Perpendicular Magnetic Memory Reducing Switching Current
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Solution Overview
Problem
Current non-volatile magnetic memory technologies face challenges with high switching current and low thermal stability, making them unsuitable for scalable and reliable data storage solutions.
Innovation Solution
A magnetic storage memory device is designed with a specific layered structure, including a bottom electrode, pinning layer, fixed layer, tunnel layer, free layers, and a cap layer, which reduces switching current while maintaining high thermal stability through current-induced magnetization switching and exchange coupling between grains.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If conventional magnetic memory structures are used, then thermal stability is improved, but switching current becomes excessively high
Solution Approach 1:
The magnetic memory structure is segmented into distinct functional layers: a pinned layer with fixed magnetization, a tunnel barrier layer, and a free layer with switchable magnetization. This segmentation allows the pinned layer to provide thermal stability while the free layer undergoes magnetization switching, thereby reducing the switching current requirement compared to conventional uniform magnetic structures.
Solution Approach 2:
Different regions of the magnetic memory structure are assigned different magnetic properties: the pinned layer has strong magnetic anisotropy and fixed magnetization for stability, while the free layer has weaker anisotropy and switchable magnetization for low-current switching. The tunnel barrier layer provides localized spin polarization that enhances the switching efficiency. This local differentiation of magnetic qualities enables simultaneous achievement of thermal stability and low switching current.
2Volume of moving object
If memory dimension is decreased for scalability, then device size is reduced, but reliability and thermal stability deteriorate
Solution Approach 1:
The patent transitions from in-plane magnetization switching to perpendicular magnetization switching by orienting the magnetic moments perpendicular to the film plane. This dimensional change in magnetization orientation enables better thermal stability and reliability at reduced dimensions because perpendicular anisotropy provides stronger stabilization against thermal fluctuations at smaller volumes, thereby improving read-write endurance in scaled devices.
Solution Approach 2:
The magnetic memory structure employs composite material stacks including CoFeB (cobalt-iron-boron) for the free layer, CoFe (cobalt-iron) for the pinned layer, and MgO (magnesium oxide) for the tunnel barrier. These composite materials provide optimized magnetic properties, high spin polarization, and strong perpendicular anisotropy that maintain reliability and thermal stability even as device dimensions are reduced for scalability.
3Loss of energy
If switching current is reduced for lower power consumption, then power dissipation is improved, but thermal stability decreases
Solution Approach 1:
The tunnel barrier layer acts as an intermediary between the pinned layer and the free layer. It provides spin polarization to the free layer during current-induced switching while allowing the pinned layer to maintain its fixed magnetization and provide thermal stability. This intermediary role of the tunnel barrier enables low-power switching without compromising the thermal stability provided by the pinned layer structure.
Solution Approach 2:
The patent utilizes changes in magnetic anisotropy parameters and layer thicknesses to optimize the balance between switching current and thermal stability. By adjusting the thickness and composition of the free layer and pinned layer, and by engineering the perpendicular magnetic anisotropy strength, the structure achieves low switching current through spin-transfer torque while maintaining sufficient thermal stability for reliable data retention.
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 achieves lower switching current and higher thermal stability, enabling more reliable and efficient data storage with improved scalability and reduced power consumption.
Implementation Method 1
current-induced magnetization switching
Implementation Method 2
exchange coupling between grains
Implementation Method 3
Non-volatile perpendicular magnetic memory
Data Source
AI summary
A non-volatile current-switching magnetic memory element includes a bottom electrode, a pinning layer formed on top of the bottom electrode, and a fixed layer formed on top of the pinning layer. The non-volatile current-switching magnetic memory element further includes a tunnel layer formed on top of the pinning layer, a first free layer with a perpendicular anisotropy that is formed on top of the tunnel layer, a granular film layer formed on top of the free layer, a second free layer formed on top of the granular film layer, a cap layer formed on top of the second layer, and a top electrode formed on top of the cap layer.