Series Steering Elements for Nonvolatile Memory Cell Reliability
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Solution Overview
Problem
Conventional nonvolatile memory arrays face challenges in reducing block defects due to manufacturing defects in steering elements, leading to excessive current leakage, which affects the reliability and efficiency of memory cells.
Innovation Solution
The use of at least two two-terminal non-linear steering elements arranged in series with a resistivity switching storage element, where the steering elements can be diodes or MIM/MIIM diodes, and the storage element can be made of materials like carbon nanotubes or metal oxides, to reduce block defects and enhance threshold voltage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a single steering element is used in each memory cell, then the device complexity is low, but the reliability is reduced due to block defects from manufacturing defects causing excessive current leakage
Solution Approach 1:
The single steering element is segmented into multiple steering elements (first and second steering elements) connected in series. This segmentation ensures that if one steering element has a manufacturing defect causing excessive leakage, the other steering element can compensate and limit the current leakage, thereby improving reliability without requiring a complete redesign of the memory cell structure
Solution Approach 2:
The patent applies beforehand cushioning by pre-configuring redundant steering elements in series before any defect occurs. The series connection creates a built-in protective mechanism where the second steering element acts as a cushion against the potential harmful effects of defects in the first steering element, preventing excessive current leakage and block defects from compromising memory cell operation
2Reliability
If multiple steering elements are arranged in series, then the threshold voltage is increased and reliability is improved, but the device complexity increases
Solution Approach 1:
The multiple steering elements serve multiple functions simultaneously: they provide voltage threshold enhancement through their series connection, offer defect tolerance through redundancy, and maintain compatibility with existing memory cell architectures. This multi-functionality justifies the increased complexity by delivering multiple benefits from a single structural modification
3Ease of manufacture
If conventional single-element configuration is used, then the manufacturing process is simple, but block defects occur due to manufacturing defects in steering elements
Solution Approach 1:
The steering element is segmented into multiple series-connected elements, which can be fabricated using extended versions of existing manufacturing processes. The segmentation approach allows standard deposition and patterning techniques to be applied repeatedly to create multiple elements, maintaining ease of manufacture while improving reliability through the redundant configuration that prevents block defects
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 reduces block defects by ensuring that even if one steering element has a defect, the other can limit current leakage, and increases the threshold voltage, thereby improving the reliability and efficiency of the memory cells.
Implementation Method 1
at least two two-terminal non-linear steering elements arranged in series
Implementation Method 2
a resistivity switching storage element arranged in series with the at least two two-terminal non-linear steering elements
Data Source
AI summary
A nonvolatile memory cell including at least two two-terminal non-linear steering elements arranged in series, and a resistivity switching storage element arranged in series with the at least two two-terminal non-linear steering elements. A memory array, comprising a plurality of the nonvolatile memory cells is also described. A method of forming a nonvolatile memory cell is also described.