Phase Change Memory Current Density Control via Insulated Conductor
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Solution Overview
Problem
Phase change memory cells require high operating currents, which is undesirable for low power consumption, and current density is typically maximized at the bottom electrode interface, limiting applications where increased current density above the bottom electrode is needed.
Innovation Solution
A phase change memory element is constructed with a first and second electrode, a phase change material layer, a metal chalcogenide layer, and an insulating layer with openings to increase current density at a desired height above the bottom electrode by channeling current through these openings.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the size of the bottom electrode is decreased to increase current density, then current density at the bottom electrode interface is maximized, but the overall current requirements for the memory cell are not sufficiently reduced and applications requiring current density above the bottom electrode are limited
Solution Approach 1:
The patent introduces a vertical dimension to current density control by positioning a conductive layer above the bottom electrode at a specific height, rather than only modifying the bottom electrode interface. This allows current density to be maximized at multiple locations along the vertical axis, enabling both bottom electrode interface optimization and upper region current concentration for different application needs.
Solution Approach 2:
The patent segments the current path into multiple zones by introducing a conductive layer with openings at a specific height above the bottom electrode. This creates distinct current concentration regions: one at the bottom electrode interface and another above the phase change material, allowing independent optimization for different operational requirements.
2Reliability
If large write current pulses are applied to achieve amorphous state, then phase change material transitions to amorphous phase, but power consumption increases
Solution Approach 1:
The patent applies local quality by creating concentrated current paths through openings in the conductive layer, which locally maximizes current density at specific positions above the bottom electrode. This localized current concentration enables more efficient heating of the phase change material, reducing the overall current required to achieve the necessary temperature for phase transition and thereby lowering power consumption.
Solution Approach 2:
The patent utilizes phase transitions of the phase change material (amorphous to crystalline and vice versa) by controlling current density distribution. The conductive layer with openings enables precise thermal control during phase transitions, allowing efficient switching between states with reduced energy input compared to conventional uniform current distribution methods.
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 increased current density at a location above the bottom electrode, reducing the overall current requirements for phase change memory cells and enhancing their operational efficiency.
Implementation Method 1
A portion of the phase change material is set to a particular resistance state according to the amount of current applied via the electrodes. To obtain an amorphous state, a relatively high write current pulse (a reset pulse) is applied through the phase change cell to melt a portion of the material
Implementation Method 2
Phase change materials have been investigated for use in non-volatile memory cells. Phase change memory cells include phase change materials, such as chalcogenide alloys, which are capable of stably transitioning between amorphous and crystalline phases.
Implementation Method 3
The current is removed and the cell cools rapidly to a temperature below the glass transition temperature, which results in the portion of the material having an amorphous phase.
Data Source
AI summary
A phase change memory element and method of forming the same. The memory element includes first and second electrodes. A first layer of phase change material is between the first and second electrodes. A second layer including a metal-chalcogenide material is also between the first and second electrodes and is one of a phase change material and a conductive material. An insulating layer is between the first and second layers. There is at least one opening in the insulating layer providing contact between the first and second layers.