dielectric layer. The patterned dielectric layer comprises: a plurality of enclosed protective dielectric structures separated by gap regions, each enclosed protective dielectric structure comprising: a dielectric core; and a protective dielectric enclosure enclosing the dielectric core on all sides of the dielectric core; and a plurality of metal interconnect structures disposed in the gap regions in the patterned dielectric layer and in contact with the plurality of enclosed protective dielectric structures, each of the plurality of metal interconnect structures consisting of a metal interconnect material. A top surface of each of the plurality of metal interconnect structures is exposed and substantially coplanar with a top surface of the protective dielectric enclosure.