Anti-fuse Cell Segmentation for Reliability
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Solution Overview
Problem
Anti-fuse elements in microelectronic devices, particularly those formed by MOSFETs, are prone to reliability issues due to device tuning and breakdown paths, leading to resistance variations and degraded read margins.
Innovation Solution
The design incorporates anti-fuse cells with a control device and anti-fuse elements featuring a top and bottom conductive layer with a dielectric layer in between, where the anti-fuse element is physically stacked upon a lower-level conductive layer, reducing resistance and improving current flow, and multiple anti-fuse elements are arranged in parallel to enhance programming yield.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If anti-fuse element is formed by MOSFET, then device can be manufactured using standard processes, but reliability is reduced due to device tuning sensitivity and breakdown paths
Solution Approach 1:
The anti-fuse element is segmented into separate components: a control device (MOSFET) and an anti-fuse structure with conductive layers and dielectric material. This segmentation allows the control device to be manufactured using standard processes while the anti-fuse structure can be optimized for reliability, resolving the contradiction between ease of manufacture and reliability.
Solution Approach 2:
An intermediary anti-fuse structure is introduced between the control device and the programming circuitry. This structure includes a first conductive layer, second conductive layer, and dielectric layer that mediates the electrical connection, providing a controlled breakdown path that improves reliability while maintaining manufacturability through standard integration processes.
2Device complexity
If MOSFET anti-fuse element is used, then manufacturing is simplified, but breakdown paths from gate to channel or drain cause larger resistance variation and degraded read margin
Solution Approach 1:
The breakdown path problem is extracted from the MOSFET structure by separating the anti-fuse function from the transistor structure. The anti-fuse element uses a dedicated dielectric layer between conductive layers that breaks down in a controlled manner, eliminating the unwanted breakdown paths from gate to channel or drain that occur in MOSFET-based anti-fuse elements.
Solution Approach 2:
The dielectric layer in the anti-fuse structure is designed to be a disposable element that breaks down during programming to create a permanent conductive path. This controlled breakdown provides precise resistance control without the variability issues of MOSFET breakdown paths, while the overall structure remains simple to manufacture.
3Ease of manufacture
If anti-fuse element uses standard MOSFET structure, then manufacturing process is easier, but operation margin is reduced due to device tuning sensitivity
Solution Approach 1:
The anti-fuse structure implements local quality by using specific materials and configurations in different regions: a dielectric layer with controlled breakdown characteristics between conductive layers, and a control device with specific doping profiles. This localized optimization provides both ease of manufacture through standard processes and improved operation margin through tailored local properties.
Solution Approach 2:
The anti-fuse element uses composite materials including dielectric layers, conductive layers, and doped semiconductor regions. This composite structure combines the manufacturing advantages of standard semiconductor materials with the reliability and operation margin benefits of carefully engineered material combinations, resolving the contradiction between process simplicity and adaptability.
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 configuration enhances the reliability and operation margin of anti-fuse cells by reducing resistance variations and improving current flow, thereby increasing the read margin and programming efficiency.
Implementation Method 1
The anti-fuse element includes a first conductive layer, a second conductive layer and a dielectric layer, wherein the dielectric layer is disposed between the first conductive layer and the second conductive layer
Implementation Method 2
An anti-fuse or an anti-fuse element is an electrical device that is designed to create a permanent electrically conductive path in a microelectronic device. Typically, when a voltage across the anti-fuse exceeds a certain level, the permanent electrically conductive path is created.
Data Source
AI summary
An anti-fuse cell includes a control device and an anti-fuse element is introduced. The control device includes a source node, a drain node and a gate node, wherein the gate node is electrically coupled to a word line and the drain node is electrically coupled to a bit line. The anti-fuse element includes a first conductive layer, a second conductive layer and a dielectric layer, wherein the dielectric layer is disposed between the first conductive layer and the second conductive layer. The second conductive layer of the anti-fuse element physically stacks upon and directly contacts a metal layer that is electrically connected to the source node of the control device, and first conductive layer is electrically coupled to a program line through a via. An anti-fuse cell having multiple anti-fuse elements and a chip having a plurality of anti-fuse cells are also introduced.