Variable Resistance Layer Segmentation for Low Voltage Breakdown
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Solution Overview
Problem
Conventional nonvolatile memory elements require high initial breakdown voltage for normal resistance change, leading to potential electric damage and inefficiency, and necessitate a dedicated high voltage generation circuit.
Innovation Solution
A nonvolatile memory element with a variable resistance layer comprising a first metal oxide and a second metal oxide with a lower oxygen deficient degree, where the second variable resistance layer includes an insulating part, reducing the cross-sectional area for operation current and allowing initial breakdown at a lower voltage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional variable resistance layer structure is used, then the memory element can achieve normal resistance change, but it requires very high initial breakdown voltage which causes electric damage and inefficiency
Solution Approach 1:
The variable resistance layer is segmented into multiple sub-layers with different oxygen content. The first sub-layer has higher oxygen content (lower oxygen deficient degree) while the second sub-layer has lower oxygen content (higher oxygen deficient degree). This segmentation allows the structure to achieve both low initial breakdown voltage and stable resistance change, as each sub-layer contributes differently to the overall electrical characteristics.
Solution Approach 2:
Different regions of the variable resistance layer are given different local properties through varying oxygen content. The first sub-layer with higher oxygen content provides stability and controls the initial breakdown voltage, while the second sub-layer with lower oxygen content enables the resistance change mechanism. This local quality differentiation resolves the contradiction between reliability and harmful electric effects.
2Reliability
If high initial breakdown voltage is applied to form conductive path, then the memory element becomes operable, but it requires dedicated high voltage generation circuit increasing device complexity
Solution Approach 1:
The invention changes the physical parameters of the variable resistance layer by controlling the oxygen content in different sub-layers. By adjusting the oxygen content atomic percentage in each sub-layer, the initial breakdown voltage is reduced to a level that can be achieved without dedicated high voltage generation circuits, thereby reducing device complexity while maintaining operability.
3Reliability
If higher oxygen content atomic percentage is used in variable resistance layer, then oxidation-reduction reaction is stabilized, but the initial breakdown voltage becomes very high
Solution Approach 1:
The variable resistance layer is divided into sub-layers with different oxygen content atomic percentages. The first sub-layer has higher oxygen content (60-80 at%) providing stable oxidation-reduction reaction, while the second sub-layer has lower oxygen content (40-60 at%) reducing the initial breakdown voltage. This segmentation allows both requirements to be satisfied simultaneously.
Solution Approach 2:
The variable resistance layer uses a composite structure of multiple sub-layers with different oxygen content. This composite material approach combines the benefits of high oxygen content (reaction stability) and low oxygen content (low breakdown voltage) in a single integrated structure, resolving the technical contradiction.
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 reduces leak current and increases operation current concentration, enabling initial breakdown at a lower voltage without the need for a high voltage generation circuit, improving efficiency and stability.
Implementation Method 1
application of an electric pulse or the like changes a resistance value of the variable resistance layer from high to low or from low to high... selectively cause oxidation-reduction reaction near an interface between an electrode and a variable resistance layer
Data Source
AI summary
A nonvolatile memory element includes: a first electrode; a second electrode; and a variable resistance layer between the first and second electrodes. The variable resistance layer having a resistance value that reversibly changes according to an electrical signal provided between the electrodes. The variable resistance layer includes a first variable resistance layer and a second variable resistance layer. The first variable resistance layer comprises a first metal oxide. The second variable resistance layer is planar and includes a first part and a second part. The first part comprises a second metal oxide and is planar. The second part comprises an insulator and is planar. The second metal oxide has a lower oxygen deficient degree than that of the first metal oxide. The first and second parts are in contact with different parts of a main surface of the first variable resistance layer which faces the second variable resistance layer.