Resistance-Change Memory Cell Array With Rectifying Insulating Film
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Solution Overview
Problem
Resistance-change memory cell arrays face challenges in optimizing leakage current in unselected cells and ensuring sufficient current supply to selected cells, particularly in large-scale arrays with high integration density and high-speed response requirements, leading to increased power consumption and reduced switching yield.
Innovation Solution
The implementation of a cross-point structure with rectifying insulating films, variable resistance films, and conductive layers, where the area of the rectifying insulating film is smaller than the variable resistance film, enhancing the electric field applied to the rectifying insulating film to supply a large current to selected cells and reduce leakage currents, while minimizing electrode resistance and preventing shorting failures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the array scale is increased to enhance integration density, then the storage capacity is improved, but the leakage current in unselected cells increases leading to higher power consumption
Solution Approach 1:
The patent introduces a conductive layer with non-uniform conductivity distribution, creating regions of high conductivity near the variable resistance film and low conductivity in other areas. This local quality differentiation allows the cell to maintain low resistance when selected while preventing leakage current when unselected, thus resolving the contradiction between integration density and power consumption.
Solution Approach 2:
The patent changes the conductivity parameter of the conductive layer by creating a non-uniform distribution pattern. The conductivity varies spatially within the same layer, with higher values near the variable resistance film interface and lower values elsewhere. This parameter change enables the structure to achieve both low on-resistance and low off-leakage current, addressing the power consumption issue in large-scale arrays.
2Reliability
If the current supplied to selected cells is increased to improve switching yield, then the switching reliability is improved, but the power consumption increases
Solution Approach 1:
The conductive layer is designed with localized high-conductivity regions positioned precisely where needed for current flow to the variable resistance film. This ensures that sufficient current is delivered to selected cells for reliable switching while minimizing current leakage in other regions, thus achieving high switching yield without excessive power consumption.
3Power
If the area of the rectifying insulating film is reduced to increase the electric field strength, then the current supply to selected cells is improved, but the leakage current control may be compromised
Solution Approach 1:
The patent compensates for the reduced rectifying insulating film area by introducing a conductive layer with spatially varying conductivity. The high-conductivity regions are positioned to concentrate current flow through the smaller insulating film area, maintaining sufficient current supply capability while the low-conductivity regions provide leakage current suppression, thus balancing both requirements.
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 effectively reduces power consumption, enhances switching yield, and prevents 'read disturb failure' by optimizing the electric field distribution, particularly suitable for phase-change switching materials, while maintaining low switching voltages and avoiding erroneous operations.
Implementation Method 1
rectifying insulating films formed in contact with side surfaces of the vertical electrodes in facing regions between the horizontal electrodes and the vertical electrodes
Implementation Method 2
variable resistance films formed in contact with side surfaces of the horizontal electrodes in the facing regions between the horizontal electrodes and the vertical electrodes
Implementation Method 3
conductive layers formed between the rectifying insulating films and the variable resistance films
Data Source
AI summary
According to one embodiment, a resistance-change memory cell array in which a plurality of horizontal electrodes extending horizontally and a plurality of vertical electrodes extending vertically are arranged to configure a cross-point structure includes rectifying insulating films formed in contact with side surfaces of the vertical electrodes in facing regions between the horizontal electrodes and the vertical electrodes, variable resistance films formed in contact with side surfaces of the horizontal electrodes in the facing regions between the horizontal electrodes and the vertical electrodes, and conductive layers formed between the rectifying insulating films and the variable resistance films.