Stacked Variable Resistive Memory With Multi-Level Filament Control
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Solution Overview
Problem
Current nonvolatile variable resistive devices face challenges in achieving multi-level storage and efficient resistance switching due to limitations in controlling conductive filament formation and dissolution, leading to issues with data retention and reading accuracy.
Innovation Solution
The device employs a configuration with two variable resistive layers and a semiconductor electrode, where the metal elements of the electrodes are selected to differ in diffusion rate, ionization energy, and cohesive energy, allowing for distinct drive voltages and polarities to control the formation and dissolution of conductive filaments, enabling multi-level resistance switching and improved controllability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single variable resistive layer is used, then the device structure is simple, but multi-level storage capability is limited
Solution Approach 1:
The patent divides the single variable resistive layer into multiple stacked variable resistive layers (first variable resistive layer and second variable resistive layer). Each layer can independently form or dissolve conductive filaments, enabling multi-level resistance states and从而实现 multi-level storage capability while maintaining a relatively compact structure.
Solution Approach 2:
The patent transitions from a single-layer two-terminal device to a multi-layer stacked structure with selective electrode connections. By stacking variable resistive layers and selectively connecting them to electrodes through insulating layers, the device achieves multi-level storage in the vertical dimension, effectively adding a new spatial dimension to the storage mechanism.
2Ease of manufacture
If metal elements with similar properties are used in electrodes, then the device is easy to manufacture, but controllability of conductive filament formation and dissolution is poor
Solution Approach 1:
The patent assigns different metal elements with distinct properties to different electrodes (first electrode and third electrode). The first electrode uses a metal element with higher diffusion rate, lower ionization energy, and lower cohesive energy, while the third electrode uses a metal element with lower diffusion rate, higher ionization energy, and higher cohesive energy. This local differentiation enables independent control of conductive filament formation and dissolution in each variable resistive layer through selective voltage application.
Solution Approach 2:
The patent exploits differences in key parameters (diffusion rate, ionization energy, cohesive energy) of metal elements to achieve controllable resistance switching. By selecting metal elements with significantly different values for these parameters, the device can selectively form or dissolve conductive filaments in specific variable resistive layers by applying appropriate voltages, thereby achieving precise controllability of resistance changes.
3Device complexity
If conventional single-layer devices are used, then the manufacturing process is simple, but data retention and reading accuracy are insufficient
Solution Approach 1:
The patent segments the storage function across multiple variable resistive layers, where each layer contributes to the overall resistance state. This segmentation allows for more robust data retention as the multi-layer structure provides additional states and redundancy, improving reading accuracy through the cumulative effect of multiple resistance switching events.
Solution Approach 2:
The patent employs a composite structure consisting of multiple variable resistive layers with different metal element compositions, insulating layers, and electrode materials. This composite architecture enhances device performance by combining the advantages of different materials and structures, leading to improved data retention and reading accuracy compared to conventional single-layer devices.
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 allows for the realization of multi-level nonvolatile memory with increased tolerance of resistance values, reducing erroneous data reading and enhancing the controllability of resistance changes, thereby improving the device's storage capabilities.
Implementation Method 1
the first variable resistive layer is arranged between the first electrode and the second electrode and is capable of reversibly changing a resistance by filament formation and dissolution of the metal element of the first electrode
Implementation Method 2
the second variable resistive layer is arranged between the second electrode and the third electrode and is capable of reversibly changing a resistance by filament formation and dissolution of the metal element of the third electrode
Implementation Method 3
the first variable resistive layer is arranged between the first electrode and the second electrode and is capable of reversibly changing a resistance by filament formation and dissolution of the metal element of the first electrode
Data Source
AI summary
According to one embodiment, a first electrode includes a metal element. A second electrode includes a semiconductor element. A third electrode includes a metal element. A first variable resistive layer is arranged between the first electrode and the second electrode and is capable of reversibly changing a resistance by filament formation and dissolution of the metal element of the first electrode. A second variable resistive layer is arranged between the second electrode and the third electrode and is capable of reversibly changing a resistance by filament formation and dissolution of the metal element of the third electrode.