DMTJ Magnetic Memory Structure for Canceling Edge Magnetostatic Fields

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Solution Overview

Problem

Magnetic memory devices face challenges in reducing the switching current required for magnetization direction changes due to high in-plane magnetostatic fields at the edges of free magnetic layers, which affects the efficiency and reliability of data storage.

Innovation Solution

The magnetic memory device design incorporates a stack structure with specific layer arrangements and dimensions, including a first reference magnetic layer, tunnel barrier layers, and a free magnetic layer, where the in-plane magnetostatic field from the reference magnetic layers is minimized to less than 500 Oe, reducing the fringing field and switching current.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If conventional magnetic memory device structure is used, then magnetization switching function is achieved, but high in-plane magnetostatic field at edges increases switching current requirement

Engineering Contradiction:

Improveswitching currentVSAvoidin-plane magnetostatic field

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent applies the 'Blessing in disguise' principle by introducing a compensating reference magnetic layer that generates a magnetostatic field to counteract the harmful in-plane magnetostatic field at the edges of the free magnetic layer. The harmful field from the first reference magnetic layer is converted into a beneficial effect by using a second reference magnetic layer with opposite magnetization direction to cancel it out, reducing the net in-plane field to less than 500 Oe and thereby lowering the switching current requirement.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

Solution Approach 2:

The patent applies the 'Parameter changes' principle by modifying the magnetization direction parameter of the reference magnetic layers. By setting the second reference magnetic layer's magnetization direction to be opposite to the first reference magnetic layer, the patent changes the magnetic field parameters to achieve cancellation of in-plane magnetostatic fields at the edges of the free magnetic layer.

Inventive Principle:

Principle #35Parameter changes

2Productivity

If device width is reduced to increase storage density, then storage capacity improves, but edge effects and magnetostatic field concentration increase

Engineering Contradiction:

Improvestorage densityVSAvoidedge magnetostatic field

Core Design Contradiction:

ProductivityVSObject-affected harmful factors

Solution Approach 1:

The patent applies the 'Blessing in disguise' principle to address edge effects in scaled-down devices. By introducing a second reference magnetic layer with opposite magnetization, the harmful concentrated magnetostatic field at the edges of narrow free magnetic layers is converted into a beneficial cancellation effect, reducing the net in-plane field and enabling reliable operation at smaller dimensions for increased storage density.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

Solution Approach 2:

The patent applies the 'Composite materials' principle by creating a composite magnetic stack structure consisting of multiple magnetic layers (first reference magnetic layer, free magnetic layer, second reference magnetic layer) with different magnetization directions. This composite structure enables the free magnetic layer to benefit from both reference layers' fields, canceling edge effects while maintaining the necessary magnetization switching functionality.

Inventive Principle:

Principle #40Composite materials

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 design reduces the switching current and enhances the efficiency and reliability of data storage by minimizing the in-plane magnetostatic field at the edges of the free magnetic layer, improving the overall performance of magnetic memory devices.

Implementation Method 1

a magnitude of an in-plane magnetostatic field from the first reference magnetic layer at an edge of the free magnetic layer may be less than about 500 Oe

Methodology Applied

Scientific EffectMagnetostatic field: Magnetic Field

Implementation Method 2

a first tunnel barrier layer on the first reference layer, a second tunnel barrier layer

Methodology Applied

Scientific EffectTunneling:

Data Source

PatentUS10062732B2DMTJ structure for sub-25NM designs with cancelled flowering field effects

Publication Date: 2018.08.28 SAMSUNG ELECTRONICS CO LTD

AI summary

A magnetic memory device comprises a first reference magnetic layer, a first tunnel barrier layer, a second tunnel barrier layer, and a free magnetic layer disposed between the first tunnel barrier layer and the second tunnel barrier layer. A magnitude of an in-plane magnetostatic field from the first reference magnetic layer at an edge of the free magnetic layer is less than about 500 Oe. One embodiment comprises a second reference magnetic layer on the second tunnel barrier layer in which the first reference magnetic layer, the first tunnel barrier layer, the free magnetic layer, the second tunnel barrier layer and the second reference magnetic layer are arranged as a stack, and in which a width of the first tunnel barrier layer, the free magnetic layer, the second tunnel barrier and the second reference magnetic layer in a second direction is less than about 30 nm.