Magnetoresistive Memory Device Layer Thickness Variation

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Solution Overview

Problem

Magnetoresistive memory devices face challenges in maintaining consistent magnetic properties across multiple layers due to thermal treatments, leading to potential unintended switching of magnetization directions and reduced storage capacity.

Innovation Solution

The magnetoresistive memory device employs ferromagnetic layers with varying thicknesses to enhance tolerance against magnetic property deterioration, with ferromagnets in upper layers having larger thicknesses to maintain magnetization direction and conductors in different layers having thicknesses optimized for antiferromagnetic exchange coupling, ensuring consistent magnetic properties across layers.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If thermal treatment is applied to form magnetoresistive memory devices, then manufacturing process is enabled, but magnetic properties deteriorate and magnetization direction may switch unintentionally

Engineering Contradiction:

Improvemanufacturing processVSAvoidmagnetic properties consistency

Core Design Contradiction:

Ease of manufactureVSReliability

Solution Approach 1:

The patent applies different thicknesses to ferromagnetic layers in different layers of the magnetoresistive memory device. Specifically, the second ferromagnetic layer in upper layers has a greater thickness than in lower layers, creating local structural variation that compensates for thermal treatment effects and maintains consistent magnetic properties across all layers.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The patent changes the thickness parameter of the second ferromagnetic layer based on layer position. By increasing the thickness of the second ferromagnetic layer in upper layers compared to lower layers, the magnetic properties are adjusted to maintain stability throughout the device structure after thermal treatment.

Inventive Principle:

Principle #35Parameter changes

2Ease of manufacture

If uniform thickness is used for ferromagnetic layers across all layers, then manufacturing is simplified, but magnetic property variation occurs across layers

Engineering Contradiction:

Improvelayer fabricationVSAvoidmagnetic property consistency

Core Design Contradiction:

Ease of manufactureVSManufacturing precision

Solution Approach 1:

Instead of using uniform thickness, the patent implements local quality variation by making the second ferromagnetic layer thicker in upper layers compared to lower layers. This localized thickness adjustment ensures that each layer has the appropriate magnetic properties for its position, compensating for thermal treatment effects and maintaining overall consistency.

Inventive Principle:

Principle #3Local quality

3Reliability

If second ferromagnetic layer thickness is increased in upper layers, then tolerance against magnetic property deterioration is enhanced, but device structure becomes more complex

Engineering Contradiction:

Improvemagnetic property stabilityVSAvoidlayer structure

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent introduces asymmetry in the layer structure by making the second ferromagnetic layer thickness vary across different layers. This asymmetric design, where upper layers have thicker second ferromagnetic layers than lower layers, is specifically tailored to compensate for thermal treatment effects and maintain magnetic property consistency throughout the device.

Inventive Principle:

Principle #4Asymmetry

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 approach allows for the formation of magnetoresistive memory devices with improved magnetic properties, increased storage capacity, and reduced variation in magnetic properties across multiple layers, enhancing the reliability and capacity of the device.

Implementation Method 1

a magnetoresistive memory device capable of storing data using a magnetoresistive effect is known

Methodology Applied

Scientific EffectMagnetoresistive effect: Magnetoresistance

Implementation Method 2

conductors in different layers having thicknesses optimized for antiferromagnetic exchange coupling, ensuring consistent magnetic properties across layers

Methodology Applied

Scientific EffectAntiferromagnetic exchange coupling: Magnetism

Data Source

PatentUS11502125B2Magnetoresistive memory device

Publication Date: 2022.11.15 KIOXIA CORP

AI summary

A magnetoresistive memory device according to one embodiment includes: first and second layer stacks, each of which includes: a first ferromagnetic layer having a magnetization directed in a first direction; a non-magnetic first conductive layer above the first ferromagnetic layer, a second ferromagnetic layer provided above the first conductive layer and having a magnetization directed in a second direction different from the first direction, a first insulating layer on an upper surface of the second ferromagnetic layer, and a third ferromagnetic layer above the first insulating layer. The second ferromagnetic layer of the second layer stack is thicker than the second ferromagnetic layer of the first layer stack.