Projected Memory Device Reducing Minimal Conductance
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Solution Overview
Problem
Phase-change memory devices face challenges in achieving low minimal conductance states, leading to increased power consumption and impaired network functionality due to high minimal conductance, which affects the efficiency of readout and programming.
Innovation Solution
A memory device design with a projection layer portion covering a smaller area than the phase-change material in the reset state, creating a discontinuity in conductance states, allowing the majority of the read current to bypass the amorphous phase-change material, thereby reducing minimal conductance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the projection layer covers the entire phase-change material area in reset state, then the read current can bypass the amorphous phase-change material effectively, but the minimal conductance increases substantially
Solution Approach 1:
The projection layer is segmented into a projection layer portion and non-projection layer portions, where only the projection layer portion directly covers the phase-change material. This segmentation allows the read current to bypass the amorphous phase-change material through the projection layer portion while preventing excessive current flow, thereby reducing minimal conductance and power consumption while maintaining low read noise through the projection structure.
2Reliability
If the projection layer covers the entire phase-change material area in reset state, then drift and noise are reduced, but the device dynamic range decreases
Solution Approach 1:
The projection layer is divided into a projection layer portion covering the phase-change material and non-projection layer portions at the edges. This segmentation creates a discontinuity in conductance states by allowing current to flow through the projection layer portion while blocking excessive flow at the edges, thereby maintaining low drift through the projection structure while preserving a wide dynamic range through the conductance discontinuity.
3Reliability
If the projection layer covers the entire phase-change material area, then the read current can flow through the projection material, but idle devices pass more current during readout
Solution Approach 1:
The projection layer is segmented such that only the projection layer portion directly covers the phase-change material while non-projection layer portions are positioned at the edges. This segmentation allows read current to flow through the projection layer portion with low noise, while the non-projection layer portions prevent idle devices from passing excessive current during readout, thereby improving both readout efficiency and maintaining low read noise.
4Adaptability or versatility
If the projection layer covers the entire phase-change material area, then the phase-change material can be fully utilized, but the minimal conductance state cannot be properly achieved
Solution Approach 1:
The projection layer is segmented into a projection layer portion and non-projection layer portions, creating a discontinuity that enables proper OFF state programming (G=0). The projection layer portion allows the phase-change material to be fully utilized for programming flexibility, while the non-projection layer portions prevent excessive current flow, thereby achieving both programming versatility and low power consumption in the minimal conductance state.
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 design significantly reduces drift and noise, enabling a higher dynamic range and lower power consumption, particularly beneficial for neuromorphic computing and deep neural networks by allowing precise encoding of zero weights and reducing overall network power consumption.
Implementation Method 1
phase-change material which can be switched reversely between a multitude of conductance states
Implementation Method 2
the phase-change material may enable a plurality of conductivity states depending on the ratio between a crystalline and an amorphous phase of the phase-change material
Implementation Method 3
The read current can bypass the amorphized phase-change material, whereby it flows through the not drifting, less noisy and higher conductive projection material
Data Source
AI summary
A memory device enabling a reduced minimal conductance state may be provided. The device comprises a first electrode, a second electrode and phase-change material between the first electrode and the second electrode, wherein the phase-change material enables a plurality of conductivity states depending on the ratio between a crystalline and an amorphous phase of the phase-change material. The memory device comprises additionally a projection layer portion in a region between the first electrode and the second electrode. Thereby, an area directly covered by the phase-change material in the amorphous phase in a reset state of the memory device is larger than an area of the projection layer portion oriented to the phase-change material, such that a discontinuity in the conductance states of the memory device is created and a reduced minimal conductance state of the memory device in a reset state is enabled.