Reversible Fuse Structures Using Electromigration for Compact Integration
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Solution Overview
Problem
Current electronic fuse and antifuse structures in semiconductor devices face challenges in increasing current density, leading to high energy consumption and complex design, particularly in minimizing the spacing between fuse elements and neighboring circuitry.
Innovation Solution
The method involves forming reversible fuse and antifuse structures with a damascene or dual damascene line configuration, using materials like Cu, Ru, Ir, and Pt for high conductivity, and insulating materials like SiN and SiO2 to create airgaps and facilitate electromigration, allowing for programmability and reduced heat loss during programming.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If laser ablation is used to program fuse elements, then the programming process is simple, but the spacing between fuse element and neighboring circuitry must be large to avoid collateral damage
Solution Approach 1:
The patent replaces laser ablation (optical/thermal process) with an electromigration-based electrical programming process. This substitution eliminates the need for large clearance spacing while maintaining programming capability, as the electrical process is more localized and controllable compared to laser ablation.
Solution Approach 2:
The patent changes the programming mechanism from thermal/laser-based to electrical current-based, utilizing electromigration parameters. This allows for smaller feature sizes and reduced spacing requirements while achieving the same fuse programming function through material migration driven by high current density.
2Area of stationary object
If electronic fuse with small feature size is used, then spacing to neighboring circuitry is reduced, but design complexity increases particularly in material choice and integration scheme
Solution Approach 1:
The patent merges the fuse element design with standard semiconductor interconnect structures, using the same metal layers and integration schemes already present in the device. This eliminates the need for separate fuse structure designs and material selections, reducing complexity while enabling small feature sizes.
Solution Approach 2:
The fuse element is designed to use the same materials and structures as the surrounding interconnects, making the fuse structure universal and compatible with existing semiconductor manufacturing processes. This multi-functionality approach allows the same layers to serve both interconnect and fuse purposes, simplifying the overall design.
3Reliability
If high current is passed through fuse element for programming, then the fuse material is obliterated creating open state, but energy consumption is high
Solution Approach 1:
The patent converts the potentially harmful effect of high current (which causes complete material obliteration and high energy consumption) into a beneficial electromigration process. By controlling the current to induce material migration rather than complete vaporization, the process achieves reliable programming with reduced energy requirements.
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 enhances programming efficiency by increasing current density and reducing energy consumption while simplifying the design of fuse and antifuse structures, enabling smaller feature sizes and more compact integration without collateral damage.
Implementation Method 1
Yet another type of electronic fuses is based on electromigration. Current crowding takes place around a fixed location thus initiating electromigration which results in further current crowing and material migration along the direction of the electron movement along the fuse element.
Implementation Method 2
During programming, a high electrical current is passed through the electronic fuse element resulting in the fuse element being heated to a very high temperature. Thus the fuse material is obliterated creating an electrically open state.
Data Source
AI summary
A structure and method of fabricating reversible fuse and antifuse structures for semiconductor devices is provided. In one embodiment, the method includes forming at least one line having a via opening for exposing a portion of a plurality of interconnect features; conformally depositing a first material layer over the via opening; depositing a second material layer over the first material layer, wherein the depositing overhangs a portion of the second material layer on a top portion of the via opening; and depositing a blanket layer of insulating material, where the depositing forms a plurality of fuse elements each having an airgap between the insulating material and the second material layer. The method further includes forming a plurality of electroplates in the insulator material connecting the fuse elements. In another embodiment, the method includes depositing a first and a second material layer on a semiconductor substrate, wherein the second material layer having a higher electrical conductivity than the first material layer; selectively etching the first and second material layer to create at least one constricted region to facilitate electromigration of the second material; wherein the electromigration creates a plurality of micro voids; and forming a plurality of electrical contacts on the second material layer.