Magnetic Memory Element Nonmagnetic Dielectric Layer Magnetization Inversion

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Solution Overview

Problem

Magnetization inversion in magnetic memory devices by spin injection requires high current densities and is inefficient due to peripheral damage and uneven magnetic characteristics, leading to incomplete magnetization inversion.

Innovation Solution

A magnetic memory element with a layer structure comprising a pinned layer, a nonmagnetic dielectric layer, and a free layer, where the nonmagnetic dielectric layer covers the entire surface of the free layer, focusing electron flow to the center for efficient magnetization inversion, thereby reducing the required current and enhancing magnetic characteristics.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If spin injection method is used for magnetization inversion, then magnetization can be inverted in the memory layer, but high current density (about 1×10 MA/cm2) is required which causes wiring restrictions and increases device complexity

Engineering Contradiction:

Improvemagnetization inversion capabilityVSAvoidwiring restriction

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent applies local quality by creating a nonmagnetic dielectric layer with varying thickness across the memory layer surface. The thinner region is positioned at the center of the memory layer where spin-polarized electrons are most effectively injected, while peripheral regions have thicker dielectric layers. This spatial variation in dielectric thickness concentrates the magnetization inversion effect at the center, reducing the overall current density requirement while maintaining inversion capability.

Inventive Principle:

Principle #3Local quality

2Reliability

If current is applied to peripheral part of memory layer, then magnetization inversion may occur in peripheral regions, but peripheral damage during processing deteriorates magnetic characteristics and prevents effective inversion

Engineering Contradiction:

Improvemagnetization inversionVSAvoidperipheral damage

Core Design Contradiction:

ReliabilityVSManufacturing precision

Solution Approach 1:

The nonmagnetic dielectric layer is designed with non-uniform thickness to create different magnetic characteristics in different regions. The thinner dielectric region at the center provides optimal conditions for spin injection and magnetization inversion, while the thicker peripheral regions compensate for processing damage by providing better protection and reducing the impact of edge effects on overall device performance.

Inventive Principle:

Principle #3Local quality

3Reliability

If uniform current distribution is used, then entire memory layer is addressed, but inversion energy in center part is higher than peripheral part resulting in incomplete inversion

Engineering Contradiction:

Improvecomplete magnetization inversionVSAvoidinversion energy

Core Design Contradiction:

ReliabilityVSUse of energy by moving object

Solution Approach 1:

The patent creates a non-uniform dielectric layer structure where the thickness varies spatially across the memory layer. This results in non-uniform current density distribution during spin injection, with higher current density concentrated at the center region where the dielectric is thinner. This localized current enhancement compensates for the higher inversion energy requirement at the center, enabling complete magnetization inversion across the entire memory layer.

Inventive Principle:

Principle #3Local quality

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 enables low-current rewriting of information with improved magnetic characteristics by intensively injecting spin-polarized electrons to the center of the memory layer, minimizing peripheral damage effects and increasing inversion efficiency.

Implementation Method 1

the current needed for magnetization inversion of the memory layer is made smaller and thus this method can be said to be a memory method suitable for a nonvolatile magnetic memory device with high capacity

Methodology Applied

Scientific EffectSpin injection:

Implementation Method 2

STT-MRAM (Spin Transfer Torque-MRAM) using a method for inverting the magnetization direction of a memory layer by flowing spin-polarized electrons to the magnetic layer

Methodology Applied

Scientific EffectSpin transfer torque:

Implementation Method 3

the magnetization direction of the memory layer (FL) has a reversible magnetization direction in response to the current through the layer structure

Methodology Applied

Scientific EffectMagnetization inversion:

Data Source

PatentUS7932573B2Magnetic memory element and magnetic memory device

Publication Date: 2011.04.26 RENESAS ELECTRONICS CORP

AI summary

A magnetic memory element having a layer structure containing a fixing layer (pinned layer: PL) having a magnetization direction fixed unidirectionally, a nonmagnetic dielectric layer (TN1) in contact with the fixing layer (PL), and a memory layer (free layer: FL) having a first surface in contact with the nonmagnetic dielectric layer (TN1) and a second surface on the opposite to the first surface, the magnetization direction of the memory layer (FL) having a reversible magnetization direction in response to the current through the layer structure. The entire surface of the first surface of the memory layer (FL) is covered with the nonmagnetic dielectric layer (TN1) and in the joint surface of the nonmagnetic dielectric layer (TN1) and the fixing layer (PL), the first surface of the nonmagnetic dielectric layer (TN1) is exposed in a manner of surrounding the joint surface.