Magnetic Storage Device Coercivity Hierarchy

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Magnetic storage devices using magnetoresistive effect elements face challenges in accurately reading data due to temperature-dependent characteristics and instability in resistance states of reference cells, leading to increased complexity and area requirements.

Innovation Solution

The implementation of MTJ elements in both memory and reference cells, with specific configurations of magnetic layers and coercivity adjustments, allows for stable operation and reduced temperature dependence by maintaining the magnetization orientation of the free layer parallel to the reference layer, thereby generating a stable reference current.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If magnetoresistive effect elements are used in magnetic storage devices, then data storage capability is achieved, but temperature-dependent characteristics and instability in resistance states occur

Engineering Contradiction:

Improvestability of resistance statesVSAvoidtemperature dependence

Core Design Contradiction:

ReliabilityVSTemperature

Solution Approach 1:

The patent applies parameter changes by carefully controlling the coercivity values of different magnetic layers (first coercivity Hc1, second coercivity Hc2, third coercivity Hc3) to create a hierarchical structure where each layer has distinct magnetic stability characteristics. This parameter differentiation enables the system to maintain stable resistance states across temperature variations while achieving reliable data storage.

Inventive Principle:

Principle #35Parameter changes

2Measurement precision

If reference cells are used to generate reference current, then data reading accuracy is improved, but device complexity and area requirements increase

Engineering Contradiction:

Improvedata reading accuracyVSAvoidcomplexity of reference cell configuration

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The patent merges the reference cell functionality into the existing magnetoresistive effect element structure by using the same three-layer magnetic configuration (with coercivities Hc1, Hc2, Hc3) for both memory and reference cells. This unified approach generates stable reference currents without requiring separate, complex reference cell circuits, thereby maintaining data reading accuracy while reducing device complexity.

Inventive Principle:

Principle #5Merging (Combining)

3Object-affected harmful factors

If magnetization orientation is maintained parallel to reference layer, then temperature sensitivity is reduced, but manufacturing precision requirements increase

Engineering Contradiction:

Improvetemperature sensitivityVSAvoidcoercivity control precision

Core Design Contradiction:

Object-affected harmful factorsVSManufacturing precision

Solution Approach 1:

The patent applies local quality by assigning different coercivity characteristics to specific magnetic layers: the first magnetic layer has coercivity Hc1, the second has Hc2, and the third has Hc3, where each layer's coercivity is specifically tailored to its functional role. This localized differentiation of magnetic properties enables the system to reduce temperature sensitivity through controlled magnetization orientation while managing manufacturing precision requirements through hierarchical coercivity design.

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 enables downsized reference cells with improved stability and reduced temperature sensitivity, allowing for accurate data reading without the need for potential adjustments, while maintaining the same process complexity as the MTJ elements used in memory cells.

Implementation Method 1

A magnetic storage device using a magnetoresistive effect element is known, for example

Methodology Applied

Scientific EffectMagnetoresistive effect: Magnetoresistance

Implementation Method 2

The first magnetoresistive effect element includes a first magnetic layer having a first coercivity, a second magnetic layer having a second coercivity higher than the first coercivity, and a third magnetic layer having a third coercivity higher than the second coercivity

Methodology Applied

Scientific EffectCoercivity: Magnetic Hysteresis

Data Source

PatentUS9576632B2Magnetic storage device

Publication Date: 2017.02.21 KIOXIA CORP

AI summary

A magnetic storage device of one embodiment includes a first and second magnetoresistive effect elements. The first magnetoresistive element includes a first magnetic layer having a first coercivity, a second magnetic layer having a second coercivity higher than the first coercivity, and a third magnetic layer having a third coercivity higher than the second coercivity. Magnetization orientations of the second and third magnetic layers are antiparallel. The second magnetoresistive effect element includes a fourth magnetic layer having a fourth coercivity, a fifth magnetic layer having a fifth coercivity higher than the fourth coercivity, and a sixth magnetic layer having a sixth coercivity higher than the fifth coercivity. Magnetization orientations of the fifth and sixth magnetic layers are parallel.