MRAM Memory Element Using CoFeB and Tunnel Barrier
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Magnetic random access memory (MRAM) devices face challenges in maintaining thermal stability and reducing write current while miniaturizing, as the coercive force and saturation magnetization of the memory layer affect the reliability of stored information.
Innovation Solution
A memory element configuration with a magnetization-fixed layer and a memory layer separated by an insulating layer, where spin-polarized electrons are injected to invert the magnetization direction, reducing the effective diamagnetic field and write current, and using Co—Fe—B materials to enhance thermal stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the coercive force and saturation magnetization of the memory layer are increased to maintain thermal stability, then the reliability of stored information is improved, but the write current increases
Solution Approach 1:
The patent divides the magnetic memory structure into distinct segments: a memory layer for storing information and a separate magnetization-fixed layer for providing stable magnetic reference. This segmentation allows the memory layer to have optimized magnetic properties for low write current while the fixed layer maintains thermal stability, resolving the contradiction between reliability and energy consumption.
Solution Approach 2:
The patent introduces a tunnel barrier layer as an intermediary between the memory layer and magnetization-fixed layer. This intermediary structure enables spin-polarized electron injection with high efficiency, allowing magnetization switching at lower current densities. The tunnel barrier facilitates the transfer of spin angular momentum while maintaining the magnetic stability needed for reliable information retention.
2Use of energy by moving object
If the memory layer thickness is reduced to minimize write current, then the write current is diminished, but the thermal stability deteriorates
Solution Approach 1:
The patent transitions from in-plane magnetization to perpendicular magnetization geometry. This dimensional change in magnetization orientation enables thinner memory layers to achieve sufficient thermal stability through perpendicular magnetic anisotropy, while simultaneously reducing the write current required for switching. The perpendicular configuration provides stronger magnetic anisotropy energy density in the thin film direction.
Solution Approach 2:
The patent employs composite material structures including CoFeB (cobalt-iron-boron) alloy in the memory layer combined with specific tunnel barrier materials. This composite structure provides both perpendicular magnetic anisotropy for thermal stability in thin layers and high spin polarization for efficient spin injection, resolving the trade-off between thickness and stability.
3Use of energy by moving object
If spin injection efficiency is increased to reduce write current, then the write current is reduced, but the device complexity increases
Solution Approach 1:
The patent optimizes key parameters including the thickness of the memory layer, tunnel barrier layer, and magnetization-fixed layer, as well as the composition ratios of CoFeB alloy. By carefully controlling these parameters, the patent achieves high spin injection efficiency with a relatively simple layered structure, minimizing write current without excessive complexity. The parameter optimization enables efficient spin-polarized electron transport through the tunnel barrier.
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 diminishes the write current while maintaining sufficient thermal stability, ensuring reliable information retention and reducing power consumption in MRAM devices.
Implementation Method 1
an electron that is spin-polarized is injected in a lamination direction of a layered structure having the memory layer, the insulating layer, and the magnetization-fixed layer, and thereby the magnetization direction of the memory layer varies
Implementation Method 2
a memory layer that stores the magnetization state of a ferromagnetic layer as information
Implementation Method 3
a magnetization-fixed layer in which a magnetization direction is fixed
Data Source
AI summary
There is disclosed a memory element including a memory layer that has a magnetization and a magnetization direction thereof varies corresponding to information; a magnetization-fixed layer that has a magnetization; and an insulating layer that is provided between the memory layer and the magnetization-fixed layer, wherein an electron that is spin-polarized is injected in a lamination direction of a layered structure, and thereby the magnetization direction of the memory layer varies and a recording of information is performed with respect to the memory layer, and a Ta film in contact with a face of the magnetization-fixed layer, the face of the magnetization-fixed layer is opposite to the insulating layer side.