Variable Resistance Memory Device Asymmetry Leakage Current
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Solution Overview
Problem
Variable resistance memory devices with a cross-point structure face issues of leakage current and power consumption due to unselected cells being affected during read operations, as the write voltage applied to a selected cell changes the state of unselected cells in the CRS structure.
Innovation Solution
A variable resistance memory device with symmetrical first and second structures, each comprising a first electrode, a second electrode, and a variable resistance material layer, and a material layer that passes bidirectional current, allowing for distinct set and reset voltages to prevent data alteration during read operations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If a cross-point structure with CRS is used to increase integration degree, then leakage current is reduced and power consumption is reduced, but data in unselected cells is altered during write operations
Solution Approach 1:
The patent introduces an asymmetric material layer with different resistance states (first resistance state and second resistance state) to break the symmetry of the CRS structure. This asymmetry allows selective modification: the material layer's resistance changes in response to write voltages, while the variable resistance material layers in unselected cells remain unaffected, preventing data alteration while maintaining low power consumption benefits
Solution Approach 2:
The material layer acts as an intermediary element between the CRS structures and the variable resistance material layers. It mediates the write operation by being the primary component that undergoes resistance state changes, thereby protecting the data stored in variable resistance material layers of unselected cells from being altered during write operations
2Productivity
If write voltage is applied to selected cell in cross-point structure, then data is written to selected cell, but read operation is performed on unselected cells causing data alteration
Solution Approach 1:
The patent applies local quality by making the material layer have distinct resistance states that are locally affected by write voltages. The material layer's resistance changes are localized to the selected cell's write operation, while unselected cells experience different voltage conditions that do not trigger resistance changes in their variable resistance material layers, thus preventing unintended data alteration
Solution Approach 2:
The patent utilizes parameter changes by introducing a material layer with switchable resistance states (first resistance state and second resistance state). During write operations, the resistance state of the material layer changes in response to applied voltages, creating a differential effect that enables writing to selected cells while preserving data in unselected cells through different resistance response characteristics
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 solution reduces leakage current and power consumption by maintaining the resistance state of unselected cells during write operations, ensuring accurate data storage and retrieval without altering the data in unselected cells.
Implementation Method 1
a variable resistance material layer interposed between two electrodes for voltage application... a variable resistance material layer interposed between the first and second electrodes and configured to switch between different resistance states depending on a voltage applied across the variable resistance material layer
Implementation Method 2
a material layer interposed between the first and second structures and configured to pass a bidirectional current according to a voltage applied across the material layer
Data Source
AI summary
A variable resistance memory device includes: first and second structures that each include a first electrode, a second electrode, and a variable resistance material layer interposed between the first and second electrodes and configured to switch between different resistance states depending on a voltage applied across the variable resistance material layer; and a material layer interposed between the first and second structures and configured to pass a bidirectional current according to a voltage applied across the material layer. The first and second structures are symmetrical with respect to the material layer.