# US 8,541,855 B2 · Co/Ni multilayers with improved out-of-plane anisotropy for magnetic device applications

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- Number: US 8,541,855 B2
- Document ID: US8541855B2
- Status: Granted
- Kind: B2
- Application number: 13/068,398
- Filed: 2011-05-10
- Published: 2012-11-15
- Granted: 2013-09-24
- Earliest claimed: 2011-05-10
- Assignees: MagIC Technologies, Inc.
- Applicants: Guenole Jan; Witold Kula; Ru Ying Tong; Yu Jen Wang
- Inventors: Guenole Jan; Witold Kula; Ru Ying Tong; Yu Jen Wang
- Web page: https://patentgrep.com/patent/US8541855B2

## CPC

- H10N 50/85: Materials of the active region
- G01R 33/098: {comprising tunnel junctions, e.g. tunnel magnetoresistance sensors}
- G01R 33/1284: {Spin resolved measurements; Influencing spins during measurements, e.g. in spintronics devices}
- G11B 5/1278: {specially adapted for magnetisations perpendicular to the surface of the record carrier}
- G11C 11/161: {details concerning the memory cell structure, e.g. the layers of the ferromagnetic memory cell}
- H10N 50/01: Manufacture or treatment
- H10N 50/10: Magnetoresistive devices
- H10N 50/80: Constructional details
- G11B 5/3909: {Arrangements using a magnetic tunnel junction}
- H10N: ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
- G01R: MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES (indicating correct tuning of resonant circuits H03J3/12)
- G11B: INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER (recording measured values in a way that does not require playback through a transducer G01D9/00; recording or playback apparatus using mechanically marked tape, e.g. punched paper tape, or using unit records, e.g. punched or magnetically marked cards G06K; transferring data from one type of record carrier to another G06K1/18; circuits for coupling output of reproducer to radio receiver H04B1/20; gramophone pick-ups or like acoustic electromechanical transducers or circuits therefor H04R)
- G11C: STATIC STORES (semiconductor memory devices H10B)

## Abstract

A MTJ for a spintronic device is disclosed and includes a thin seed layer that enhances perpendicular magnetic anisotropy (PMA) in an overlying laminated layer with a (Co/Ni)n composition or the like where n is from 2 to 30. The seed layer is preferably NiCr, NiFeCr, Hf, or a composite thereof with a thickness from 10 to 100 Angstroms. Furthermore, a magnetic layer such as CoFeB may be formed between the laminated layer and a tunnel barrier layer to serve as a transitional layer between a (111) laminate and (100) MgO tunnel barrier. There may be a Ta insertion layer between the CoFeB layer and laminated layer to promote (100) crystallization in the CoFeB layer. The laminated layer may be used as a reference layer, dipole layer, or free layer in a MTJ. Annealing between 300° C. and 400° C. may be used to further enhance PMA in the laminated layer.

## Claims

### Claim 1

A magnetic element, comprising:
(a) a seed layer that is one of Hf, NiCr, NiFeCr, Hf/NiCr, Hf/NiFeCr, NiCr/Hf, or NiFeCr/Hf that enhances perpendicular magnetic anisotropy (PMA) in an overlying laminated layer; and
(b) the laminated layer having intrinsic PMA and comprising a multilayer stack of two metals, a metal and alloy, or two alloys represented by (A1/A2)n where A1 is a first metal or alloy, A2 is a second metal or alloy, and n is the number of laminates in the stack, the laminated layer contacts a top surface of the seed layer, or the laminated layer has an (A1/C/A2) configuration where C is a non-magnetic spacer.

### Claim 2 (depends on 1)

The magnetic element of claim 1 wherein the seed layer has a thickness from about 10 to 300 Angstroms.

### Claim 3 (depends on 1)

The magnetic element of claim 1 wherein the seed layer has a Hf/NiCr, Hf/NiFeCr, NiFeCr/Hf, or NiCr/Hf configuration and a thickness of the NiCr layer or the NiFeCr layer is greater than a thickness of the Hf layer.

### Claim 4 (depends on 1)

The magnetic element of claim 1 wherein A1 is a first metal or alloy selected from one or more of Co, Ni, and Fe; A2 is a second metal or alloy selected from one or more of Co, Fe, Ni, Pt, and Pd, and A1 is unequal to A2.

### Claim 5 (depends on 1)

The magnetic element of claim 1 wherein the seed layer and laminated layer are formed in a magnetic tunnel junction (MTJ) having a seed layer/reference layer/tunnel barrier/free layer configuration, the laminated layer is part of the reference layer.

### Claim 6 (depends on 5)

The magnetic element of claim 5 wherein the reference layer further comprises a magnetic layer formed between the laminated layer and the tunnel barrier to increase the magnetoresistive (MR) ratio in the MTJ, the magnetic layer interfaces with the tunnel barrier and has PMA with a magnetic moment in the same direction as the PMA in the laminated layer.

### Claim 7 (depends on 6)

The magnetic element of claim 6 wherein the magnetic layer is CoFeB, CoFe, or combinations thereof with a thickness from about 6 to 14 Angstroms.

### Claim 8

A magnetic tunnel junction (MTJ) having a reference layer/tunnel barrier/free layer/spacer/seed layer/laminated dipole layer configuration wherein the seed layer is one of Hf, NiCr, NiFeCr, Hf/NiCr, Hf/NiFeCr, NiCr/Hf, or NiFeCr/Hf that enhances perpendicular magnetic anisotropy (PMA) in the overlying laminated dipole layer; the laminated dipole layer contacts a top surface of the seed layer, and has intrinsic PMA and comprises a multilayer stack of two metals, a metal and alloy, or two alloys represented by (A1/A2)n where A1 is a first metal or alloy, A2 is a second metal or alloy, and n is the number of laminates in the stack, or the laminated layer has an (A1/C/A2) configuration where C is a non-magnetic spacer.

### Claim 9 (depends on 8)

The MTJ of claim 8 wherein A1 is a first metal or alloy selected from one or more of Co, Ni, and Fe; A2 is a second metal or alloy selected from one or more of Co, Fe, Ni, Pt, and Pd, and A1 is unequal to A2.

### Claim 10 (depends on 8)

The MTJ of claim 8 wherein the seed layer has a Hf/NiCr, Hf/NiFeCr, NiFeCr/Hf, or NiCr/Hf configuration and a thickness of the NiCr layer or the NiFeCr layer is greater than a thickness of the Hf layer.

### Claim 11

A magnetic tunnel junction (MTJ) having a seed layer/laminated free layer/tunnel barrier/reference layer configuration wherein the seed layer is one of Hf, NiCr, NiFeCr, Hf/NiCr, Hf/NiFeCr, NiCr/Hf, or NiFeCr/Hf that enhances perpendicular magnetic anisotropy (PMA) in the overlying laminated free layer; the laminated free layer contacts a top surface of the seed layer and comprises a multilayer stack of two metals, a metal and alloy, or two alloys represented by (A1/A2)n where A1 is a first metal or alloy, A2 is a second metal or alloy, and n is the number of laminates in the stack, or the laminated free layer has an (A1/C/A2) configuration where C is a non-magnetic spacer.

### Claim 12 (depends on 11)

The MTJ of claim 11 wherein the laminated free layer further comprises a magnetic layer formed between the laminated free layer and the tunnel barrier to increase the magnetoresistive (MR) ratio in the MTJ, the magnetic layer interfaces with the tunnel barrier and has PMA with a magnetic moment in the same direction as the PMA in the laminated free layer.

### Claim 13 (depends on 11)

The MTJ of claim 11 wherein A1 is a first metal or alloy selected from one or more of Co, Ni, and Fe; A2 is a second metal or alloy selected from one or more of Co, Fe, Ni, Pt, and Pd, and A1 is unequal to A2.

### Claim 14 (depends on 11)

The MTJ of claim 11 wherein the seed layer has a Hf/NiCr, Hf/NiFeCr, NiFeCr/Hf, or NiCr/Hf configuration and a thickness of the NiCr layer or the NiFeCr layer is greater than a thickness of the Hf layer.