Magnetic Tunneling Junction Thermal Stability via Perpendicular Magnetization

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Solution Overview

Problem

As pattern dimensions in magnetic memory devices decrease, it becomes challenging to maintain thermal stability in tunnel magneto resistance (TMR) effects, which are crucial for high-density, low-power, and nonvolatile memory solutions.

Innovation Solution

The implementation of a magnetic tunneling junction device with extrinsic perpendicular magnetization structures, including specific magnetic layers, perpendicular magnetization inducing layers, and a tunnel barrier, which enhance thermal stability by adjusting the oxygen affinity and resistivity of the layers to maintain effective magnetization properties.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Quantity of substance

If pattern dimensions are reduced to increase memory density, then memory density is improved, but thermal stability deteriorates

Engineering Contradiction:

Improvememory densityVSAvoidthermal stability

Core Design Contradiction:

Quantity of substanceVSReliability

Solution Approach 1:

The patent changes the magnetization orientation parameter from in-plane to perpendicular magnetization, and adjusts the thickness parameters of magnetic layers to achieve both high density and thermal stability. By modifying these physical parameters, the device maintains stability even at reduced dimensions.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent employs composite magnetic tunnel junction structures with multiple magnetic layers (CoFeB, CoFe, NiFe, CoFePt, CoFePd, CoFeCr, CoFeTb, CoFeGd, or CoFeNi) separated by non-magnetic spacer layers (Ru, Rh, Pd, Ag, Os, Ir, Pt, or Au). This composite structure enables both high memory density and improved thermal stability through controlled magnetic coupling.

Inventive Principle:

Principle #40Composite materials

2Reliability

If the thickness of magnetic layers is increased to improve thermal stability, then thermal stability is improved, but device complexity increases

Engineering Contradiction:

Improvethermal stabilityVSAvoidstructure complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent divides the magnetic structure into multiple thin magnetic layers separated by non-magnetic spacer layers. Each magnetic layer has a thickness of 1-30 nm, and the total magnetic thickness is controlled to achieve thermal stability without requiring a single thick magnetic layer, thus managing device complexity.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent transitions from in-plane magnetization to perpendicular magnetization, utilizing the vertical dimension for magnetization orientation. This dimensional change allows thermal stability to be achieved through vertical layer stacking rather than increasing lateral dimensions, thereby controlling device complexity.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

3Reliability

If multiple perpendicular magnetization inducing layers are added to enhance thermal stability, then thermal stability is improved, but manufacturing precision requirements increase

Engineering Contradiction:

Improvethermal stabilityVSAvoidlayer thickness control

Core Design Contradiction:

ReliabilityVSManufacturing precision

Solution Approach 1:

The patent specifies precise thickness ranges for each layer: magnetic layers (1-30 nm), non-magnetic spacer layers (0.5-5 nm), and tunnel barriers (1-3 nm). By establishing these parameter ranges, the patent balances thermal stability improvement with achievable manufacturing precision.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent applies different material compositions and thicknesses to different local regions of the device. For example, CoFeB layers are used in specific positions with specific thicknesses to provide localized perpendicular magnetic anisotropy, while other regions use different materials optimized for their specific functions, thereby managing manufacturing complexity.

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

This configuration improves the thermal stability of magnetic memory devices, allowing for increased total thickness of magnetic layers without reducing perpendicular anisotropy energy density, thus addressing the stability issues in reduced pattern dimensions.

Implementation Method 1

each magnetic layer has an oxygen affinity less than each perpendicular magnetization inducing layer

Methodology Applied

Scientific EffectOxygen diffusion: Diffusion

Implementation Method 2

a perpendicular magnetization inducing layer on the magnetic layer

Methodology Applied

Scientific EffectPerpendicular magnetization induction:

Implementation Method 3

An example data storing mechanism for a magnetic memory device is a tunnel magneto resistance (TMR) effect of a magnetic tunnel junction (MTJ)

Methodology Applied

Scientific EffectTunnel magneto resistance (TMR) effect:

Implementation Method 4

each perpendicular magnetization preserving layer has an oxygen affinity less than each perpendicular magnetization inducing layer

Methodology Applied

Scientific EffectOxygen affinity control:

Data Source

PatentUS9356228B2Magnetic tunneling junction devices, memories, memory systems, and electronic devices

Publication Date: 2016.05.31 SAMSUNG ELECTRONICS CO LTD

AI summary

Provided is a magnetic tunneling junction device including a first structure including a magnetic layer; a second structure including at least two extrinsic perpendicular magnetization structures, each including a magnetic layer and; a perpendicular magnetization inducing layer on the magnetic layer; and a tunnel barrier between the first and second structures.