Engineered Secondary Barrier Layer for STT-MRAM Write Current Reduction

Solution Overview

Problem

Conventional dual magnetic tunneling junctions in spin transfer torque random access memories (STT-MRAMs) face challenges in achieving low switching current and high signal, which limits their performance and efficiency.

Innovation Solution

The introduction of an engineered secondary barrier layer with a reduced thickness and regions of lower resistance, such as pinholes or doped regions, between the free layer and the second reference layer, enhances the tunneling magnetoresistance and allows for improved write and read characteristics by reducing the resistance area product and preserving spin torque.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Use of energy by moving object

If the secondary tunneling barrier layer is made thinner to reduce resistance area product, then write current is reduced, but the barrier layer loses its tunneling capability

Engineering Contradiction:

Improvewrite currentVSAvoidtunneling capability

Core Design Contradiction:

Use of energy by moving objectVSReliability

Solution Approach 1:

The patent applies local quality by creating pinhole regions with different properties than the bulk barrier layer. The pinholes provide low-resistance pathways for spin-polarized current while the surrounding barrier material maintains the tunneling effect. This spatial differentiation of properties allows simultaneous optimization of write current and tunneling capability.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The engineered secondary barrier layer incorporates a porous structure with pinhole defects that allow controlled current transport. The porous morphology enables the barrier to function as both a tunneling barrier and a spin transport channel, resolving the contradiction between thinning for lower resistance and maintaining barrier integrity.

Inventive Principle:

Principle #31Porous materials

2Use of energy by moving object

If dual state magnetization is used to reduce switching current, then write current is reduced, but tunneling magnetoresistance is reduced

Engineering Contradiction:

Improveswitching currentVSAvoidtunneling magnetoresistance

Core Design Contradiction:

Use of energy by moving objectVSReliability

Solution Approach 1:

The patent applies local quality by creating pinhole regions with different properties than the bulk barrier layer. The pinholes provide low-resistance pathways for spin-polarized current while the surrounding barrier material maintains the tunneling effect. This spatial differentiation of properties allows simultaneous optimization of write current and tunneling capability.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The engineered secondary barrier layer incorporates a porous structure with pinhole defects that allow controlled current transport. The porous morphology enables the barrier to function as both a tunneling barrier and a spin transport channel, resolving the contradiction between thinning for lower resistance and maintaining barrier integrity.

Inventive Principle:

Principle #31Porous 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

This configuration results in improved read and write performance, enabling lower write currents and increased tunneling magnetoresistance, potentially enhancing the overall performance of STT-MRAMs by up to 150%.

Implementation Method 1

A spin polarized current driven through the magnetic junction exerts a spin torque on the magnetic moments in the magnetic junction. As a result, layer(s) having magnetic moments that are responsive to the spin torque may be switched to a desired state.

Methodology Applied

Scientific EffectSpin transfer torque:

Implementation Method 2

The introduction of an engineered secondary barrier layer with a reduced thickness and regions of lower resistance, such as pinholes or doped regions, between the free layer and the second reference layer, enhances the tunneling magnetoresistance and allows for improved write and read characteristics by reducing the resistance area product and preserving spin torque.

Methodology Applied

Scientific EffectTunneling magnetoresistance: Magnetoresistance

Data Source

PatentUS20190273201A1Method and system for engineering the secondary barrier layer in dual magnetic junctions

Publication Date: 2019.09.05 SAMSUNG ELECTRONICS CO LTD

AI summary

A magnetic junction, a memory using the magnetic junction and method for providing the magnetic junction are described. The magnetic junction includes first and second reference layers, a main barrier layer having a first thickness, a free layer, an engineered secondary barrier layer and a second reference layer. The free layer is switchable between stable magnetic states when a write current is passed through the magnetic junction. The main barrier layer is between the first reference layer and the free layer. The secondary barrier layer is between the free layer and the second reference layer. The engineered secondary barrier layer has a resistance, a second thickness less than the first thickness and a plurality of regions having a reduced resistance less than the resistance. The free and reference layers each has a perpendicular magnetic anisotropy energy and an out-of-plane demagnetization energy less than the perpendicular magnetic anisotropy energy.