Self-Pinned Magnetic Junction for High-Density MRAM

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Solution Overview

Problem

Conventional dual magnetic tunneling junctions (MTJs) face challenges in higher density memory fabrication due to reduced magnetoresistance and increased complexity, making it difficult to achieve high-density magnetic random access memories (MRAMs) with efficient switching and stability.

Innovation Solution

A magnetic junction design featuring self-pinned, nonmagnetic layer-free pinned layers and a configuration allowing the free layer to switch between multiple stable states using write currents, with antiferromagnetic coupling and reduced thickness for improved tunneling magnetoresistance and reduced spin transfer switching current density.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If conventional dual magnetic tunneling junctions are used in higher density memory fabrication, then the structure provides magnetic storage functionality, but the magnetoresistance is reduced and device complexity increases

Engineering Contradiction:

ImprovemagnetoresistanceVSAvoiddevice complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent extracts and removes the nonmagnetic spacer layers from the pinned layer structure, creating a nonmagnetic layer-free pinned layer. This extraction eliminates the source of interface roughness and reduces device complexity while maintaining the magnetic storage functionality through the self-pinned configuration of the remaining magnetic layers

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The patent merges the functions of multiple layers into a simplified pinned layer structure where the magnetic layers are directly coupled without intermediate nonmagnetic spacers. This merging reduces the number of interfaces and layers, thereby reducing device complexity and improving magnetoresistance by eliminating interface roughness

Inventive Principle:

Principle #5Merging (Combining)

2Productivity

If conventional dual magnetic tunneling junctions are used, then magnetic storage functionality is provided, but switching current density increases

Engineering Contradiction:

Improveswitching efficiencyVSAvoidswitching current density

Core Design Contradiction:

ProductivityVSUse of energy by moving object

Solution Approach 1:

The patent implements a self-pinned configuration where the magnetic layers within the pinned layer structure provide mutual pinning through direct magnetic coupling without requiring external nonmagnetic spacer layers. This self-service mechanism reduces the energy required for switching by optimizing the magnetic field interactions and reducing the switching current density

Inventive Principle:

Principle #25Self-service

3Reliability

If conventional dual magnetic tunneling junctions are used, then the structure provides adequate magnetic coupling, but layer thickness increases

Engineering Contradiction:

Improvemagnetic coupling stabilityVSAvoidlayer thickness

Core Design Contradiction:

ReliabilityVSLength of stationary object

Solution Approach 1:

The patent extracts the nonmagnetic spacer layers from the pinned layer structure, removing unnecessary thickness while maintaining magnetic coupling stability through the direct coupling of magnetic layers. This extraction reduces the overall layer thickness without compromising the magnetic coupling between the pinned layer and free layer

Inventive Principle:

Principle #2Taking out (Extraction)

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 proposed magnetic junction design enhances tunneling magnetoresistance, reduces spin transfer switching current density, and facilitates thinner structures, enabling more efficient and scalable high-density MRAM fabrication with improved control over layer roughness and annealing processes.

Implementation Method 1

STT-RAM utilizes magnetic junctions written at least in part by a current driven through the magnetic junction

Methodology Applied

Scientific EffectSpin transfer torque:

Implementation Method 2

enhances tunneling magnetoresistance

Methodology Applied

Scientific EffectTunneling magnetoresistance: Magnetoresistance

Data Source

PatentUS8422285B2Method and system for providing dual magnetic tunneling junctions usable in spin transfer torque magnetic memories

Publication Date: 2013.04.16 SAMSUNG SEMICONDUCTOR INC

AI summary

A method and system for providing a magnetic junction usable in a magnetic memory are described. The magnetic junction includes first and second pinned layers, first and second nonmagnetic spacer layers, and a free layer. The pinned layers are nonmagnetic layer-free and self-pinned. In some aspects, the magnetic junction is configured to allow the free and second pinned layers to be switched between stable magnetic states when write currents are passed therethrough. The magnetic junction has greater than two stable states. In other aspects, the magnetic junction includes at least third and fourth spacer layers, a second free layer therebetween, and a third pinned layer having a pinned layer magnetic moment, being nonmagnetic layer-free, and being coupled to the second pinned layer. The magnetic junction is configured to allow the free layers to be switched between stable magnetic states when write currents are passed therethrough.