Self Aligned Via Fuse for Semiconductor Interconnects
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Solution Overview
Problem
Current semiconductor manufacturing processes for forming electronic fuses are inefficient, as they require separate process flows and result in high programming currents and long programming times, which increase manufacturing costs and reduce chip yield.
Innovation Solution
A self-aligned via process flow is used to form a conductive bridge between two adjacent metal lines of the same metal level, allowing for the creation of an electronic fuse that can be fabricated during normal interconnect process flows, reducing processing costs and enabling faster programming at lower currents.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If separate process flows are used for forming electronic fuses, then manufacturing precision can be maintained, but processing costs increase and productivity decreases
Solution Approach 1:
The patent merges the e-fuse formation process with the normal interconnect process flow by using the same self-aligned via process. The conductive bridge is formed as part of the standard via formation sequence, eliminating the need for separate e-fuse fabrication steps and integrating fuse creation into the existing manufacturing workflow.
Solution Approach 2:
The self-aligned via process is made universal by applying it to both standard interconnect formation and e-fuse creation. The same process steps and materials are used for both purposes, allowing the manufacturing system to handle multiple functions without requiring dedicated specialized processes.
2Reliability
If high programming currents are used to blow fuses, then reliable open circuit creation is achieved, but programming time increases and energy consumption rises
Solution Approach 1:
The conductive bridge is designed with locally optimized properties - it has a reduced vertical thickness compared to the metal lines, creating a specific geometric configuration. This local structural variation concentrates the current density precisely where needed in the bridge region, enabling reliable fuse blowing with lower overall programming currents and reduced programming time.
3Manufacturing precision
If traditional fuse formation processes are used, then manufacturing precision is maintained, but device complexity increases due to separate process flows
Solution Approach 1:
The patent combines multiple process functions into a single integrated process flow. The self-aligned via formation process simultaneously creates both interconnect structures and e-fuse elements, eliminating the need for separate e-fuse fabrication sequences and reducing overall process complexity while maintaining alignment precision.
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 processing costs and enables efficient e-fuse programming with low currents and short programming times, improving chip yield and customization options by forming a conductive bridge that experiences increased current density and heating, facilitating faster e-fuse programming.
Implementation Method 1
a conductive bridge that experiences increased current density and heating, facilitating faster e-fuse programming
Implementation Method 2
electromigration can be defined as 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. In e-fuses that take advantage of electromigration effect, such transport of material caused by the gradual movement of ions can produce voids which cause the e-fuse to blow and create the open circuit.
Data Source
AI summary
A method including forming a first via opening in a substrate, the first via opening is self-aligned to a first trench in the substrate, forming a second via opening in the substrate, the second via opening is self-aligned to a second trench in the substrate, a portion of the second via opening overlaps a portion of the first via opening to form an overlap region, and the overlap region having a width (w) equal to or greater than a space (s) between the first trench and the second trench, and removing a portion of the substrate in the overlap region to form a bridge opening, the bridge opening is adjacent to the first and second via openings and extends between the first and second trenches.