VCMA Memory Device with Metal Dust Layers

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Solution Overview

Problem

Magnetic tunnel junction devices face challenges in enhancing voltage-controlled magnetic anisotropy (VCMA) to improve energy efficiency and thermal stability for magnetization switching, requiring increased VCMA coefficients at lower external voltages.

Innovation Solution

Incorporating nonmagnetic metal dust layers with opposite VCMA coefficients on either side of the free layer and employing a two-dimensional metal compound layer with in-plane covalent bonding and out-of-plane van der Waals bonding within the magnetic tunnel junction to enhance the overall VCMA coefficient.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Use of energy by moving object

If conventional magnetic tunnel junction structures are used, then device simplicity is maintained, but voltage-controlled magnetic anisotropy coefficient is insufficient for energy-efficient operation

Engineering Contradiction:

Improveenergy efficiencyVSAvoiddevice complexity

Core Design Contradiction:

Use of energy by moving objectVSDevice complexity

Solution Approach 1:

The patent employs composite material structures including nonmagnetic metal dust layers (such as Ir, Pt, W, Ta, Hf, Ru, or Rh) integrated within the magnetic tunnel junction. These dust layers form composite interfaces with magnetic layers to generate enhanced voltage-controlled magnetic anisotropy coefficients, enabling energy-efficient magnetization switching while maintaining practical device complexity through standardized thin-film fabrication processes

Inventive Principle:

Principle #40Composite materials

Solution Approach 2:

The invention applies local quality enhancement by positioning nonmagnetic metal dust layers at specific interfaces within the magnetic tunnel junction where they can locally generate strong VCMA effects. The dust layers are strategically placed between magnetic layers to create localized regions of enhanced magnetic anisotropy control, allowing efficient switching at the critical interface regions without requiring global structural changes

Inventive Principle:

Principle #3Local quality

2Reliability

If higher external voltages are applied to increase VCMA coefficient, then magnetization switching effectiveness is improved, but energy consumption increases

Engineering Contradiction:

Improvemagnetization switching effectivenessVSAvoidenergy consumption

Core Design Contradiction:

ReliabilityVSLoss of energy

Solution Approach 1:

The patent fundamentally changes the material parameter VCMA coefficient by incorporating nonmagnetic metal dust layers with specific properties (such as Ir, Pt, W, Ta, Hf, Ru, or Rh). This material parameter change enables achieving reliable magnetization switching at lower external voltages, thereby reducing energy consumption while maintaining switching effectiveness through the enhanced intrinsic VCMA response of the dust layer interfaces

Inventive Principle:

Principle #35Parameter changes

3Reliability

If VCMA coefficient is increased for better thermal stability, then magnetization switching reliability is improved, but device structure becomes more complex

Engineering Contradiction:

Improvemagnetization switching reliabilityVSAvoiddevice structure

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent achieves improved thermal stability and switching reliability through composite material interfaces formed by nonmagnetic metal dust layers. These dust layer interfaces (such as Ir/CoFeB, Pt/CoFeB, W/CoFeB, Ta/CoFeB, Hf/CoFeB, Ru/CoFeB, or Rh/CoFeB) provide enhanced VCMA coefficients that ensure reliable magnetization switching while maintaining compatibility with standard thin-film deposition techniques, avoiding excessive structural complexity

Inventive Principle:

Principle #40Composite materials

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 significantly increases the VCMA coefficient, enabling efficient magnetization switching at lower voltages, improving energy efficiency and thermal stability, and enhancing the endurance of magnetoelectric random access memory (MeRAM) devices.

Implementation Method 1

Voltage-controlled magnetic anisotropy (VCMA) refers to magnetic anisotropy that increase or decreases with application of an electric field across a magnetic tunnel junction

Methodology Applied

Scientific EffectVoltage-controlled magnetic anisotropy (VCMA):

Implementation Method 2

a two-dimensional metal compound layer including a two-dimensional compound of a nonmagnetic metallic element and a nonmetallic element having in-plane covalent bonding and out-of-plane van der Waals bonding

Methodology Applied

Scientific EffectVan der Waals bonding: Van der Waals Force

Data Source

PatentUS11871679B2Voltage-controlled magnetic anisotropy memory device including an anisotropy-enhancing dust layer and methods for forming the same

Publication Date: 2024.01.09 SANDISK TECHNOLOGIES LLC

AI summary

A magnetoelectric memory device includes a magnetic tunnel junction located between a first electrode and a second electrode. The magnetic tunnel junction includes a reference layer, a nonmagnetic tunnel barrier layer, a free layer, and a dielectric capping layer. At least one layer that provides voltage-controlled magnetic anisotropy is provided within the magnetic tunnel junction, which may include a pair of nonmagnetic metal dust layers located on, or within, the free layer, or a two-dimensional metal compound layer including a compound of a nonmagnetic metallic element and a nonmetallic element.