MRAM Magnetic Recording Layer In-Plane Current Flow

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Solution Overview

Problem

Conventional MRAM technologies face challenges in reducing write current with miniaturization, leading to increased power consumption and potential deterioration of the tunnel barrier layer during data writing, especially in smaller memory cells.

Innovation Solution

The proposed MRAM design incorporates a magnetic recording layer with a magnetization switching region and fixed regions forming a three-way intersection, allowing write currents to flow planarly within the layer, reducing the need for high current densities and minimizing the impact on the tunnel barrier layer by separating write and read current paths.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If conventional write methods (asteroid method or toggle method) are used, then data writing is achieved, but the magnetic switching field increases with miniaturization of the memory cell, causing write current to increase

Engineering Contradiction:

Improvememory cell sizeVSAvoidwrite current

Core Design Contradiction:

Manufacturing precisionVSUse of energy by moving object

Solution Approach 1:

The patent changes the dimension of current flow from perpendicular to the film plane (CPP method) to within the film plane (SIC method). By making the current flow in-plane through the magnetic recording layer, the write current does not need to pass through the tunnel barrier layer, enabling write current to decrease with miniaturization rather than increase

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

Solution Approach 2:

The magnetic recording layer is divided into a magnetization switching region and two magnetization fixed regions. This segmentation allows the current to flow through fixed regions without switching magnetization, reducing the required current density and enabling scalable miniaturization

Inventive Principle:

Principle #1Segmentation

2Productivity

If high current density is applied perpendicular to the film plane for magnetization switching, then data writing is achieved, but the tunnel barrier layer deteriorates

Engineering Contradiction:

Improvedata writing speedVSAvoidtunnel barrier layer integrity

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

The patent extracts the write current path from the tunnel barrier layer by using in-plane current flow. The write current now flows through the magnetic recording layer parallel to the tunnel barrier layer, completely separating the write current path from the read current path that passes through the tunnel barrier layer

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The magnetic recording layer acts as an intermediary that carries the write current in-plane. Instead of forcing current through the tunnel barrier layer, the patent uses the magnetic recording layer as a current carrier that can support high current densities without deteriorating the tunnel barrier layer

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

This approach simplifies the control of write currents, reduces power consumption, and prevents tunnel barrier layer deterioration, enabling efficient data writing and reading while maintaining memory cell selectivity and scalability.

Implementation Method 1

a spin-polarized current is injected to a ferromagnetic conductor, and direct interaction between spin of conduction electrons of the current and magnetic moment of the conductor causes the magnetization to be switched

Methodology Applied

Scientific EffectSpin transfer magnetization switching:

Implementation Method 2

a magnetoresistance element that exhibits a 'magnetoresistance effect' such as TMR (Tunnel MagnetoResistance) effect is utilized

Methodology Applied

Scientific EffectMagnetoresistance effect: Magnetoresistance

Implementation Method 3

a magnetoresistance element that exhibits a 'magnetoresistance effect' such as TMR (Tunnel MagnetoResistance) effect is utilized

Methodology Applied

Scientific EffectTunnel MagnetoResistance effect:

Data Source

PatentUS7848137B2MRAM and data read/write method for MRAM

Publication Date: 2010.12.07 NEC CORP

AI summary

An MRAM according to the present invention is provided with a magnetic recording layer being a ferromagnetic layer and a pinned layer connected to the magnetic recording layer through a nonmagnetic layer. The magnetic recording layer includes a magnetization switching region, a first magnetization fixed region and a second magnetization fixed region. The magnetization switching region has reversible magnetization and overlaps with the pinned layer. The first magnetization fixed region and the second magnetization fixed region are both connected to the same one end of the magnetization switching region. Also, the first magnetization fixed region and the second magnetization fixed region respectively have first fixed magnetization and second fixed magnetization whose directions are fixed. One of the first fixed magnetization and the second fixed magnetization is fixed in a direction toward the above-mentioned one end, and the other is fixed in a direction away from the above-mentioned one end.