Vertical Anti-Fuse Pillar Geometry for Controlled Breakdown
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Solution Overview
Problem
Existing anti-fuse structures in semiconductor integrated circuits face challenges in ensuring consistent and controlled dielectric breakdown for programming, particularly in field programmable gate arrays and programmable read-only memories, due to variations in material composition and structural design.
Innovation Solution
A vertical anti-fuse structure is designed with specific geometric configurations, including wider bottom portions and closer horizontal distances between metal pillars, embedded in different dielectric layers with varying etch selectivity, and lined with conductive materials to facilitate controlled dielectric breakdown.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the metal pillars are made with uniform width throughout their length, then the manufacturing process is simpler, but the dielectric breakdown cannot be reliably controlled during programming
Solution Approach 1:
The patent applies asymmetry by designing metal pillars with non-uniform cross-sections, where the bottom portions have different widths than the top portions. This asymmetric geometry creates controlled electric field distribution that ensures reliable dielectric breakdown at specific locations during programming, resolving the contradiction between breakdown control and structural simplicity.
Solution Approach 2:
The patent implements local quality by varying the width of metal pillars at different locations - wider at the bottom and narrower at the top. This local geometric variation creates specific electric field concentrations at the bottom portions, enabling controlled dielectric breakdown in the fuse dielectric while maintaining overall structural integrity.
2Reliability
If the bottom portions of metal pillars are made wider, then the electric field concentration and dielectric breakdown control is improved, but the horizontal space required increases
Solution Approach 1:
The patent resolves the space conflict by transitioning from a two-dimensional uniform cross-section to a three-dimensional varying cross-section. The metal pillars have wider bottoms and narrower tops, utilizing the vertical dimension to achieve electric field concentration without proportionally increasing the horizontal footprint, thus maintaining compact device layout.
3Manufacturing precision
If different dielectric layers with varying etch selectivity are used, then the formation of expanded openings is more precise, but the manufacturing process becomes more complex
Solution Approach 1:
The patent applies parameter changes by utilizing dielectric layers with different etch selectivity ratios. This allows the lower dielectric layer to be selectively removed to create expanded openings while leaving the upper dielectric layer intact, enabling precise control of opening geometry through material parameter selection rather than complex process 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
The proposed structure ensures reliable and controlled dielectric breakdown during programming, enhancing the connectivity and functionality of semiconductor devices by ensuring consistent conductive pathways formation.
Implementation Method 1
After the programing, due to dielectric breakdown, the anti-fuse structure becomes conductive connecting devices and/or circuits at, for example, the top and the bottom of the anti-fuse structure together
Data Source
AI summary
Embodiments of present invention provide an anti-fuse structure. The structure includes a first vertical metal pillar having a first bottom portion and a first top portion; a second vertical metal pillar having a second bottom portion and a second top portion; and a fuse dielectric between the first bottom portion of the first vertical metal pillar and the second bottom portion of the second vertical metal pillar, where a width of the first bottom portion of the first vertical metal pillar is wider than a width of the first top portion of the first vertical metal pillar or a width of the second bottom portion of the second vertical metal pillar is wider than a width of the second top portion of the second vertical metal pillar. A method of forming the same is also provided.