Magnetoresistance effect element

Patent metadata

Field	Value
Publication number	US-10629231-B2
Application number	US-201916250557-A
Country	US
Kind code	B2
Filing date	Jan 17, 2019
Priority date	Mar 31, 2015
Publication date	Apr 21, 2020
Grant date	Apr 21, 2020

Abstract

A magnetoresistance effect element has a first ferromagnetic metal layer, a second ferromagnetic metal layer, and a tunnel barrier layer that is sandwiched between the first and second ferromagnetic metal layers, the tunnel barrier layer is expressed by a chemical formula of AB 2 O x , and has a spinel structure in which cations are arranged in a disordered manner, A represents a divalent cation that is either Mg or Zn, and B represents a trivalent cation that includes a plurality of elements selected from the group consisting of Al, Ga, and In.

First claim

The invention claimed is:

1. A magnetoresistance effect element comprising:
a first ferromagnetic metal layer;
a second ferromagnetic metal layer; and
a tunnel barrier layer that is sandwiched between the first and second ferromagnetic metal layers,
wherein the tunnel barrier layer has a spinel structure, wherein
the tunnel barrier layer comprises: at least one lattice-matched portion that is lattice-matched with both of the first ferromagnetic metal layer and the second ferromagnetic metal layer; and at least one lattice-mismatched portion that is not lattice-matched with at least one of the first ferromagnetic metal layer and the second ferromagnetic metal layer, and
when viewed as an inverse Fourier transform image in a stacking direction of a cross-sectional crystal lattice image of the interface between the tunnel barrier layer and the first and/or the second ferromagnetic metal layer, a lattice-matched portion is made up of a plurality of sequential, continuously-connected lattice lines, and a lattice-mismatched portion is made up of a plurality of sequential, non-continuously-connected lattice lines and/or no lattice lines.

2. The magnetoresistance effect element according to claim 1 ,
wherein a volume ratio of the lattice-matched portion with respect to a volume of the entire tunnel barrier layer is 65% to 95%.

3. The magnetoresistance effect element according to claim 1 ,
wherein the number of constituent elements in a unit cell of the divalent cation is smaller than half that of the trivalent cation.

4. The magnetoresistance effect element according to claim 1 ,
wherein a magnetoresistance ratio is 100% or greater under application of a bias voltage of 1 V or greater at a room temperature.

5. The magnetoresistance effect element according to claim 1 ,
wherein the first ferromagnetic metal layer has larger coercivity than the second ferromagnetic metal layer.

6. The magnetoresistance effect element according to claim 1 ,
wherein at least one of the first ferromagnetic metal layer and the second ferromagnetic metal layer has magnetic anisotropy perpendicular to a stacking direction.

7. The magnetoresistance effect element according to claim 1 ,
wherein at least one of the first ferromagnetic metal layer and the second ferromagnetic metal layer is Co 2 Mn 1-a Fe a Al b SiI b (0≤a≤1, 0≤b≤1).

8. The magnetoresistance effect element according to claim 1 ,
wherein the tunnel barrier layer is expressed by a chemical formula of AB 2 O x (0<x≤4),
A represents a divalent cation that is either Mg or Zn, and
B represents a trivalent cation that is either Al, Ga or In.

9. The magnetoresistance effect element according to claim 1 ,
wherein cations are arranged in a disordered manner in the spinel structure.

10. A method of manufacturing a magnetoresistance effect element comprising the steps of:
forming an under layer on a substrate;
forming a first ferromagnetic metal layer on the under layer;
forming a tunnel barrier layer on the first ferromagnetic metal layer;
forming a second ferromagnetic metal layer on the tunnel barrier layer; and
forming a cap layer on the second ferromagnetic metal layer, wherein
the step of forming a tunnel barrier layer comprises the steps of:
depositing a metal thin film on the first ferromagnetic metal layer;
oxidizing the deposited metal thin film by plasma oxidation or natural oxidation by introducing oxide; and
heat treating the oxidized metal thin film, and

the step of oxidizing is performed after cooling the substrate to −70° C. to −30° C., and wherein
the tunnel barrier layer comprises: at least one lattice-matched portion that is lattice-matched with both of the first ferromagnetic metal layer and the second ferromagnetic metal layer; and at least one lattice-mismatched portion that is not lattice-matched with at least one of the first ferromagnetic metal layer and the second ferromagnetic metal layer, and
when viewed as an inverse Fourier transform image in a stacking direction of a cross-sectional crystal lattice image of the interface between the tunnel barrier layer and the first and/or the second ferromagnetic metal layer, a lattice-matched portion is made up of a plurality of sequential, continuously-connected lattice lines, and a lattice-mismatched portion is made up of a plurality of sequential, non-continuously-connected lattice lines and/or no lattice lines.

Assignees

• Tdk Corp

Inventors

• Sasaki Tomoyuki

Classifications

• G11B5/39

  using magneto-resistive devices {or effects} · CPC title

• H01F10/1936

  Half-metallic, e.g. epitaxial CrO2 or NiMnSb films · CPC title

• G11B2005/3996

  large or giant magnetoresistive effects [GMR], e.g. as generated in spin-valve [SV] devices · CPC title

• G11B5/3909 Primary

  Arrangements using a magnetic tunnel junction · CPC title

• H01F1/405

  of IV type, e.g. Ge1-xMnx · CPC title