Variable Resistance Layer Oxygen Gradient for Memory Uniformity
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Solution Overview
Problem
Conventional non-volatile memory devices exhibit non-uniformity in characteristics, leading to increased electric power consumption and read errors due to the correlation between switching and read currents, making it difficult to determine the resistance state accurately.
Innovation Solution
A non-volatile memory element with a variable resistance layer comprising a third metal oxide layer, a second metal oxide layer, and a first metal oxide layer, stacked in order, where the oxygen content atomic percentages satisfy specific ratios, reducing non-uniformity by limiting the extension of oxygen-deficient regions and stabilizing resistance changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a variable resistance layer with oxygen-deficient regions is used to enable resistance change, then the memory element can store information, but non-uniformity of resistance values and read currents occurs
Solution Approach 1:
The patent applies local quality by creating a multi-layer structure where different regions have different oxygen content. The variable resistance layer includes a first region with higher oxygen content and a second region with lower oxygen content, allowing each region to perform its specific function: the first region provides uniform electrical characteristics while the second region enables resistance change through oxygen ion migration.
Solution Approach 2:
The patent uses composite materials by combining multiple metal oxide layers with different compositions and oxygen contents. The variable resistance layer is composed of at least two different metal oxides with different standard electrode potentials, creating a composite structure that achieves both uniformity and variability in resistance characteristics.
2Power
If oxygen-deficient regions extend freely to enable resistance switching, then switching current is reduced, but non-uniformity of read currents increases causing read errors
Solution Approach 1:
The patent restricts oxygen-deficient regions to specific local areas within the variable resistance layer, particularly in the second region with lower oxygen content. This localized approach allows resistance switching to occur with lower current while preventing the uncontrolled extension of oxygen-deficient regions that would cause read current non-uniformity.
Solution Approach 2:
The patent segments the variable resistance layer into multiple regions with different oxygen content characteristics. By dividing the layer into a first region with higher oxygen content and a second region with lower oxygen content, the patent enables independent control of resistance switching behavior and read current uniformity in each segment.
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 non-uniformity of resistance values and read currents, enhancing the accuracy of determining the resistance state and minimizing read errors while decreasing switching current, thus improving the overall performance and reliability of the memory device.
Implementation Method 1
a variable resistance layer which is interposed between the first electrode and the second electrode and reversibly changes its resistance value in response to an electric signal applied between the first electrode and the second electrode
Data Source
AI summary
A non-volatile memory element including a first electrode; a second electrode; and a variable resistance layer. The variable resistance layer including, when a first metal is M and a second metal is N: a third metal oxide layer NOz; a second metal oxide layer NOy; and a first metal oxide layer MOx such that the third, second and first metal oxide layers are stacked in this order; wherein when an oxygen content atomic percentage of an oxide of the first metal M in a stoichiometric state is A, an oxygen content atomic percentage of an oxide of the second metal N in a stoichiometric state is B, an oxygen content atomic percentage of MOx is C, an oxygen content atomic percentage of NOy is D, and an oxygen content atomic percentage of NOz is E, (D/B)<(C/A), (E/B)<(C/A) and y<z are satisfied.