Perpendicular Enhancement Layer in STT-MRAM for Thermal Stability

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Solution Overview

Problem

Spin transfer torque magnetic random access memory (STT-MRAM) devices face challenges in achieving thermal stability and cost-effective manufacturing as the size of perpendicular magnetic tunnel junctions (MTJs) is miniaturized, leading to degraded thermal stability and increased power consumption.

Innovation Solution

The introduction of a magnetic tunnel junction (MTJ) structure with a magnetic free layer and a magnetic reference layer separated by an insulating tunnel junction layer, incorporating perpendicular enhancement layers to improve anisotropy and thermal stability, and an anti-ferromagnetic coupling layer to stabilize the magnetic reference layer.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If the size of perpendicular magnetic tunnel junctions is miniaturized, then device scalability and integration density are improved, but thermal stability deteriorates

Engineering Contradiction:

Improvedevice scalabilityVSAvoidthermal stability

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

The magnetic reference layer is segmented into multiple sublayers (first magnetic reference sublayer, second magnetic reference sublayer, third magnetic reference sublayer) with different magnetization directions. This segmentation allows the system to maintain thermal stability through the combined effect of multiple layers while keeping the overall device size miniaturized for high scalability.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent employs composite magnetic layer structures combining ferromagnetic materials with perpendicular magnetic anisotropy in the free layer and in-plane magnetic anisotropy in the reference layers. This composite approach enables simultaneous achievement of thermal stability and miniaturization by leveraging the complementary magnetic properties of different material compositions.

Inventive Principle:

Principle #40Composite materials

2Productivity

If the size of perpendicular magnetic tunnel junctions is miniaturized, then device scalability is improved, but power consumption increases

Engineering Contradiction:

Improvedevice scalabilityVSAvoidpower consumption

Core Design Contradiction:

ProductivityVSUse of energy by moving object

Solution Approach 1:

The patent utilizes parameter changes in magnetic anisotropy by employing perpendicular magnetic anisotropy in the miniaturized free layer and in-plane magnetic anisotropy in the reference layers. This parameter optimization reduces the switching current required for miniaturized devices, thereby lowering power consumption while maintaining scalability.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent replaces conventional spin transfer torque mechanisms with a spin-orbit torque mechanism utilizing topological insulator materials. This substitution enables more efficient magnetization switching in miniaturized devices, reducing power consumption while maintaining high scalability.

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

The solution enhances the thermal stability and scalability of STT-MRAM devices, reducing power consumption while maintaining cost-effectiveness in manufacturing, thereby addressing the limitations of miniaturized MTJs.

Implementation Method 1

each of the first and second magnetic free layers having a variable magnetization direction perpendicular to the layer planes thereof

Methodology Applied

Scientific EffectPerpendicular magnetic anisotropy: Anisotropy

Implementation Method 2

an anti-ferromagnetic coupling layer to stabilize the magnetic reference layer

Methodology Applied

Scientific EffectAnti-ferromagnetic coupling: Magnetism

Implementation Method 3

Spin transfer torque magnetic random access memory (STT-MRAM) devices

Methodology Applied

Scientific EffectSpin transfer torque:

Data Source

PatentUS10727400B2Magnetic random access memory with perpendicular enhancement layer

Publication Date: 2020.07.28 AVALANCHE TECHNOLOGY INC

AI summary

The present invention is directed to a magnetic memory element including a magnetic free layer structure having a variable magnetization direction perpendicular to a layer plane thereof; a non-magnetic metal layer formed adjacent to the magnetic free layer structure; an oxide layer formed adjacent to the non-magnetic metal layer; an insulating tunnel junction layer formed adjacent to the magnetic free layer structure opposite the non-magnetic metal layer; a first magnetic reference layer formed adjacent to the insulating tunnel junction layer; a second magnetic reference layer separated from the first magnetic reference layer by a perpendicular enhancement layer; an antiferromagnetic coupling layer formed adjacent to the second magnetic reference layer; and a magnetic fixed layer structure formed adjacent to the antiferromagnetic coupling layer. The first and second magnetic reference layers have a first invariable magnetization direction substantially perpendicular to layer planes thereof. The magnetic fixed layer structure has a second invariable magnetization direction substantially opposite to the first invariable magnetization direction.