Porous Non-Conductive Current Confinement Layer for MRAM

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Solution Overview

Problem

Current spin torque RAM technologies require high switching currents to change the magnetization orientation of magnetic elements, which limits chip capacity and increases power consumption.

Innovation Solution

Incorporating a porous non-conductive current confinement layer between the free layer and the pinned layer, or between the free layer and the non-magnetic spacer layer, to increase current density and reduce the switching current needed.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Use of energy by moving object

If a conventional magnetic element structure is used, then the device is simple to manufacture, but the switching current is too high

Engineering Contradiction:

Improveswitching currentVSAvoidlayer structure complexity

Core Design Contradiction:

Use of energy by moving objectVSDevice complexity

Solution Approach 1:

A porous non-conductive current confinement layer is introduced as an intermediary between the free layer and pinned layer. This layer confines the current path through the magnetic tunnel junction, increasing current density and reducing the switching current required. The porous structure with controlled porosity (30-70%) allows current confinement while maintaining spin tunneling efficiency.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The current confinement layer is designed with a porous structure rather than a solid continuous layer. The porous structure reduces the electrical conductivity of the layer while maintaining mechanical integrity and interface quality. The porosity can be controlled during deposition to optimize the balance between current confinement and spin tunneling efficiency.

Inventive Principle:

Principle #31Porous materials

2Reliability

If the current density is increased to reduce switching current, then the switching performance improves, but the power consumption increases

Engineering Contradiction:

Improveswitching performanceVSAvoidpower consumption

Core Design Contradiction:

ReliabilityVSLoss of energy

Solution Approach 1:

The porous non-conductive current confinement layer acts as a mediator that increases current density locally at the magnetic tunnel junction interface without requiring a proportional increase in total power. The layer confines the current path effectively, improving switching performance while the porous structure minimizes additional power consumption compared to a solid conductive confinement layer.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Manufacturing precision

If a non-conductive current confinement layer is added, then the current density control improves, but the manufacturing complexity increases

Engineering Contradiction:

Improvecurrent density controlVSAvoiddeposition process complexity

Core Design Contradiction:

Manufacturing precisionVSEase of manufacture

Solution Approach 1:

The porous structure is formed during the deposition process itself rather than requiring separate patterning steps. By controlling deposition parameters such as substrate temperature, deposition rate, and material selection, the porous structure forms in-situ, simplifying the manufacturing process while achieving precise current density control.

Inventive Principle:

Principle #31Porous materials

Solution Approach 2:

The porosity and electrical conductivity of the current confinement layer are controlled by adjusting deposition parameters. By changing parameters such as deposition temperature, rate, and material composition during deposition, the layer's properties are optimized for current confinement while maintaining ease of manufacture through a single deposition process.

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 implementation of a porous non-conductive current confinement layer decreases the switching current required to switch the magnetization orientation, thereby enhancing chip capacity and reducing power consumption while maintaining spin tunneling efficiency and TMR ratio.

Implementation Method 1

Spin torque transfer technology, also referred to as spin electronics, which is based on changing magnetic state of the system by momentum transfer from conduction electrons

Methodology Applied

Scientific EffectSpin torque transfer:

Implementation Method 2

The current direction is different for writing '1' or '0'. To write '1' (RH) the current flows from the pinned layer to the free layer, and reversed to flow from the free layer to the pinned layer to write '0' (RL)

Methodology Applied

Scientific EffectSpin tunneling:

Implementation Method 3

The magnetic element, in general, includes a ferromagnetic pinned layer (PL), and a ferromagnetic free layer (FL), each having a magnetization orientation. The magnetic element also includes a non-magnetic barrier layer. The respective magnetization orientations of the free layer and the pinned layer define the resistance of the overall magnetic element.

Methodology Applied

Scientific EffectTunneling magnetoresistance: Magnetoresistance

Data Source

PatentUS8456903B2Magnetic memory with porous non-conductive current confinement layer

Publication Date: 2013.06.04 SEAGATE TECH LLC

AI summary

A magnetic element having a ferromagnetic pinned layer, a ferromagnetic free layer, a non-magnetic spacer layer therebetween, and a porous non-electrically conducting current confinement layer between the free layer and the pinned layer. The current confinement layer forms an interface either between the free layer and the non-magnetic spacer layer or the pinned layer and the non-magnetic spacer layer.