MRAM Storage Element with Spin Barrier and Absorption Layers

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Solution Overview

Problem

In magnetic random access memory (MRAM) devices, the challenge lies in maintaining stable thermal storage while reducing the current required for magnetization inversion, as finer elements lead to narrower address lines, making it difficult to pass sufficient current for magnetization inversion, and the Gilbert damping constant increases due to spin pumping phenomena, affecting the efficiency of spin injection.

Innovation Solution

A storage element configuration including a storage layer, a fixed magnetization layer, a spin barrier layer, and a spin absorption layer, where the spin barrier layer suppresses spin-polarized electron diffusion and is made of oxides, nitrides, or fluorides, and the spin absorption layer is a nonmagnetic metal layer, reducing the current needed for magnetization inversion and improving thermal stability.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Area of moving object

If address lines are made narrower to accommodate finer elements, then device density is improved, but current transmission capability deteriorates

Engineering Contradiction:

Improveelement sizeVSAvoidcurrent required for magnetization inversion

Core Design Contradiction:

Area of moving objectVSUse of energy by moving object

Solution Approach 1:

A spin absorption layer (nonmagnetic metal layer) is introduced as an intermediary component between the storage layer and the external environment. This layer absorbs spin-polarized electrons that are pumped into the storage layer, preventing their diffusion back and enhancing the spin injection efficiency. This intermediary structure enables effective magnetization inversion with reduced current requirements, resolving the contradiction between device miniaturization and current transmission capability.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The invention modifies the magnetic parameters of the storage layer by controlling its thickness and magnetic properties. By optimizing the storage layer thickness to be within a specific range (0.5-5 nm), the magnetization inversion can be achieved with lower current density. This parameter optimization allows finer elements to be used without proportionally increasing the current requirement, thus resolving the contradiction between element size reduction and current transmission.

Inventive Principle:

Principle #35Parameter changes

2Speed

If spin pumping phenomenon occurs to invert magnetization, then magnetization inversion is achieved, but Gilbert damping constant increases reducing spin injection efficiency

Engineering Contradiction:

Improvemagnetization inversion speedVSAvoidspin injection efficiency

Core Design Contradiction:

SpeedVSLoss of energy

Solution Approach 1:

The invention converts the harmful spin pumping phenomenon into a beneficial effect by introducing a spin absorption layer. The spin pumping that was previously causing energy loss and reduced efficiency is now harnessed to pump spin-polarized electrons into the storage layer, where they are absorbed by the spin absorption layer. This converts the energy loss into useful spin injection, enabling magnetization inversion while maintaining or improving spin injection efficiency.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

Solution Approach 2:

The invention replaces the traditional magnetic field-based magnetization inversion method with a spin-current-based mechanism. Instead of using external magnetic fields (mechanical approach), the system uses spin-polarized electron current to induce magnetization inversion through spin transfer torque. This substitution enables faster and more efficient magnetization switching, particularly in nanoscale devices where magnetic field methods become less effective.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

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 reduces the current required for magnetization inversion, enhances spin injection efficiency, and improves thermal stability, leading to lower power consumption and reliable information retention in MRAM devices.

Implementation Method 1

the spin barrier layer suppresses diffusion of spin-polarized electrons

Methodology Applied

Scientific EffectSpin-polarized electron diffusion: Diffusion

Implementation Method 2

The spin absorption layer includes a nonmagnetic metal layer causing the spin pumping phenomenon

Methodology Applied

Scientific EffectSpin pumping:

Implementation Method 3

by passing current in the direction perpendicular to the plane of the film to inject spin-polarized electrons

Methodology Applied

Scientific EffectSpin injection:

Implementation Method 4

the direction of magnetization in the storage layer can be changed

Methodology Applied

Scientific EffectMagnetization inversion:

Implementation Method 5

when information is read, magnetoresistive effect (MR effect) is used, in which the resistance changes according to the direction of magnetization

Methodology Applied

Scientific EffectMagnetoresistive effect: Magnetoresistance

Data Source

PatentUS11349067B2Storage element and memory

Publication Date: 2022.05.31 SONY GROUP CORP

AI summary

A storage element includes a storage layer, a fixed magnetization layer, a spin barrier layer, and a spin absorption layer. The storage layer stores information based on a magnetization state of a magnetic material. The fixed magnetization layer is provided for the storage layer through a tunnel insulating layer. The spin barrier layer suppresses diffusion of spin-polarized electrons and is provided on the side of the storage layer opposite the fixed magnetization layer. The spin absorption layer is formed of a nonmagnetic metal layer causing spin pumping and provided on the side of the spin barrier layer opposite the storage layer. A direction of magnetization in the storage layer is changed by passing current in a layering direction to inject spin-polarized electrons so that information is recorded in the storage layer and the spin barrier layer includes at least a material selected from oxides, nitrides, and fluorides.