Programmable E-Fuse Interconnects with Varying Capping Materials
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Solution Overview
Problem
Existing electrical fuses suffer from undesirable hillock formation due to electromigration, which leads to premature failure and is not effectively addressed in current technologies.
Innovation Solution
The use of interconnect structures with varying capping materials at the metal wiring layer interface, providing different electromigration (EM) resistances, allows for the creation of programmable e-fuses that prevent hillock formation by selecting appropriate Cu/capping layer interfaces, such as SiN, Ta, Ru, and combinations of Co(W, P, B), which alter EM resistance and void growth rates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a two-dimensional dog-bone shape fuse structure is used, then the fuse can be electrically blown to open circuit, but hillocks form at the anode end due to electromigration
Solution Approach 1:
The patent applies local quality by creating a three-dimensional fuse structure with varying cross-sectional areas along its length. The fuse element has a narrower middle section and wider end sections, concentrating the electromigration effect in the middle region while protecting the anode end from hillock formation. This local structural variation allows the fuse to open reliably while preventing harmful hillock formation at critical interfaces.
Solution Approach 2:
The patent transitions from a two-dimensional planar fuse structure to a three-dimensional vertical structure extending through multiple interconnect layers. This dimensional change allows the fuse element to span across dielectric layers with different capping materials, utilizing the vertical dimension to control electromigration patterns and prevent hillock formation at the anode interface while maintaining effective fuse opening capability.
2Ease of manufacture
If standard capping materials are used for all interconnect structures, then manufacturing is simplified, but electromigration resistance cannot be optimized for specific fuse applications
Solution Approach 1:
The patent applies parameter changes by selecting specific capping materials with different electromigration resistance properties for different locations in the fuse structure. The middle section is capped with materials having lower EM resistance to facilitate void formation, while the anode end is capped with materials having higher EM resistance to prevent hillock formation. This differential material selection optimizes both fuse reliability and manufacturing feasibility.
Solution Approach 2:
The patent uses composite material structures where different capping materials are applied to different sections of the fuse element. The structure combines materials with contrasting electromigration properties - such as tungsten nitride or tantalum nitride at the anode end with other dielectric materials in the middle section - to create a composite system that simultaneously achieves reliable fuse opening and prevents harmful hillock formation.
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 enables the fabrication of e-fuses with controlled EM resistance, preventing hillock formation and allowing for e-fuses to be programmed to blow at different current levels, reducing processing costs and improving manufacturing efficiency by integrating e-fuse production into standard interconnect processes.
Implementation Method 1
Some electrically blowable fuses take advantage of the electromigration (EM) effect to open an electrical connection. For example, EM is the transport of material caused by the gradual movement of ions in a conductor due to the momentum transfer between conducting electrons and diffusing metal atoms.
Data Source
AI summary
A structure and design structure is provided for interconnect structures containing various capping materials for electrical fuses and other related applications. The structure includes a first interconnect structure having a first interfacial structure and a second interconnect structure adjacent to the first structure. The second interconnect structure has second interfacial structure different from the first interfacial structure.