Nonvolatile Memory Device Intermediate Layer Stress Management
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Solution Overview
Problem
Current nonvolatile memory devices face challenges in increasing bit density while maintaining stable retention characteristics and suppressing operating voltage, particularly in resistive random access memory (ReRAM) where the stress on conducting filaments affects retention and bit density.
Innovation Solution
A nonvolatile memory device structure is implemented with a first conductive layer, a second conductive layer, and an intermediate layer, where the intermediate layer includes specific oxide compositions and oxygen concentration gradients to reduce stress on conducting filaments, improving retention characteristics and allowing for higher bit density without increasing operating voltage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If bit density is increased by reducing cell size, then storage capacity improves, but stress on conducting filaments increases causing degradation of retention characteristics
Solution Approach 1:
A first intermediate layer is introduced between the conducting filament and the electrode to act as a mediator. This intermediate layer includes a first oxide with a first band gap that is smaller than the second oxide's band gap, allowing it to selectively passivate stress while maintaining electrical functionality. The intermediate layer absorbs and dissipates stress before it reaches the conducting filament, thereby preserving retention characteristics even at high bit densities.
2Quantity of substance
If cell size is reduced to increase bit density, then storage capacity improves, but operating voltage increases
Solution Approach 1:
The patent modifies the band gap parameter of the oxide materials in the intermediate layer. By selecting a first oxide with a smaller band gap than the second oxide, the electrical characteristics are optimized to maintain lower operating voltages. This parameter change in material selection allows the device to sustain reduced voltage operation even as cell dimensions are scaled down for higher bit density.
3Power
If conducting filament stress is increased to improve switching performance, then resistance change improves, but retention characteristics deteriorate
Solution Approach 1:
The first intermediate layer serves as a protective intermediary between the conducting filament and the electrode. It allows sufficient stress transmission for effective switching while simultaneously providing stress passivation to prevent excessive stress accumulation. This dual function enables good switching performance while maintaining reliable retention characteristics over time.
Solution Approach 2:
The intermediate layer is positioned specifically at the interface where stress concentration occurs between the conducting filament and electrode. By applying this protective layer locally at the critical stress interface rather than throughout the entire device, the patent achieves effective stress management while maintaining overall device performance.
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 enhances the retention characteristics of conducting filaments and allows for increased bit density in nonvolatile memory devices by reducing stress and maintaining stable operations, even at small cell sizes.
Implementation Method 1
the stress on conducting filaments affects retention and bit density
Data Source
AI summary
According to one embodiment, a nonvolatile memory device includes a first conductive layer, a second conductive layer, and an intermediate layer. The first conductive layer includes a first element. The first element includes a at least one selected from the group consisting of Ag, Cu, Ni, Co, Ti, Al, and Au. The intermediate layer is provided between the first conductive layer and the second conductive layer. The intermediate layer includes an oxide. The oxide includes a second element and a third element. The second element includes at least one second element being selected from the group consisting of Ti, Ta, Hf, W, Mg, Al, and Zr. The third element is different from the second element and includes at least one selected from the group consisting of Si, Ge, Hf, Al, Ta, W, Zr, Ti, and Mg.