Nonvolatile Memory Device with Concentration-Graded Electrode
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Solution Overview
Problem
Existing nonvolatile memory devices face challenges in achieving high repeated-operational stability due to fluctuations in the resistance states of resistance change materials, which affect their recording density and reliability.
Innovation Solution
A nonvolatile memory device configuration featuring a recording layer made of a main group element, a transition element, and oxygen, with a conductive upper electrode having a lower concentration of the main group element than the recording layer, allowing for reversible resistance state changes and improved operational stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If a resistance change material is used to achieve high recording density, then the recording density is improved, but the repeated-operational stability deteriorates due to fluctuations in resistance states
Solution Approach 1:
The patent applies parameter changes by precisely controlling the concentration of main group elements in the recording layer and the composition of the upper electrode. By adjusting these compositional parameters, the device achieves both high recording density and stable resistance state transitions during repeated operations.
Solution Approach 2:
The patent uses composite materials by combining a main group element (In, Ga, or Al), a transition element (Fe, Co, or Ni), and oxygen to form the recording layer. This composite structure enables reversible resistance changes while maintaining operational stability, resolving the contradiction between recording density and reliability.
2Ease of manufacture
If the upper electrode has the same composition as the recording layer, then the manufacturing process is simplified, but the operational stability deteriorates
Solution Approach 1:
The patent applies local quality by making the upper electrode's composition different from the recording layer's composition. Specifically, the upper electrode has a lower concentration of main group elements, which creates optimal local conditions for stable resistance state transitions while the recording layer maintains high recording density.
3Ease of manufacture
If the concentration of main group element in the upper electrode is high, then the formation process is easier, but the repeated-operational stability deteriorates
Solution Approach 1:
The patent applies parameter changes by optimizing the concentration of main group elements in the upper electrode to be lower than in the recording layer. This parameter adjustment ensures stable resistance state transitions during repeated operations while still allowing for feasible formation processes.
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 configuration enables stable and repeatable transitions between high and low resistance states, enhancing the operational stability and reliability of the nonvolatile memory device.
Implementation Method 1
The recording layer is capable of recording information by changing reversibly between a high resistance state and a low resistance state
Data Source
AI summary
According to one embodiment, a nonvolatile memory device includes a recording layer and a conductive first layer. The recording layer includes a main group element, a transition element, and oxygen. The recording layer is capable of recording information by changing reversibly between a high resistance state and a low resistance state. The first layer is made of at least one selected from a metal, a metal oxide, a metal nitride, and a metal carbide. The first layer is provided adjacent to the recording layer. The first layer includes the main group element with a concentration lower than a concentration of the main group element of the recording layer.