MRAM Programming via Magnetic Field-Assisted Spin Transfer

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Solution Overview

Problem

Magnetic random access memory (MRAM) programming requires high current densities to change magnetic resistance, leading to increased power consumption and electron migration, affecting operating efficiency and quality.

Innovation Solution

A programming method for MRAM that reduces the first electron current by applying an additional magnetic field, allowing the magnetic free layer to change direction with lower current density, thereby reducing power consumption and preventing electron migration.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If high current density is applied to change magnetic resistance during programming, then the magnetic state can be effectively switched, but power consumption increases and electron migration occurs

Engineering Contradiction:

Improvemagnetic state switching effectivenessVSAvoidpower consumption

Core Design Contradiction:

ReliabilityVSUse of energy by moving object

Solution Approach 1:

The patent introduces a magnetic field as an intermediary to assist the electron current in switching the magnetic state. The magnetic field generated by the current flowing through the tunnel barrier acts as a mediator that works together with the spin-polarized electrons to change the magnetic resistance, allowing lower current density to achieve the same switching effectiveness and thereby reducing power consumption

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent changes the programming mechanism from relying solely on high current density to using a combination of magnetic field and reduced current density. By altering the physical parameters of the programming process (introducing magnetic field component and reducing current density), the patent achieves effective magnetic state switching while reducing power consumption and preventing electron migration

Inventive Principle:

Principle #35Parameter changes

2Reliability

If high current density is applied to change magnetic resistance during programming, then the magnetic state can be effectively switched, but electron migration occurs affecting memory quality

Engineering Contradiction:

Improvemagnetic state switching effectivenessVSAvoidelectron migration

Core Design Contradiction:

ReliabilityVSObject-generated harmful factors

Solution Approach 1:

The magnetic field acts as an intermediary that reduces the burden on electron current alone. By sharing the switching task between the magnetic field and the electron current, the required current density is reduced to a level that does not cause electron migration, thereby maintaining magnetic state switching effectiveness while eliminating the harmful effect of electron migration

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent converts the harmful effect of high current density (which causes electron migration) into a beneficial approach by using the magnetic field generated by a controlled current to assist switching. The current is maintained at a level that generates useful magnetic field effect without reaching the threshold that causes electron migration, thus converting the potential harm into a beneficial dual-mechanism switching approach

Inventive Principle:

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

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

The method significantly reduces power consumption and enhances operating efficiency by lowering the electron current density during programming, improving the overall performance of MRAM.

Implementation Method 1

an additional magnetic field is applied onto the magnetic free layer

Methodology Applied

Scientific EffectMagnetic field: Magnetic Field

Implementation Method 2

data are programmed through the spin-transferring of current or electron current

Methodology Applied

Scientific EffectSpin transfer:

Data Source

PatentUS7508702B2Programming method of magnetic random access memory

Publication Date: 2009.03.24 MACRONIX INTERNATIONAL CO LTD

AI summary

A programming method of a magnetic random access memory (MRAM) is provided. The magnetic random access memory includes a first magnetic pinned layer, a second magnetic pinned layer and a magnetic free layer. The first magnetic pinned layer is pinned at a first magnetic direction. The second magnetic pinned layer is pinned at a second magnetic direction. The magnetic free layer is magnetized into the first magnetic direction or the second magnetic direction. The programming method includes the following the steps. In the step (a), an additional magnetic field is applied onto the magnetic free layer. In the step (b), a first electron current is emitted through the magnetic free layer to magnetize the magnetic free layer into the first magnetic direction or the second magnetic direction.