MTJ Shielding Structure for External Magnetic Field Deflection

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Solution Overview

Problem

Magnetic tunnel junction (MTJ) devices in MRAM and other applications face challenges in enhancing electrical characteristics and protecting against external magnetic field turbulence, which affects their stability and durability.

Innovation Solution

A method for manufacturing a magnetic memory device with a magnetic tunnel junction (MTJ) unit that includes a shielding element with a soft magnetic material, strategically positioned to deviate external magnetic fields, thereby improving magnetic coercivity and reducing reflow bit error rates, and incorporating a spacer to protect against corrosion and material diffusion.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a magnetic memory device is designed without a shielding layer, then the device structure remains simple and manufacturing is easier, but the device is vulnerable to external magnetic field turbulence which degrades electrical characteristics and performance

Engineering Contradiction:

Improveelectrical characteristicsVSAvoidstructure

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent implements a nested shielding structure where the inner dielectric film, magnetic film, and outer dielectric film are arranged in concentric layers surrounding the MTJ unit. This nested configuration provides effective magnetic field shielding while maintaining a compact and integrated device structure, resolving the contradiction between reliability improvement and structural complexity.

Inventive Principle:

Principle #7Nested doll (Nesting)

Solution Approach 2:

The shielding layer acts as an intermediary component between the external environment and the MTJ unit. The magnetic film within the shielding layer specifically targets and deflects external magnetic field turbulence, protecting the sensitive MTJ unit without requiring fundamental changes to the core memory structure.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Reliability

If a shielding layer with multiple films is added to protect against magnetic field turbulence, then electrical characteristics are improved, but manufacturing complexity and process difficulty increase

Engineering Contradiction:

ImproveperformanceVSAvoidmanufacturing process

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

The shielding layer is segmented into three distinct functional films: an inner dielectric film for structural support and field distribution, a magnetic film for active magnetic field deflection, and an outer dielectric film for protection and integration. This segmentation allows each layer to be optimized independently for its specific function while simplifying the overall manufacturing process through modular deposition techniques.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The shielding layer employs a composite structure combining dielectric and magnetic materials in a layered configuration. This composite approach leverages the complementary properties of different materials - the dielectric films provide structural stability and field distribution, while the magnetic film provides active shielding - achieving superior performance without requiring a single complex material system.

Inventive Principle:

Principle #40Composite materials

3Device complexity

If the MTJ unit is exposed to external magnetic field turbulence, then the device structure remains uncomplicated, but the electrical characteristics and performance deteriorate

Engineering Contradiction:

ImprovestructureVSAvoidmagnetic field turbulence

Core Design Contradiction:

Device complexityVSObject-affected harmful factors

Solution Approach 1:

The patent converts the harmful effect of external magnetic field turbulence into a beneficial shielding mechanism. The magnetic film in the shielding layer is designed to interact with external magnetic fields, deflecting and redistributing them around the MTJ unit. This transforms the previously harmful magnetic field exposure into a controlled interaction that protects the device while maintaining structural simplicity.

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 solution effectively reduces the impact of external magnetic fields on MTJ elements, enhancing the stability and durability of magnetic memory devices by improving magnetic coercivity and reducing reflow bit error rates, while also preventing short-circuiting due to the shielding element's positioning.

Implementation Method 1

a magnetic memory device with a magnetic tunnel junction (MTJ) unit is designed to include a shielding layer comprising an inner dielectric film, a magnetic film, and an outer dielectric film, providing enhanced protection against external magnetic field turbulence

Methodology Applied

Scientific EffectMagnetic field deviation: Magnetic Field

Data Source

PatentUS20230345842A1Magnetic memory device and method for manufacturing the same

Publication Date: 2023.10.26 TAIWAN SEMICONDUCTOR MANUFACTURING CO LTD

AI summary

A memory device includes a memory unit and a shielding element disposed on the memory unit. The memory unit includes a bottom electrode, a memory element disposed on the bottom electrode, and a top electrode disposed on the memory element. The shielding element is disposed on the memory unit to deviate an external magnetic field away from the memory element.