Vertical Contact Fuse Link for Low Voltage Programming
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Solution Overview
Problem
Conventional electrically programmable fuses in semiconductor ICs require high programming voltages and face reliability issues due to narrow fuse link widths, making them difficult to manufacture reproducibly and operate efficiently, especially at reduced power supply voltages.
Innovation Solution
A programmable fuse structure with a single contact fuse link oriented perpendicular to the nodes, surrounded by multiple contacts, and a dielectric layer for electrical isolation, which increases current crowding and electromigration effects, allowing for lower programming voltages and improved reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional e-fuse structure with silicided polysilicon layer is used, then programming is achieved through electromigration, but high programming voltages are required and manufacturing reproducibility is difficult
Solution Approach 1:
The fuse link is reoriented from a planar configuration to a vertical configuration extending through multiple layers (from first node in upper layer through intermediate layer to second node in lower layer). This dimensional change allows the fuse link to achieve sufficient length for reliable electromigration while maintaining manufacturable width dimensions, resolving the contradiction between programming reliability and manufacturing precision.
Solution Approach 2:
The fuse structure is segmented into distinct functional layers: upper node region, fuse link region, intermediate layer with contacts, and lower node region. This segmentation allows each portion to be optimized independently - the fuse link for reliable breakdown and the contacts for current distribution - thereby improving both programming reliability and manufacturing precision.
2Use of energy by moving object
If narrow fuse link width is used to enable programming at lower voltages, then programming voltage is reduced, but manufacturing reproducibility becomes difficult
Solution Approach 1:
The fuse link transitions from a narrow planar trace to a vertical structure spanning multiple layers. This allows the effective programming path length to increase while the lateral width remains manufacturable, enabling lower programming voltages without sacrificing manufacturing reproducibility.
Solution Approach 2:
The invention changes the geometric parameters of the fuse link from lateral dimensions to vertical dimensions. By increasing the length parameter in the vertical direction while controlling the width parameter at manufacturable levels, the structure achieves lower programming voltage requirements while maintaining manufacturing precision.
3Reliability
If higher current density is applied to induce electromigration, then programming is achieved, but significant programming voltages are required
Solution Approach 1:
The vertical orientation of the fuse link through multiple layers increases the effective path length for electromigration. This allows sufficient current density to be achieved over a longer path, producing reliable electromigration effects while distributing the voltage requirement across the vertical structure rather than requiring high voltage across a narrow lateral dimension.
Solution Approach 2:
The intermediate layer with surrounding contacts acts as a mediator that distributes current uniformly to the fuse link. This current distribution mechanism enhances the electromigration effect by ensuring uniform current density along the fuse link, achieving reliable programming at reduced voltage levels.
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
The design enables programming at reduced voltages, enhances electromigration effects, and improves the reproducibility of fuse link breakdown, suitable for ICs operating at lower power supply voltages, such as 1.5V, while maintaining reliable operation.
Implementation Method 1
Electromigration refers to the transportation of material by the gradual movement of ions in a conductor due to the momentum transfer between conducting electrons and diffusing metal atoms.
Implementation Method 2
a dielectric layer underlying the conductive layer that electrically isolates the conductive layer from other devices on the IC
Data Source
AI summary
A fuse structure for a semiconductor integrated circuit (IC) can include a first node comprising a region of a metal layer of an IC manufacturing process and a second node comprising a region of a conductive layer residing on a layer of the IC manufacturing process below the metal layer of the first node. The fuse structure can include a fuse link comprising a conductive material, positioned substantially perpendicular to each of the metal and conductive layers. An upper end of the fuse link couples to the first node and a lower end of the fuse link, that is distal to the upper end, couples to the second node.