ReRAM Core-Shell Oxide Interface Dipole Filament Control
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Solution Overview
Problem
Conventional resistive random-access memory (ReRAM) cells experience random filament placement, leading to higher forming voltage and variability as they are scaled, which complicates the process and increases costs due to non-planar designs intended to enhance electric field distribution.
Innovation Solution
The use of a core and shell oxide configuration with interface dipoles, where a high group electron negativity material forms the core and a low group electron negativity material forms the spacers, creating a controlled environment for filament formation by confining current flows to the center of the ReRAM cell.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of moving object
If conventional ReRAM cells are scaled down, then device density is improved, but forming voltage increases and variability worsens due to random filament placement
Solution Approach 1:
The patent applies local quality by creating a non-uniform oxide structure with different regions having different properties: a first oxide region with higher oxygen vacancy concentration and a second oxide region with lower oxygen vacancy concentration. This local differentiation enables controlled filament formation in specific regions, addressing the random placement issue while maintaining scalability.
Solution Approach 2:
The patent changes the oxygen vacancy concentration parameter within the oxide layer to control filament formation. By creating regions with different oxygen vacancy concentrations through selective processing, the invention enables deterministic filament placement rather than random formation, thereby controlling forming voltage while scaling down device dimensions.
2Manufacturing precision
If non-planar designs are used to enhance electric field distribution, then filament formation control is improved, but process complexity and costs increase
Solution Approach 1:
The patent segments the oxide layer into distinct regions with different oxygen vacancy concentrations. This segmentation is achieved through selective processing steps that create spatially differentiated oxide regions, enabling controlled electric field distribution and filament formation while maintaining a planar device structure that avoids the complexity of non-planar designs.
Solution Approach 2:
The patent replaces the mechanical/geometric approach of non-planar designs with a chemical/compositional approach using varying oxygen vacancy concentrations in planar oxide regions. This substitution achieves enhanced electric field control through material composition rather than structural geometry, thereby reducing process complexity.
3Reliability
If random filament placement occurs, then device variability increases, but forming voltage remains high
Solution Approach 1:
By creating local regions with different oxygen vacancy concentrations, the patent ensures that filaments form in predetermined locations rather than randomly. This local quality control reduces device-to-device variability and enables lower forming voltages by concentrating the electric field in specific high-oxygen-vacancy regions.
Solution Approach 2:
The oxide structure with varying oxygen vacancy concentrations essentially guides the filament formation process itself. The high oxygen vacancy regions naturally attract and confine the forming process, making the system self-organizing and eliminating the need for external control mechanisms, thereby reducing variability and forming voltage simultaneously.
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 facilitates controlled filament formation in the center of ReRAM cells, reducing forming voltage variability and enhancing scalability while maintaining a planar design simplicity, thus improving the reliability and efficiency of ReRAM devices.
Implementation Method 1
a combination of the low group electron negativity material for the spacers and the high group electron negativity material for the core generates an interface dipole pointing toward the core
Data Source
AI summary
Resistive memory with core and shell oxides and interface dipoles for controlled filament formation is provided. In one aspect, a ReRAM device includes at least one ReRAM cell having a substrate; a bottom electrode disposed on the substrate; spacers formed from a low group electron negativity material disposed on the bottom electrode; a core formed from a high group electron negativity material present between the spacers; and a top electrode over and in contact with the spacers and the core, wherein a combination of the low group electron negativity material for the spacers and the high group electron negativity material for the core generates an interface dipole pointing toward the core. Methods of forming and operating a ReRAM device are also provided.