Magnetoresistive Stack iPMA Layer Switching

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Magnetoresistive stacks face challenges in achieving reliable high-speed writing performance due to damping forces and switching inefficiencies, particularly in short pulse operations, which require high amplitude write currents and result in poor endurance.

Innovation Solution

Incorporating interfacial perpendicular magnetic anisotropy inducing layers (iPMA layers) and low saturation magnetization layers in the free region of the magnetoresistive stack to increase anisotropy field strength while maintaining energy barrier and reducing saturation magnetization, allowing for reliable switching with low amplitude write currents.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Speed

If conventional magnetoresistive stacks are used for high-speed writing operations, then switching speed is improved, but write error rate increases and endurance deteriorates due to damping forces and switching inefficiencies

Engineering Contradiction:

Improveswitching speedVSAvoidwrite error rate

Core Design Contradiction:

SpeedVSReliability

Solution Approach 1:

The patent changes the magnetic anisotropy parameter from in-plane to perpendicular magnetic anisotropy by introducing iPMA layers. This parameter change enables the free region to achieve stable magnetization states with lower damping forces, allowing high-speed switching while maintaining low write error rates and improved endurance

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent employs composite material structures including iPMA layers (comprising metal, metal oxide, or both) combined with ferromagnetic materials in the free region. This composite structure creates interfacial perpendicular magnetic anisotropy that reduces damping forces and enables reliable high-speed switching operations with reduced write error rates

Inventive Principle:

Principle #40Composite materials

2Reliability

If high amplitude write currents are applied to achieve reliable switching in short pulse operations, then switching reliability is improved, but device endurance deteriorates

Engineering Contradiction:

Improveswitching reliabilityVSAvoiddevice endurance

Core Design Contradiction:

ReliabilityVSDuration of action of stationary object

Solution Approach 1:

The patent changes the magnetization switching mechanism by introducing perpendicular magnetic anisotropy through iPMA layers. This enables the system to achieve reliable switching with low amplitude write currents by utilizing spin transfer torque more efficiently, thereby improving device endurance while maintaining switching reliability in short pulse operations

Inventive Principle:

Principle #35Parameter changes

3Stability of the object's composition

If damping forces are present in the free region, then magnetization stability is improved, but switching efficiency deteriorates requiring higher write currents

Engineering Contradiction:

Improvemagnetization stabilityVSAvoidswitching efficiency

Core Design Contradiction:

Stability of the object's compositionVSProductivity

Solution Approach 1:

The patent changes the magnetic anisotropy orientation from in-plane to perpendicular by introducing iPMA layers. This parameter change fundamentally alters the magnetization dynamics, enabling stable magnetization states to be achieved with lower damping forces while maintaining high switching efficiency through spin transfer torque mechanisms

Inventive Principle:

Principle #35Parameter changes

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 improves the reliability and endurance of magnetoresistive devices by reducing write error rates and switching fluctuations, enabling efficient data retention and low amplitude, short pulse switching operations.

Implementation Method 1

Methodology Applied

Scientific EffectInterfacial perpendicular magnetic anisotropy: Anisotropy

Implementation Method 2

The direction of the magnetization vectors of the free region may be switched and/or programmed (for example, through spin transfer torque (STT)) by application of a write signal (e.g., one or more current pulses) adjacent to, or through, the magnetoresistive memory stack

Methodology Applied

Scientific EffectSpin transfer torque:

Implementation Method 3

The MTJ has different electrical resistances in the first and second magnetic states. For example, a resistance of the second magnetic state may be relatively higher than a resistance of the first magnetic state

Methodology Applied

Scientific EffectMagnetoresistance: Magnetoresistance

Data Source

PatentUS20230263071A1Magnetoresistive devices and methods therefor

Publication Date: 2023.08.17 EVERSPIN TECHNOLOGIES INC

AI summary

A magnetoresistive stack may include a first electrically conductive material, a fixed region having a fixed magnetic state, a free region configured to have a first magnetic state and a second magnetic state, a dielectric layer disposed between the fixed region and the free region, a spacer region, and a cap layer disposed between the spacer region and the free region. The free region may include a layer of ferromagnetic material, an insertion layer, an iPMA layer, and/or a low saturation magnetization layer.