Magnetoresistive Element Edge Treatment for MTJ Short Circuit Prevention

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Solution Overview

Problem

Magnetic Tunnel Junction (MTJ) elements face short circuits and degradation in magnetic characteristics due to re-attached substances during processing, which hinder data writing and degrade spin injection efficiency.

Innovation Solution

Injecting specific elements like He, C, N, O, F, Ne, Ti, V, Cu, Al, Si, P, S, Cl, Ar, Ga, Ge, As, Kr, Zr, In, Sn, Sb, or Bi into the edge portions of magnetic layers to deactivate magnetization and prevent short circuits, while oxidizing re-attached substances to maintain magnetic characteristics.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If over-etching is employed to process MTJ element into pillar shape, then the substrate electrode can be properly etched, but re-attached electroconductive substance causes short circuit between memory layer and reference layer

Engineering Contradiction:

Improvepillar shape processingVSAvoidshort circuit prevention

Core Design Contradiction:

Manufacturing precisionVSReliability

Solution Approach 1:

An insulating layer is introduced as an intermediary substance between the memory layer and reference layer. This insulating layer prevents direct electrical contact (short circuit) between the two magnetic layers while allowing the etching process to proceed with over-etching to form the pillar shape. The insulating layer acts as a mediator that resolves the conflict between achieving proper pillar formation and preventing short circuits.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The harmful re-attached electroconductive substance is removed from the side wall of the MTJ element through selective etching. By extracting this conductive material that causes short circuits, the patent maintains the benefits of over-etching for pillar shape formation while eliminating the short circuit problem.

Inventive Principle:

Principle #2Taking out (Extraction)

2Reliability

If re-attached substance is removed to prevent short circuit, then short circuit is prevented, but magnetic characteristics of magnetic layers are degraded

Engineering Contradiction:

Improveshort circuit preventionVSAvoidmagnetic characteristics

Core Design Contradiction:

ReliabilityVSManufacturing precision

Solution Approach 1:

The patent applies different treatments to different regions: the insulating layer is specifically positioned at the critical interface between memory and reference layers to prevent short circuits, while the bulk magnetic layers are protected from aggressive etching that would degrade their magnetic characteristics. This localized approach maintains magnetic properties where needed while preventing short circuits where necessary.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The insulating layer serves as a protective intermediary that allows the removal of conductive substances without directly exposing the magnetic layers to harsh etching conditions. It mediates between the need to remove conductive material and the need to preserve magnetic characteristics.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Reliability

If element injection is performed to deactivate magnetization, then short circuit is prevented and magnetic characteristics are maintained, but process complexity increases

Engineering Contradiction:

Improveshort circuit prevention with magnetic characteristic maintenanceVSAvoidmanufacturing process

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent combines multiple functions into the element injection process: the injected elements simultaneously deactivate magnetization in the reference layer (preventing unwanted magnetic interactions), prevent short circuits by modifying the side wall properties, and maintain magnetic characteristics of the memory layer. This merging of functions reduces overall process complexity despite the sophistication of the injection technique.

Inventive Principle:

Principle #5Merging (Combining)

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

Prevents short circuits and degradation of magnetic characteristics, thereby enhancing the spin injection efficiency and maintaining the magnetic properties of MTJ elements.

Implementation Method 1

at least one element selected from the group consisting of He, C, N, O, F, Ne, Ti, V, Cu, Al, Si, P, S, Cl, Ar, Ga, Ge, As, Kr, Zr, In, Sn, Sb, and Bi is injected into edge portions of the first and second magnetic layers

Methodology Applied

Scientific EffectMagnetization deactivation: Magnetism

Implementation Method 2

the re-attached substance causes a short circuit of the memory layer and the reference layer

Methodology Applied

Scientific EffectOxidation: Oxidation

Data Source

PatentUS9166151B2Magnetoresistive element and manufacturing method of the same

Publication Date: 2015.10.20 KIOXIA CORP

AI summary

A magnetoresistive element has a magnetic layer, an insulating layer and a magnetic layer, which are laminated on a base electrode, and side walls of the magnetic layers that are formed when the magnetic layers are processed. At least one element selected from the group of consisting He, C, N, O, F, Ne, Ti, V, Cu, Al, Si, P, S, Cl, Ar, Ge, As, Kr, Zr, In, Sn, Sb, Pb and Bi is injected into the side walls and edge portions of the magnetic layers to improve the magnetic characteristics of the first and second magnetic layers.