TMR Element Base Layer Stress Relief for Tunnel Barrier Flatness

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Solution Overview

Problem

The flatness of the tunnel barrier layer in tunnel magnetoresistive effect (TMR) elements is compromised by surface irregularities on via interconnects, leading to reduced magnetoresistive ratio and durability due to non-uniform voltage application and increased risk of breakdown.

Innovation Solution

Incorporating a base layer with a stress relieving region, such as cracks, on the surface of via interconnects, which improves the flatness of the tunnel barrier layer by relieving stress caused by recesses and protrusions, and using an interlayer insulation layer to cover side surfaces, ensuring uniform voltage application and enhanced durability.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If a base layer is disposed directly on the upper surface of a via interconnect part with recesses and protrusions, then the manufacturing process is simplified, but the flatness of the tunnel barrier layer is decreased due to stress from surface irregularities

Engineering Contradiction:

Improvesimplification of base layer deposition processVSAvoidflatness of tunnel barrier layer

Core Design Contradiction:

Ease of manufactureVSManufacturing precision

Solution Approach 1:

An interlayer insulation layer is introduced as an intermediary component between the base layer and the tunnel barrier layer. This mediator layer fills the recesses and covers the protrusions on the base layer surface, creating a flat upper surface that enables subsequent deposition of a high-quality tunnel barrier layer without directly exposing it to surface irregularities.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The structure is segmented into distinct functional layers: the base layer provides mechanical support and stress relief, while the interlayer insulation layer provides surface planarization. This segmentation allows each layer to optimize its specific function without compromising the other.

Inventive Principle:

Principle #1Segmentation

2Ease of manufacture

If the tunnel barrier layer has poor flatness due to base layer surface irregularities, then the manufacturing process remains simple, but the magnetoresistive ratio decreases and breakdown risk increases

Engineering Contradiction:

Improvesimplicity of layer depositionVSAvoidmagnetoresistive ratio and durability

Core Design Contradiction:

Ease of manufactureVSReliability

Solution Approach 1:

The interlayer insulation layer serves as a protective intermediary that shields the tunnel barrier layer from stress and surface irregularities. This mediator ensures uniform voltage application across the tunnel barrier layer, suppresses in-plane currents, and prevents local breakdown, thereby maintaining high magnetoresistive ratio and durability.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The interlayer insulation layer is deposited beforehand to cushion and distribute mechanical stress from the base layer before the tunnel barrier layer is formed. This prior cushioning prevents stress-induced deformations in the tunnel barrier layer, ensuring its structural integrity and electrical performance.

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 improved flatness of the tunnel barrier layer results in a higher magnetoresistive ratio and increased durability by suppressing in-plane currents and reducing local voltage application, thereby enhancing the overall performance and reliability of the TMR element.

Implementation Method 1

a tunnel magnetoresistive effect (TMR) element having a configuration in which a reference layer as a magnetization fixed layer, a non-magnetic spacer layer, and a magnetization free layer are stacked in this order

Methodology Applied

Scientific EffectTunnel magnetoresistive effect: Magnetoresistance

Implementation Method 2

A technology called 'spin injection magnetization reversal' in which a spin transfer torque (STT) is applied to the magnetization free layer from electron spins by causing a spin-polarized current to flow through the magnetization free layer

Methodology Applied

Scientific EffectSpin transfer torque:

Data Source

PatentUS10522592B2Tunnel magnetoresistive effect element, magnetic memory, and built-in memory

Publication Date: 2019.12.31 TDK CORP

AI summary

A TMR element includes a base layer that is disposed on an upper surface of a via interconnect part, a magnetic tunnel junction that is disposed on a surface of the base layer, and an interlayer insulation layer that covers a side surface of each of the via interconnect part and the base layer. The base layer includes a stress relieving region. The magnetic tunnel junction includes a reference layer having a magnetization fixed direction, a magnetization free layer, and a tunnel barrier layer disposed between the reference layer and the magnetization free layer. The interlayer insulation layer includes an insulation material.