Soluble Self-Aligned Barrier for Interconnect Resistivity
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Solution Overview
Problem
The challenge in semiconductor interconnect structures is to minimize the thickness of copper diffusion and protection barrier layers while maintaining their functionality, as they contribute significantly to the overall resistivity of the interconnect structure, especially at smaller technology nodes, where controlling the uniformity and conformality of thin metal barrier deposition is difficult.
Innovation Solution
A self-aligned barrier layer is formed by depositing a dissolvable reaction material within trenches or vias, which converts into a dense barrier layer upon annealing, allowing the interconnect material to react and form a copper alloy with reduced resistivity, thereby minimizing the need for additional barrier layers and enhancing deposition control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a copper diffusion and protection barrier layer (such as TaN) is deposited to prevent copper diffusion, then the barrier functionality is improved, but the overall resistivity of the interconnect structure increases due to the higher resistance of the liner material
Solution Approach 1:
The patent removes the traditional TaN barrier layer entirely and replaces it with a copper alloy interconnect material that inherently prevents copper diffusion through its compositional design. The alloy contains elements like silicon that form diffusion barriers at the interface with the dielectric, eliminating the need for a separate TaN liner while maintaining low resistivity.
Solution Approach 2:
The patent uses a composite copper alloy material containing copper and other elements (such as silicon, carbon, or nitrogen) that combines the low resistivity of copper with diffusion barrier properties. This composite approach allows the interconnect material itself to serve both as conductor and diffusion barrier, resolving the contradiction between conductivity and barrier functionality.
2Object-affected harmful factors
If the liner material thickness is reduced to minimize resistivity impact, then the interconnect resistivity is improved, but the barrier and lining functionality cannot be maintained
Solution Approach 1:
The patent eliminates the separate barrier liner layer and integrates barrier functionality directly into the copper alloy interconnect material. By using an alloy with inherent diffusion barrier properties, the design removes the need for a thin liner that would compromise barrier functionality while maintaining low resistivity.
Solution Approach 2:
The copper alloy interconnect material combines conductive copper with barrier-forming elements, creating a single material that simultaneously provides both low resistivity and effective diffusion barrier functionality, eliminating the trade-off between thickness and functionality.
3Manufacturing precision
If advanced techniques such as atomic layer deposition (ALD) are used to deposit thin metal barrier layers, then the manufacturing precision is improved, but it remains difficult to control the uniformity, conformality, and integrity of such thin metal barrier deposition
Solution Approach 1:
The patent removes the complex multi-step process of depositing and controlling ultra-thin barrier layers entirely. Instead, it uses a simpler approach where the copper alloy material is deposited and then annealed to form the barrier, eliminating the manufacturing challenges associated with precise thin film deposition control.
Solution Approach 2:
The patent changes the deposition parameters by using a thicker copper alloy layer that is subsequently annealed at elevated temperatures. This parameter change transforms the material properties during annealing to form a dense, continuous barrier layer, avoiding the need for precise control of ultra-thin deposition parameters.
4Length of moving object
If the trench and via sizes continue to shrink, then the device scaling is improved, but the barrier and seed layers must be only several nanometers thick, making deposition control even more difficult
Solution Approach 1:
The patent eliminates the separate seed layer requirement by using the copper alloy material that can be directly deposited and annealed to form both the interconnect and the barrier. This removes the need for precise deposition of multiple ultra-thin layers in shrinking features.
Solution Approach 2:
The patent changes the deposition thickness parameters to use a thicker copper alloy layer (several nanometers to tens of nanometers) that is subsequently annealed. This parameter change provides sufficient material to form a continuous barrier after annealing, even in shrunk features, without requiring ultra-precise control of ultra-thin deposition.
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 reduces the overall resistivity of the interconnect structure, prevents copper diffusion, and allows for effective use in smaller technology nodes by forming a dense, continuous barrier layer that dissolves into the copper matrix, resulting in a lower resistivity alloy interconnect material.
Implementation Method 1
annealing a portion of the dissolvable reaction material to a self-forming barrier layer
Implementation Method 2
allowing the interconnect material to react and form a copper alloy with reduced resistivity
Data Source
AI summary
The present disclosure relates to semiconductor structures and, more particularly, to a soluble self-aligned barrier first for interconnect structure and methods of manufacture. The structure includes: a self-aligning barrier layer lining a trench of an interconnect structure; and an alloy interconnect material over the self-aligned barrier layer. The alloy interconnect material is an alloy composed of metal interconnect material and pre-anneal material that also forms the self-aligning barrier layer.