Magnetic Memory Underlayer for Perpendicular Anisotropy

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Solution Overview

Problem

Magnetic memories with perpendicular magnetic anisotropy face challenges in achieving strong perpendicular magnetic anisotropy and maintaining magnetic coupling between the data recording layer and the magnetization fixed layer, particularly when using a Co/Ni film stack, which is difficult to form with high fcc (111) orientation.

Innovation Solution

A magnetic memory structure is developed with a data recording layer having perpendicular magnetic anisotropy, incorporating a first magnetic underlayer of NiFe doped with non-magnetic elements like Zr, Ta, W, Hf, or V, and a non-magnetic underlayer of Pt, Au, Pd, or Ir, along with a second magnetic underlayer of Co or Fe, to enhance both the perpendicular magnetic anisotropy and magnetic coupling.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If a Co/Ni film stack is used as a data recording layer, then perpendicular magnetic anisotropy can be achieved, but it is difficult to form with high fcc (111) orientation

Engineering Contradiction:

Improvefcc (111) orientationVSAvoidfilm formation difficulty

Core Design Contradiction:

Manufacturing precisionVSEase of manufacture

Solution Approach 1:

An underlayer comprising a first magnetic underlayer and a non-magnetic underlayer is introduced as an intermediary between the substrate and the Co/Ni data recording layer. The non-magnetic underlayer (e.g., Pt, Au, Pd, or Ir) serves as a mediator that facilitates the formation of high fcc (111) orientation in the Co/Ni film stack, enabling perpendicular magnetic anisotropy without directly participating in the magnetic coupling.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The underlayer is constructed as a composite structure combining a first magnetic underlayer (e.g., NiFe doped with non-magnetic elements like Zr, Ta, W, Hf, or V) and a non-magnetic underlayer. This composite material structure synergistically provides both the magnetic coupling function and the crystallographic template for achieving high fcc (111) orientation in the data recording layer.

Inventive Principle:

Principle #40Composite materials

2Manufacturing precision

If the underlayer is designed to enhance perpendicular magnetic anisotropy, then magnetic coupling between data recording layer and magnetization fixed layer may be weakened

Engineering Contradiction:

Improveperpendicular magnetic anisotropyVSAvoidmagnetic coupling

Core Design Contradiction:

Manufacturing precisionVSReliability

Solution Approach 1:

The underlayer is segmented into two distinct functional layers: a first magnetic underlayer that provides magnetic coupling between the data recording layer and the magnetization fixed layer, and a non-magnetic underlayer that enhances perpendicular magnetic anisotropy by facilitating fcc (111) orientation. This segmentation allows each layer to independently fulfill its specific function without compromising the other.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Different regions of the underlayer structure are assigned different magnetic properties: the first magnetic underlayer maintains ferromagnetic characteristics for coupling, while the non-magnetic underlayer is designed with non-magnetic properties to optimize crystallographic orientation. This local differentiation of material properties enables simultaneous achievement of magnetic coupling and perpendicular anisotropy.

Inventive Principle:

Principle #3Local quality

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 structure achieves strong perpendicular magnetic anisotropy and improved magnetic coupling, reducing the write current required for domain wall motion and enhancing the magnetic memory's performance, particularly in achieving fcc (111) orientation for the Co/Ni film stack.

Implementation Method 1

a first magnetic underlayer with perpendicular magnetic anisotropy

Methodology Applied

Scientific EffectPerpendicular magnetic anisotropy: Anisotropy

Implementation Method 2

enhance both the perpendicular magnetic anisotropy and magnetic coupling

Methodology Applied

Scientific EffectMagnetic coupling: Magnetism

Implementation Method 3

when a current is flown in the direction through a domain wall, the domain wall is moved in the direction of the conduction electrons

Methodology Applied

Scientific EffectCurrent driven domain wall motion: Lorentz Force

Data Source

PatentUS8830735B2Magnetic memory including memory cells incorporating data recording layer with perpendicular magnetic anisotropy film

Publication Date: 2014.09.09 RENESAS ELECTRONICS CORP

AI summary

A magnetic memory includes: a magnetization fixed layer having perpendicular magnetic anisotropy, a magnetization direction of the magnetization fixed layer being fixed; an interlayer dielectric; an underlayer formed on upper faces of the magnetization fixed layer and the interlayer dielectric; and a data recording layer formed on an upper face of the underlayer and having perpendicular magnetic anisotropy. The underlayer includes: a first magnetic underlayer; and a non-magnetic underlayer formed on the first magnetic underlayer. The first magnetic underlayer is formed with such a thickness that the first magnetic underlayer does not exhibit in-plane magnetic anisotropy in a portion of the first magnetic underlayer formed on the interlayer dielectric.