Magnetic Tunnel Junction Free Layer Segmentation for Low Switching Current

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Solution Overview

Problem

Magnetic memory devices face challenges in reducing switching current while maintaining thermal stability, which is crucial for high-speed and low-power operations.

Innovation Solution

The magnetic memory device incorporates a magnetic tunnel junction pattern with a free pattern comprising sub-free patterns of cobalt-iron-boron (CoFeB), nickel-cobalt-iron-boron (NiCoFeB), and nickel-iron-boron (NiFeB) layers, strategically positioned and processed to minimize switching current while maintaining thermal stability.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Speed

If a magnetic tunnel junction is used for high-speed operation, then switching speed is improved, but switching current becomes excessively high

Engineering Contradiction:

Improveswitching speedVSAvoidswitching current

Core Design Contradiction:

SpeedVSUse of energy by moving object

Solution Approach 1:

The free layer is segmented into multiple sub-layers (first sub-free layer, second sub-free layer, third sub-free layer) with different material compositions. Each sub-layer contributes differently to the magnetic properties, allowing optimization of both switching speed and switching current by controlling the magnetization switching behavior of individual sub-layers

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Different sub-layers are assigned different local qualities through varying material compositions (CoFeB, NiCoFeB, NiFeB) and thicknesses. This creates localized magnetic properties that can be independently optimized, with each sub-layer having specific saturation magnetization and anisotropy characteristics that collectively achieve low switching current while maintaining high-speed operation

Inventive Principle:

Principle #3Local quality

2Ease of manufacture

If the free layer uses simple material composition, then manufacturing is easier, but thermal stability deteriorates

Engineering Contradiction:

Improvemanufacturing simplicityVSAvoidthermal stability

Core Design Contradiction:

Ease of manufactureVSStability of the object's composition

Solution Approach 1:

The free layer is constructed as a composite structure with three different magnetic alloy sub-layers (CoFeB, NiCoFeB, NiFeB), each providing specific magnetic properties. This composite approach enables fine-tuning of thermal stability through material selection and thickness control while maintaining compatibility with existing manufacturing processes

Inventive Principle:

Principle #40Composite materials

Solution Approach 2:

Thermal stability is optimized by adjusting parameters such as the thickness of each sub-layer and the nickel content in NiCoFeB and NiFeB layers. By changing these parameters within specific ranges, the product of saturation magnetization and thickness (Ms×t) is controlled to achieve desired thermal stability without requiring fundamentally new manufacturing techniques

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

This configuration effectively reduces switching current while ensuring thermal stability, enhancing the performance of magnetic memory devices by optimizing the magnetic tunnel junction pattern.

Implementation Method 1

The magnetic tunnel junction may have a high resistance when the magnetization directions of the two magnetic layers are anti-parallel to each other. On the contrary, the magnetic tunnel junction may have a low resistance when the magnetization directions of the two magnetic layers are parallel to each other. The magnetic memory device may write/sense data by using a difference between the resistances of the magnetic tunnel junction.

Methodology Applied

Scientific EffectSpin transfer torque:

Implementation Method 2

The magnetic tunnel junction may include two magnetic layers and an insulating layer disposed between the two magnetic layers, and a resistance of the magnetic tunnel junction may be changed according to magnetization directions of the two magnetic layers.

Methodology Applied

Scientific EffectMagnetoresistance: Magnetoresistance

Data Source

PatentUS10431627B2Magnetic memory devices and methods for manufacturing the same

Publication Date: 2019.10.01 SAMSUNG ELECTRONICS CO LTD

AI summary

A magnetic memory device is provided including a magnetic tunnel junction pattern having a free pattern, a reference pattern, and a tunnel barrier pattern between the free pattern and the reference pattern. The free pattern includes a first sub-free pattern, a second sub-free pattern, and a third sub-free pattern. The first sub-free pattern is between the tunnel barrier pattern and the third sub-free pattern, and the second sub-free pattern is between the first sub-free pattern and the third sub-free pattern. The second sub-free pattern includes nickel-cobalt-iron-boron (NiCoFeB), and the third sub-free pattern includes nickel-iron-boron (NiFeB). Related methods of fabrication are also provided.