Discontinuous Noble Metal Cap for Interconnect EM Resistance
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Solution Overview
Problem
Semiconductor interconnect structures face challenges with electromigration (EM) resistance without degrading time-dependent dielectric breakdown reliability, particularly due to issues with metal cap deposition causing electrical shorts and high process costs, as well as corrosion during cleaning processes.
Innovation Solution
The implementation of a discontinuous or non-uniform noble metal-containing cap on the surface of conductive materials embedded within a low k dielectric material, which prevents metal cap residues from forming on the dielectric surface and does not extend onto the diffusion barrier, thereby enhancing EM resistance and maintaining TDDB reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a continuous metal cap is deposited on the conductive material surface, then electromigration resistance is improved, but metal cap residues extend onto the dielectric surface causing electrical shorts
Solution Approach 1:
The patent applies local quality by making the metal cap discontinuous rather than continuous. The cap is present only at specific locations (corners and edges) where electromigration stress is highest, rather than covering the entire conductive material surface. This localized approach provides EM protection where needed while eliminating residues that would cause shorts in low-k dielectric regions.
Solution Approach 2:
The metal cap is segmented into discrete regions rather than forming a continuous layer. The cap is divided into multiple separate cap regions located at corners and edges of the conductive material, which prevents formation of continuous metal pathways that could bridge to adjacent conductors and cause electrical shorts.
2Reliability
If a metal cap is deposited to enhance EM resistance, then reliability is improved, but process cost increases
Solution Approach 1:
The patent uses partial action by depositing metal cap only where absolutely necessary (corners and edges) rather than providing complete coverage. This partial capping approach provides sufficient EM protection to achieve reliability goals while minimizing the amount of metal material used and reducing process complexity and cost.
3Reliability
If a metal cap is deposited on the conductive material, then EM resistance is improved, but corrosion occurs during cleaning processes
Solution Approach 1:
By limiting the metal cap to discrete locations (corners and edges) rather than continuous coverage, the patent reduces the total surface area exposed to corrosive cleaning chemicals. This localized approach maintains EM protection functionality while minimizing corrosion risk during subsequent processing steps.
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 significantly improves EM resistance and maintains the reliability of time-dependent dielectric breakdown, reducing the risk of electrical shorts and process costs while preventing corrosion, thus enhancing the overall performance and extendibility of semiconductor interconnect structures.
Implementation Method 1
a noble metal-containing cap present at least on some portion of the upper surface of the at least one conductive material... enhancing EM resistance
Data Source
AI summary
An interconnect structure including a noble metal-containing cap that is present at least on some portion of an upper surface of at least one conductive material that is embedded within an interconnect dielectric material is provided. In one embodiment, the noble metal-containing cap is discontinuous, e.g., exists as nuclei or islands on the surface of the at least one conductive material. In another embodiment, the noble metal-containing cap has a non-uniform thickness across the surface of the at least one conductive material.