Magnetoresistive Element Peripheral Tunnel Barrier Composition

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Solution Overview

Problem

Spin injection-type MRAMs face issues with dielectric breakdown and shorting due to electric stress on the tunnel barrier layer, especially in the peripheral areas, caused by processing damages and high inversion currents.

Innovation Solution

A magnetoresistive effect element with a tunnel barrier layer having a central portion with Mg and O as main components and a peripheral portion with B and O, which improves the voltage resistance and reliability by optimizing the width of the peripheral portion to between 0.7 nm and 12 nm, thereby reducing defects and enhancing the element's functionality.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a sufficiently large inversion current flows to reverse the magnetization direction, then the magnetic state switching is achieved, but dielectric breakdown occurs in the tunnel barrier layer due to electric stress

Engineering Contradiction:

Improvemagnetic state switching reliabilityVSAvoiddielectric breakdown

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The tunnel barrier layer is designed with different compositions in different regions: the central portion contains Mg and O as main components, while the peripheral portion contains B and O. This local quality differentiation allows the central region to provide low resistance for magnetic switching while the peripheral region with B and O enhances voltage resistance and prevents dielectric breakdown at the edges where processing damages occur.

Inventive Principle:

Principle #3Local quality

2Power

If the tunnel barrier layer is made thinner to reduce resistance, then switching efficiency improves, but voltage resistance decreases and dielectric breakdown risk increases

Engineering Contradiction:

Improveswitching efficiencyVSAvoidvoltage resistance

Core Design Contradiction:

PowerVSReliability

Solution Approach 1:

By creating a composite tunnel barrier layer with MgO in the central region and BO-containing material in the peripheral region, the invention achieves both low resistance and high voltage resistance simultaneously. The central MgO region provides efficient electron tunneling for switching, while the peripheral BO-containing region maintains voltage resistance even when the overall layer is thin.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The tunnel barrier layer combines different materials (MgO and BO-containing compound) in a composite structure. This composite material approach allows the layer to exhibit both low resistance properties from the MgO central region and high voltage resistance from the peripheral BO-containing region, resolving the contradiction between switching efficiency and voltage resistance.

Inventive Principle:

Principle #40Composite materials

3Ease of manufacture

If etching or processing is performed on the tunnel barrier layer, then device fabrication is enabled, but defects are introduced in the peripheral part leading to shorting

Engineering Contradiction:

Improvedevice fabricationVSAvoiddefect-free operation

Core Design Contradiction:

Ease of manufactureVSReliability

Solution Approach 1:

The peripheral portion of the tunnel barrier layer is pre-formed with B and O components before the final device fabrication steps. This beforehand cushioning creates a protective peripheral region that is more resistant to processing damages and etching defects, thereby preventing shorting while still allowing necessary fabrication processes to be performed.

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

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 solution effectively increases the dielectric breakdown voltage of the tunnel barrier layer, reducing the risk of dielectric breakdown and shorting, thus enhancing the reliability and performance of the magnetoresistive effect element.

Implementation Method 1

The second portion contains at least B (boron) and O (oxygen) as the main components thereof... effectively increases the dielectric breakdown voltage of the tunnel barrier layer

Methodology Applied

Scientific EffectDielectric breakdown resistance: Dielectric

Implementation Method 2

Spin injection-type Magnetic Random Access Memory (MRAM) provided with a magnetoresistive effect element (magnetoresistive element) having a ferromagnetic body as a memory element... operates by changing the magnetization direction of the magnetic layer using electric current injected into the magnetoresistive effect element

Methodology Applied

Scientific EffectSpin injection:

Implementation Method 3

memorizes information by maintaining the electric resistance of the magnetoresistive effect element in one of two high resistance state/low resistance states

Methodology Applied

Scientific EffectMagnetoresistive effect: Magnetoresistance

Data Source

PatentUS9196822B2Magnetoresistive effect element

Publication Date: 2015.11.24 KIOXIA CORP

AI summary

A magnetoresistive effect element in one or more embodiments of the present invention is provided with a memory layer with a variable magnetization direction having a magnetic anisotropy in a direction perpendicular to a film surface, a reference layer with an invariable magnetization direction having the magnetic anisotropy in a direction perpendicular to the film surface, and a tunnel barrier layer formed between the memory layer and the reference layer. The tunnel barrier layer has a first portion at the central part in the film surface and a second portion at a peripheral part. The second portion contains at least boron and oxygen.