Via Gouging Feature for Interconnect Mechanical Strength
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Solution Overview
Problem
The existing methods for forming interconnect structures in semiconductor devices using copper damascene and low k dielectric materials suffer from poor mechanical integrity and damage to the dielectric material due to the argon sputtering process, which affects the coverage of the diffusion barrier and leads to high metal-to-metal leakage and reliability issues, especially when using porous ultra-low k dielectric materials.
Innovation Solution
A method is developed where the gouging feature is formed at the bottom of the via opening before creating the line opening, ensuring continuous diffusion barrier coverage without damaging the dielectric material, thereby enhancing the mechanical strength and reliability of the interconnect structure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If argon sputtering technique is used to create via gouging, then mechanical strength of contact stud is increased, but diffusion barrier coverage is removed and dielectric material is damaged
Solution Approach 1:
The patent performs the gouging action preliminarily by forming a recess in the conductive feature before depositing the diffusion barrier layer. This preliminary recess formation allows subsequent barrier deposition to occur on a pre-prepared surface without requiring post-deposition removal or damage-causing processes
Solution Approach 2:
The patent replaces the mechanical argon sputtering process with a deposition-based approach. Instead of using ion bombardment to create the gouging feature, the invention forms the recess through controlled deposition and selective removal processes that do not involve aggressive sputtering, thereby preserving both the barrier coverage and dielectric integrity
2Strength
If via punch-through technique is used to improve mechanical strength, then anchoring area is created, but liner material is removed and dielectric damage occurs
Solution Approach 1:
The gouging feature is formed in advance before the diffusion barrier deposition step. This preliminary formation of the anchoring area in the conductive feature allows the barrier layer to be deposited continuously over the entire surface including the gouged region, eliminating the need for subsequent barrier repair or re-deposition
Solution Approach 2:
The patent introduces an intermediary deposition process that forms the gouging feature through controlled material deposition and removal rather than direct sputtering. This intermediary approach creates the necessary mechanical anchoring while protecting the surrounding dielectric material and ensuring complete barrier coverage
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 results in improved wiring reliability and reduced metal-to-metal leakage by maintaining continuous diffusion barrier coverage and avoiding damage to the dielectric material, thus addressing the mechanical integrity and reliability concerns in semiconductor interconnect structures.
Implementation Method 1
the argon sputtering technique that is used to create via gouging in the prior art not only removes the deposited liner material, e.g., TaN, from the trench (i.e., line opening) bottom, but also damages the low k dielectric material
Data Source
Figure 1A~1B
Figure 1C~1D
Figure 1D
AI summary
An interconnect structure including a gouging feature at the bottom of one of the via openings and a method of forming the same are provided. In accordance with the present invention, the method of forming the interconnect structure does not disrupt the coverage of the deposited diffusion barrier in the overlying line opening, nor does it introduce damages caused by Ar sputtering into the dielectric material including the via and line openings. In accordance with the present invention, such an interconnect structure contains a diffusion barrier layer only within the via opening, but not in the overlying line opening. This feature enhances both mechanical strength and diffusion property around the via opening areas without decreasing volume fraction of conductor inside the line openings. In accordance with the present invention, such an interconnect structure is achieved by providing the gouging feature in the bottom of the via opening prior to formation of the line opening and deposition of the diffusion barrier in said line opening.