Interfacial nitridation for growth of perpendicularly magnetized Heusler films
A magnetoresistive random-access memory cell includes a substrate; a sub-monolayer nitride layer, outward of the substrate, having a sub-monolayer nitride layer thickness less than 10 Angstroms; and a templating layer, outward of the sub-monolayer nitride layer, and including a binary alloy having an alternating layer lattice structure. A Heusler layer is located outward of the templating layer. The Heusler layer includes a Heusler compound and exhibits perpendicular magnetic anisotropy (PMA). A tunnel barrier is outward of the Heusler layer, and a magnetic layer is outward of the tunnel barrier. In an alternative aspect, instead of the sub-monolayer nitride layer, a tantalum nitride layer with a thickness of ≤10 Angstroms+10% is employed.
1 . A magnetoresistive random-access memory cell, comprising:
a substrate;
a sub-monolayer non-magnetic nitride layer, outward of the substrate, and having a sub-monolayer non-magnetic nitride layer thickness less than 10 Angstroms;
a templating layer, outward of the sub-monolayer non-magnetic nitride layer, comprising a binary alloy having an alternating layer lattice structure;
a Heusler layer located outward of the templating layer, the Heusler layer comprising a Heusler compound and exhibiting perpendicular magnetic anisotropy (PMA);
a tunnel barrier outward of the Heusler layer; and
a magnetic layer outward of the tunnel barrier.
2 . The magnetoresistive random-access memory cell of claim 1 , wherein:
the Heusler layer comprises a storage layer; and
the magnetic layer comprises a reference layer.
3 . The magnetoresistive random-access memory cell of claim 2 , wherein the Heusler compound is selected from the group consisting of Mn 3 Ge, Mn 3 Sn, Mn 3 Sb, Mn 2 CoSn, Mn 2 FeSb, Mn 3 CoAl, Mn 2 CoGe, Mn 2 CoSi, Mn 2 CuSi, Co 2 CrAl, Co 2 CrSi, Co 2 MnSb, and Co 2 MnSi.
4 . The magnetoresistive random-access memory cell of claim 3 , wherein the Heusler layer has a thickness of less than 5 nm.
5 . The magnetoresistive random-access memory cell of claim 4 , wherein the tunnel barrier is selected from the group consisting of magnesium oxide and magnesium aluminum oxide.
6 . The magnetoresistive random-access memory cell of claim 5 , wherein the tunnel barrier comprises magnesium oxide.
7 . The magnetoresistive random-access memory cell of claim 5 , wherein the tunnel barrier comprises Mg 1-z Al 2+(2/3)z O 4 , wherein −0.5<z<0.5.
8 . The magnetoresistive random-access memory cell of claim 5 , wherein the binary alloy is represented by A 1-x E x , wherein A is a transition metal element and E is a main group element including at least one of aluminum and gallium, and x is in the range from 0.42 to 0.55.
9 . The magnetoresistive random-access memory cell of claim 2 , wherein the Heusler compound comprises Mn 3 Ge.
10 . The magnetoresistive random-access memory cell of claim 1 , wherein:
the Heusler layer comprises a reference layer; and
the magnetic layer comprises a storage layer.
11 . The magnetoresistive random-access memory cell of claim 10 , wherein the Heusler compound is selected from the group consisting of Mn 3 Ge, Mn 3 Sn, Mn 3 Sb, Mn 2 CoSn, Mn 2 FeSb, Mn 3 CoAl, Mn 2 CoGe, Mn 2 CoSi, Mn 2 CuSi, Co 2 CrAl, Co 2 CrSi, Co 2 MnSb, and Co 2 MnSi.
12 . The magnetoresistive random-access memory cell of claim 11 , wherein the Heusler layer has a thickness of less than 5 nm.
13 . The magnetoresistive random-access memory cell of claim 12 , wherein the tunnel barrier is selected from the group consisting of magnesium oxide and magnesium aluminum oxide.
14 . The magnetoresistive random-access memory cell of claim 13 , wherein the tunnel barrier comprises magnesium oxide.
15 . The magnetoresistive random-access memory cell of claim 13 , wherein the tunnel barrier comprises Mg 1-z Al 2+(2/3)z O 4 , wherein −0.5<z<0.5.
16 . The magnetoresistive random-access memory cell of claim 13 , wherein the binary alloy is represented by A 1-x E x , wherein A is a transition metal element and E is a main group element including at least one of aluminum and gallium, and x is in the range from 0.42 to 0.55.
17 . The magnetoresistive random-access memory cell of claim 10 , wherein the Heusler compound comprises Mn 3 Ge.
18 . The magnetoresistive random-access memory cell of claim 1 , wherein the alternating layer lattice structure of the templating layer comprises a cesium chloride structure.
19 . The magnetoresistive random-access memory cell of claim 1 , wherein the sub-monolayer non-magnetic nitride layer has over-stoichiometric nitrogen composition.
20 . A magnetoresistive random-access memory cell, comprising:
a substrate;
a non-magnetic tantalum nitride layer, outward of the substrate, and having a non-magnetic tantalum nitride layer thickness ranging from a sub-monolayer to a maximum≤10 Angstroms+/−10%;
a templating layer, outward of the non-magnetic tantalum nitride layer, comprising a binary alloy having an alternating layer lattice structure;
a Heusler layer located outward of the templating layer, the Heusler layer comprising a Heusler compound and exhibiting perpendicular magnetic anisotropy (PMA);
a tunnel barrier outward of the Heusler layer; and
a magnetic layer outward of the tunnel barrier.
21 . The magnetoresistive random-access memory cell of claim 20 , wherein:
the Heusler layer comprises a reference layer;
the magnetic layer comprises a storage layer; and
the Heusler compound is selected from the group consisting of Mn 3 Ge, Mn 3 Sn, Mn 3 Sb, Mn 2 CoSn, Mn 2 FeSb, Mn 3 CoAl, Mn 2 CoGe, Mn 2 CoSi, Mn 2 CuSi, Co 2 CrAl, Co 2 CrSi, Co 2 MnSb, and Co 2 MnSi.
22 . A magnetoresistive random-access memory array, comprising:
a plurality of bit lines and a plurality of complementary bit lines forming a plurality of bit line-complementary bit line pairs;
a plurality of word lines intersecting the plurality of bit line pairs at a plurality of cell locations; and
a plurality of magnetoresistive random-access memory cells located at each of the plurality of cell locations, each of the magnetoresistive random-access memory cells being electrically connected to a corresponding bit line and selectively interconnected to a corresponding one of the complementary bit lines under control of a corresponding one of the word lines, each of the plurality of magnetoresistive random-access memory cells comprising:
a substrate;
a sub-monolayer non-magnetic nitride layer, outward of the substrate, and having a sub-monolayer non-magnetic nitride layer thickness less than 10 Angstroms;
a templating layer, outward of the sub-monolayer non-magnetic nitride layer, comprising a binary alloy having an alternating layer lattice structure;
a Heusler layer located outward of the templating layer, the Heusler layer comprising a Heusler compound and exhibiting perpendicular magnetic anisotropy (PMA);
a tunnel barrier outward of the Heusler layer; and
a magnetic layer outward of the tunnel barrier.
23 . The magnetoresistive random-access memory array of claim 22 , wherein:
the Heusler layer comprises a storage layer;
the magnetic layer comprises a reference layer,
the sub-monolayer non-magnetic nitride layer is a sub-monolayer non-magnetic tantalum nitride layer; and
the Heusler compound is selected from the group consisting of Mn 3 Ge, Mn 3 Sn, Mn 3 Sb, Mn 2 CoSn, Mn 2 FeSb, Mn 3 CoAl, Mn 2 CoGe, Mn 2 CoSi, Mn 2 CuSi, Co 2 CrAl, Co 2 CrSi, Co 2 MnSb, and Co 2 MnSi.
24 . A method of forming a magnetoresistive random-access memory cell, comprising:
providing a substrate;
forming a sub-monolayer non-magnetic nitride layer, outward of the substrate, and having a sub-monolayer non-magnetic nitride layer thickness less than 10 Angstroms;
providing a templating layer, outward of the sub-monolayer non-magnetic nitride layer, and comprising a binary alloy having an alternating layer lattice structure;
epitaxially growing a Heusler layer on the templating layer, the Heusler layer comprising a Heusler material;
forming a tunnel barrier outward of the Heusler layer; and
forming a magnetic layer outward of the tunnel barrier.
25 . A hardware description language (HDL) design structure encoded on a machine-readable data storage medium, the HDL design structure comprising elements that when processed in a computer-aided design system generates a machine-executable representation of a magnetoresistive random-access memory cell, wherein the (HDL design structure) comprises:
a substrate;
a sub-monolayer non-magnetic nitride layer, outward of the substrate, and having a sub-monolayer non-magnetic nitride layer thickness less than 10 Angstroms;
a templating layer, outward of the sub-monolayer non-magnetic nitride layer, comprising a binary alloy having an alternating layer lattice structure;
a Heusler layer located outward of the templating layer, the Heusler layer comprising a Heusler compound and exhibiting perpendicular magnetic anisotropy (PMA);
a tunnel barrier outward of the Heusler layer; and
a magnetic layer outward of the tunnel barrier.