Tunnel Magnetoresistive Device Using CoFeB-MgO Stack
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Solution Overview
Problem
Conventional tunnel magnetoresistive devices using Al oxides fail to provide sufficient electric output signals for industrial applications, and existing nonvolatile magnetic memories require higher output and lower power consumption, particularly in spin-transfer torque magnetization switching.
Innovation Solution
A tunnel magnetoresistive device is developed using a compound ferromagnetic film with a body-centered cubic structure of Co or Fe including B, combined with a magnesium oxide insulator film of a rock-salt structure, to enhance spin polarization and achieve higher tunnel magnetoresistance ratios.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If Al oxide is used in the insulator film of a tunnel magnetoresistive device, then the device structure is simple and easy to manufacture, but the electric output signal is insufficient for industrial applications
Solution Approach 1:
The patent changes the material parameter from Al oxide to MgO (magnesium oxide) in the insulator film, which fundamentally alters the electrical properties and enables sufficient electric output signals for industrial applications while maintaining the tunnel magnetoresistive device structure
Solution Approach 2:
The patent employs a composite structure combining MgO insulator film with specific ferromagnetic film compositions (CoFeB, CoFe) to achieve both high electric output signals and manageable manufacturing complexity through material composition optimization
2Reliability
If conventional tunnel magnetoresistive devices are used in nonvolatile magnetic memory, then the device structure is established, but the power consumption is high and output is insufficient
Solution Approach 1:
The patent optimizes the ferromagnetic film composition parameters (using CoFeB or CoFe with specific thickness ratios) and insulator film material (MgO) to enhance spin polarization, which increases the tunnel magnetoresistance ratio and reduces the current required for magnetization switching, thereby lowering power consumption
Solution Approach 2:
The patent applies different material compositions to different layers (CoFeB or CoFe in the ferromagnetic films, MgO in the insulator film) to optimize local spin polarization properties, enabling efficient spin-transfer torque switching with reduced power consumption
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 results in a high-output tunnel magnetoresistive device that enables fast and low-power-consuming nonvolatile magnetic memory, with improved magnetoresistance ratios and reduced power consumption during spin-transfer torque switching.
Implementation Method 1
tunnel magnetoresistive device comprising an insulator film, and first and second ferromagnetic films between which the insulator film is disposed
Implementation Method 2
there is also a so-called spin-transfer torque magnetization switching, which is also known as current induced magnetization switching
Data Source
AI summary
A fast and very low-power-consuming nonvolatile memory. A nonvolatile magnetic memory includes a high-output tunnel magnetoresistive device, in which spin-transfer torque is used for writing. A tunnel magnetoresistive device has a structure such that a ferromagnetic film of a body-centered cubic structure containing Co, Fe, and B, a MgO insulator film of a rock-salt structure oriented in (100), and a ferromagnetic film are stacked.