Magnetic Tunnel Junctions With Iridium Region For Stable Coupling
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Solution Overview
Problem
Magnetic tunnel junctions require strong magnetic coupling to maintain stable magnetic orientation for spin-torque-transfer magnetic random access memory applications, but existing technologies face challenges in achieving consistent and stable magnetic coupling across regions.
Innovation Solution
Incorporating an iridium-containing region between the polarizer and other magnetic regions of the reference material to enhance magnetic coupling, which can be either antiferromagnetic or ferromagnetic depending on thickness, and using a multi-layer stack with cobalt, platinum, palladium, and nickel layers to achieve perpendicular magnetic anisotropy and pinning stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional magnetic coupling structures are used in magnetic tunnel junctions, then device complexity is reduced, but magnetic coupling stability and spin-orientation consistency deteriorate
Solution Approach 1:
The reference material is divided into distinct functional regions: a polarizer region containing CoFeB material and an iridium-containing region with specific thickness (2-20 nm). This segmentation allows each region to perform its specialized function - the polarizer region generates spin-polarized current while the iridium region provides stable magnetic coupling and perpendicular magnetic anisotropy, thereby resolving the contradiction between reliability and complexity.
Solution Approach 2:
The iridium-containing region acts as an intermediary layer between the polarizer region and other magnetic regions. It mediates the magnetic coupling interaction, providing both antiferromagnetic and ferromagnetic coupling mechanisms depending on its thickness, which ensures consistent spin-orientation stability while maintaining manageable device complexity through a well-defined intermediate structure.
2Use of energy by moving object
If CoFeB material is used in the polarizer region, then spin-polarized current generation is improved, but manufacturing precision requirements increase due to amorphous-to-crystalline transformation
Solution Approach 1:
The CoFeB material is initially deposited in an amorphous state during the deposition process, which simplifies manufacturing. The perpendicular magnetic anisotropy and bcc 001 lattice structure are then induced through subsequent annealing treatment. This preliminary action approach allows the material to be easily deposited first, then precisely controlled later, resolving the contradiction between spin-polarized current efficiency and manufacturing precision.
Solution Approach 2:
The material undergoes parameter changes from amorphous to crystalline state with specific bcc 001 lattice orientation through controlled annealing. This parameter transformation enables the CoFeB material to achieve the desired spin-polarized current efficiency while the annealing process provides precise control over the lattice structure, thereby resolving the manufacturing precision challenge.
3Productivity
If tunnel insulator material is made sufficiently thin to enable electron tunneling, then memory writing capability is improved, but tunnel insulator integrity and leakage control become more difficult
Solution Approach 1:
The tunnel insulator material (MgO) is processed to achieve a specific thickness range (1-3 nm) that balances electron tunneling efficiency with structural integrity. The crystalline structure with bcc 001 lattice is maintained through controlled deposition and annealing processes, ensuring that the insulator remains stable and leak-free even at these reduced thicknesses, thus resolving the contradiction between writing speed and reliability.
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 iridium-containing region provides stable magnetic coupling up to 7 kilo-Oersteds, ensuring consistent spin-orientation stability and improved magnetic properties, enhancing the performance of magnetic tunnel junctions in memory applications.
Implementation Method 1
A spin-polarized current is one with significantly more electrons of either spin. By passing a current through certain magnetic material (sometimes also referred to as polarizer material), one can produce a spin-polarized current. If a spin-polarized current is directed into a magnetic material, spin angular momentum can be transferred to that material, thereby affecting its magnetization orientation.
Implementation Method 2
Electrical resistance between those two nodes through the reference electrode, insulator material, and the recording electrode is dependent upon the magnetization direction of the recording electrode relative to that of the reference electrode.
Data Source
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AI summary
Some embodiments include a magnetic tunnel junction comprising magnetic reference material having an iridium-containing region between a multi-layer stack and a polarizer region. Some embodiments include a magnetic tunnel junction having a conductive first magnetic electrode which contains magnetic recording material, a conductive second magnetic electrode spaced from the first electrode and which contains magnetic reference material, and a non-magnetic insulator material between the first and second electrodes. The magnetic reference material of the second electrode includes a first region containing a stack of cobalt alternating with one or more of platinum, palladium and nickel; includes an iridium-containing second region over the first region; and includes a cobalt-containing third region over the second region. The third region is directly against the non-magnetic insulator material.