Nonvolatile Memory Electrode Curvature for Field Control
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Solution Overview
Problem
Resistance change type nonvolatile memory devices face challenges in stabilizing operation and maintaining uniform characteristics, particularly in the formation of electric field concentration points which can lead to unreliable performance and reduced reliability.
Innovation Solution
A nonvolatile memory device configuration with a first conductive layer, a second conductive layer, and a resistance change layer, where the second conductive layer has a corner part with higher curvature than its surface, allowing for controlled electric field concentration and filament formation, enhancing operational stability and uniformity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the thickness of the upper electrode is increased continuously from the periphery to the center to form a convex contact surface, then the operation failure is recovered, but the operation stability is insufficient
Solution Approach 1:
The upper electrode is designed with different thicknesses in different regions: a first thickness in the peripheral region and a greater second thickness in the central region. This local variation in thickness creates specific electric field concentration characteristics that improve operation stability while maintaining manufacturing feasibility.
Solution Approach 2:
The upper electrode forms a convex contact surface with the resistance change layer, creating a curved interface that concentrates the electric field at the contact point. This curvature effect enhances the reliability of operation by ensuring consistent filament formation while the controlled thickness variation maintains characteristic uniformity.
2Reliability
If a convex contact surface is formed to concentrate electric field, then operation failure is recovered, but excessive field concentration occurs leading to reduced reliability
Solution Approach 1:
The upper electrode implements localized thickness control where the peripheral region has a first thickness and the central region has a greater second thickness. This creates a controlled electric field distribution that concentrates the field at the convex contact surface for reliable operation while the peripheral thickness prevents excessive field concentration that would harm reliability.
Solution Approach 2:
The electrode thickness is increased in the central region relative to the periphery, creating partial excess thickness that forms the convex contact surface. This partial excess action is sufficient to achieve the desired electric field concentration for operation reliability without creating harmful excessive field concentration throughout the entire structure.
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 configuration ensures stable and uniform operation by controlling the position of electric field concentration, reducing excessive field concentration, and enabling efficient current passage, thereby improving the reliability and consistency of memory cell characteristics.
Implementation Method 1
the corner part has a curvature higher than a curvature of the third major surface... controlling the position of electric field concentration
Data Source
AI summary
A nonvolatile memory device includes first and second conductive layers, a resistance change layer, and a rectifying element. The first conductive layer has first and second major surfaces. The second conductive layer has third and fourth major surfaces, a side face, and a corner part. The third major surface faces the first major surface and includes a plane parallel to the first major surface and is provided between the fourth and first major surfaces. The corner part is provided between the third major surface and the side face and has a curvature higher than that of the third major surface. The resistance change layer is provided between the first and second conductive layers. The rectifying element faces the second major surface of the first conductive layer. An area of the third major surface is smaller than that of the second major surface.