Magnetic element with perpendicular magnetic anisotropy (PMA) and improved coercivity field (Hc)/switching current ratio

Patent metadata

Field	Value
Publication number	US-11264566-B2
Application number	US-201916448348-A
Country	US
Kind code	B2
Filing date	Jun 21, 2019
Priority date	Jun 21, 2019
Publication date	Mar 1, 2022
Grant date	Mar 1, 2022

Abstract

A perpendicular magnetic tunnel junction is disclosed wherein a metal insertion (MIS) layer is formed within a free layer (FL), a partially oxidized Hk enhancing layer is on the FL, and a nitride capping layer having a buffer layer/nitride layer (NL) is on the Hk enhancing layer to provide an improved coercivity (Hc)/switching current (Jc) ratio for spintronic applications. Magnetoresistive ratio is maintained above 100%, resistance×area (RA) product is below 5 ohm/μm 2 , and thermal stability to 400° C. is realized. The FL comprises two or more sub-layers, and the MIS layer may be formed within at least one sub-layer or between sub-layers. The buffer layer is used to prevent oxygen diffusion to the NL, and nitrogen diffusion from the NL to the FL. FL thickness is from 11 Angstroms to 25 Angstroms while MIS layer thickness is preferably from 0.5 Angstroms to 4 Angstroms.

First claim

We claim:

1. A perpendicular magnetic tunnel junction (p-MTJ) structure, comprising:
(a) a pinned layer (PL);
(b) a tunnel barrier layer with a first surface that adjoins the PL, and a second surface that contacts a free layer (FL) and forms a first interface with the FL;
(c) the FL that has a FL1/MIS/FL2 configuration wherein a metal insertion (MIS) layer is formed between a first FL sub-layer (FL1) and a second FL sub-layer (FL2), and wherein FL1 has perpendicular magnetic anisotropy (PMA) as a result of the first interface, and FL2 has PMA as a result of a second interface with a Hk enhancing layer;
(d) the Hk enhancing layer having a non-stoichiometric oxidation condition, and that adjoins the FL to form the second interface on a side of the FL that is opposite to the first interface; and
(e) a nitride capping layer (NCL), comprising:
(1) a nitride layer (NL) that is a metal nitride or metal oxynitride; and
(2) a buffer layer that is a single layer or multilayer that is one or more of Co, Fe, CoFe, and CoFeNi, or one or more of Mo, W, Ru, Nb, Ta, Cr, Pt, Cu, Au, Ag, Zn, V, Cd, Sn, Ir, Mn, and Rh that adjoins the NL and contacts the Hk enhancing layer on a side thereof that is opposite to the second interface, wherein the buffer layer prevents oxygen diffusion from the Hk enhancing layer to the NL, and blocks nitrogen diffusion from the NL to the FL.

2. The p-MTJ of claim 1 wherein the MIS layer is a continuous layer, a multilayer, a discontinuous layer, or is a plurality of metal particles, or metal clusters.

3. The p-MTJ of claim 1 wherein the MIS layer has a thickness from 0.5 Angstroms to 4 Angstroms.

4. The p-MTJ of claim 1 wherein the MIS layer is a single layer or multilayer of one or more of Nb, Mo, Ta, W, Re, Ti, V, Cr, Zr, Hf, Ru, Rh, Os, Ir, Cu, Zn, Pt, Au, Ag, Pd, Al, B, Ga, Si, and Ge.

5. The p-MTJ of claim 1 wherein one or both of FL1 and FL2 is one or more of Co, Fe, CoFe, CoFeB, CoB, FeB, CoFeNi, and CoFeNiB.

6. The p-MTJ of claim 1 wherein one or both of FL1 and FL2 is comprised of a high Ku material having inherent PMA which is a Heusler alloy that is Ni 2 MnZ, Pd 2 MnZ, Co 2 MnZ, Fe 2 MnZ, Co 2 FeZ, Mn 3 Ge, or Mn 2 Ga where Z is one of Si, Ge, Al, Ga, In, Sn, and Sb, or an ordered L1 0 or L1 1 material with a composition that is one of MnAl, MnGa, or RT wherein R is Rh, Pd, Pt, Ir, or an alloy thereof, and T is Fe, Co, Ni, or an alloy thereof, or a rare-earth alloy with a TbFeCo, GdCoFe, FeNdB, or SmCo composition.

7. The p-MTJ of claim 1 where FL1 has a thickness t1, and FL2 has a thickness t2 where a sum of t1 and t2 is from 11 Angstroms to 25 Angstroms.

8. The p-MTJ of claim 1 wherein the Hk enhancing layer is a single layer or a laminate comprised of an oxide or oxynitride of one or more of Mg, Si, Sr, Ti, Ba, Ca, La, Al, Mn, V, and Hf, and has a resistance×area (RA) product less than a RA product of the tunnel barrier layer.

9. The p-MTJ of claim 1 further comprising a seed layer formed on a substrate, to yield a seed layer/PL/tunnel barrier layer/FL/Hk enhancing layer/NCL stack in a bottom spin valve configuration.

10. The p-MTJ of claim 1 further comprising a seed layer formed on a substrate, and a capping layer (CL) on the PL to yield a seed layer/NCL/Hk enhancing layer/FL/tunnel barrier layer/PL/CL stack in a top spin valve configuration.

11. The p-MTJ of claim 1 wherein the p-MTJ is incorporated in a magnetic random access memory (MRAM), spin transfer torque (STT)-MRAM, spin orbit torque (SOT)-MRAM, spin torque oscillator, Spin Hall Effect device, magnetic sensor, or a biosensor.

12. The p-MTJ of claim 1 wherein the NL is comprised of a metal nitride (M1N) or metal oxynitride (M1ON) where M1 is one or more of Ti, V, Cr, Zr, Nb, Mo, Hf, Ta, W, and Si.

13. The p-MTJ of claim 1 wherein the NL has a M2M3N or M2M3ON composition where M2 is one of B, Al, Si, Ga, In, and TI, and M3 is one or more of Pt, Au, Ag, Mg, Ca, Sr, Ba, Sc, Y, La, Co, Fe, Mn, Ru, Rh, Ir, Ni, Pd, Zn, Cu, Ti, V, Cr, Zr, Nb, Mo, Hf, Ta, and W such that the NL is a conductive alloy layer, or has M3 conductive channels formed in a M2N or M2ON insulating matrix.

14. The p-MTJ of claim 1 wherein the buffer layer is a single layer or multilayer that is one or more of Mo, W, Ru, Nb, Ta, Cr, Pt, Cu, Au, Ag, Zn, V, Cd, Sn, Ir, Mn, Rh, Co, Fe, CoFe, CoB, FeB, CoFeNi, and CoFeNiB.

Assignees

• Headway Tech Inc

Inventors

• Guisan Santiago Serrano
• Thomas Luc
• IWATA Jodi Mari
• Jan Guenole
• Tong Ru-Ying

Classifications

• H10N50/85 Primary

  Materials of the active region · CPC title

• G11C11/161 Primary

  details concerning the memory cell structure, e.g. the layers of the ferromagnetic memory cell · CPC title

• H01L43/10 Primary

  Electricity · mapped topic

• H01L43/04

  Electricity · mapped topic

• H01L43/14

  Electricity · mapped topic