Magnetic Tunneling Junction Seed Layer for High-Temperature TMR Stability

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Solution Overview

Problem

Existing magnetic tunneling junction devices and memory devices face challenges in achieving high tunneling magnetoresistance (TMR) ratios and exchange fields (Hex), with crystal structure collisions during high-temperature manufacturing processes leading to deteriorated crystallinity and reduced performance.

Innovation Solution

Incorporation of amorphous seed and anti-crystallized layers, along with polarization enhancing layers, to maintain crystal quality during high-temperature heat treatments, using materials like CoFeX, YCoFeB, and CoFeB, and employing synthetic antiferromagnet structures to stabilize magnetization directions.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If high-temperature heat treatment is performed to improve crystal quality, then TMR ratio is improved, but crystal structure collision occurs leading to deteriorated crystallinity

Engineering Contradiction:

Improvecrystal qualityVSAvoidcrystallinity

Core Design Contradiction:

Manufacturing precisionVSReliability

Solution Approach 1:

An amorphous seed layer is introduced as an intermediary between the substrate and the crystalline magnetic layers. This amorphous layer acts as a buffer that prevents crystal structure collision during high-temperature heat treatment, allowing the crystalline layers to maintain their quality without direct interaction that would cause deterioration.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The invention changes the physical state parameter of the seed layer from crystalline to amorphous. This parameter change allows the seed layer to remain stable during high-temperature heat treatment without undergoing crystal structure transformations that would collide with adjacent crystalline layers, thereby enabling improved heat treatment processes.

Inventive Principle:

Principle #35Parameter changes

2Reliability

If amorphous seed layer is used to prevent crystal collision, then crystallinity is maintained, but device complexity increases

Engineering Contradiction:

ImprovecrystallinityVSAvoidlayer structure

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The magnetic tunneling junction is segmented into distinct functional layers with the amorphous seed layer serving as a separate, dedicated component. This segmentation allows each layer to be optimized independently - the amorphous seed layer for preventing crystal collision, and the crystalline layers for magnetic functionality - thereby justifying the increased structural complexity.

Inventive Principle:

Principle #1Segmentation

3Manufacturing precision

If heat treatment temperature is increased to improve TMR ratio, then tunneling magnetoresistance is improved, but manufacturing process difficulty increases

Engineering Contradiction:

ImproveTMR ratioVSAvoidheat treatment process

Core Design Contradiction:

Manufacturing precisionVSEase of manufacture

Solution Approach 1:

The amorphous seed layer serves as a protective intermediary that enables higher heat treatment temperatures. By preventing crystal structure collision, it allows the process to operate in a temperature regime that improves TMR ratio without causing the crystallinity deterioration that would otherwise limit the maximum usable temperature.

Inventive Principle:

Principle #24Intermediary (Mediator)

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

Enhances TMR ratios and Hex by maintaining crystal integrity, allowing for higher resistance differences and improved operating stability under external magnetic fields, thus improving device performance.

Implementation Method 1

The seed layer includes at least one amorphous material selected from CoFeX and CoFeXTa... The seed layer and the anti-crystallized layer may be maintained in an amorphous state at a temperature of about 300° C. to about 500° C.

Methodology Applied

Scientific EffectAmorphous state stability:

Implementation Method 2

a tunnel barrier layer between the pinned layer and the free layer... a tunneling magnetoresistance (TMR) ratio having a high value

Methodology Applied

Scientific EffectTunneling magnetoresistance: Magnetoresistance

Implementation Method 3

employing synthetic antiferromagnet structures to stabilize magnetization directions

Methodology Applied

Scientific EffectExchange coupling:

Implementation Method 4

performing a heat treatment for crystallizing the pinned layer... The heat treatment may be performed at a temperature of 300° C. to 500° C.

Methodology Applied

Scientific EffectHeat treatment: Heat Treatment

Data Source

PatentUS20250344609A1Magnetic tunneling junction device and memory device including the same

Publication Date: 2025.11.06 SAMSUNG ELECTRONICS CO LTD

AI summary

Provided are a magnetic tunneling junction device having a relatively high tunneling magnetoresistance (TMR) ratio; and a memory device including the magnetic tunneling junction device. The magnetic tunneling junction device includes: a pinned layer having a first surface and a second surface opposite the first surface; a seed layer disposed in contact with the first surface of the pinned layer; a free layer disposed to face the second surface of the pinned layer; and a tunnel barrier layer disposed between the pinned layer and the free layer, wherein the seed layer includes at least one amorphous material selected from CoFeX and CoFeXTa, and the X includes at least one element selected from niobium (Nb), molybdenum (Mo), tungsten (W), chromium (Cr), zirconium (Zr), and hafnium (Hf). The seed layer may not include boron.