# US 10,483,320 B2 · Magnetoresistive stack with seed region and method of manufacturing the same

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- Number: US 10,483,320 B2
- Document ID: US10483320B2
- Status: Granted
- Kind: B2
- Application number: 16/195,178
- Filed: 2018-11-19
- Published: 2019-04-25
- Granted: 2019-11-19
- Earliest claimed: 2015-12-10
- Assignees: Everspin Technologies, Inc.
- Applicants: Everspin Technologies, Inc.
- Inventors: Jijun Sun; Sanjeev Aggarwal; Han-Jong Chia; Jon M. Slaughter; Renu Whig
- Web page: https://patentgrep.com/patent/US10483320B2

## CPC

- H10B 61/00: Magnetic memory devices, e.g. magnetoresistive RAM [MRAM] devices
- G11B 5/3909: {Arrangements using a magnetic tunnel junction}
- G11C 11/1673: {Reading or sensing circuits or methods}
- H10N 50/01: Manufacture or treatment
- H10N 50/10: Magnetoresistive devices
- H10N 50/80: Constructional details
- H10N 50/85: Materials of the active region
- H10B: ELECTRONIC MEMORY DEVICES
- 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)
- H10N: ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR

## Abstract

A magnetoresistive stack/structure and method of manufacturing same comprising wherein the stack/structure includes a seed region, a fixed magnetic region disposed on and in contact with the seed region, a dielectric layer(s) disposed on the fixed magnetic region and a free magnetic region disposed on the dielectric layer(s). In one embodiment, the seed region comprises an alloy including nickel and chromium having (i) a thickness greater than or equal to 40 Angstroms (+/−10%) and less than or equal to 60 Angstroms (+/−10%), and (ii) a material composition or content of chromium within a range of 25-60 atomic percent (+/−10%) or 30-50 atomic percent (+/−10%).

## Claims

### Claim 1

A magnetoresistive stack comprising:
a seed region disposed at least partially on an electrically conductive material, wherein the seed region includes an alloy layer including at least 99 atomic percent (at. %) of nickel and chromium and comprises:
a first alloy layer including nickel and chromium in contact with the electrically conductive material;
a second alloy layer including nickel and chromium in contact with a fixed magnetic region; and
at least one auxiliary layer disposed between the first alloy layer and the second alloy layer;
the fixed magnetic region disposed at least partially on and in contact with the seed region, wherein the fixed magnetic region includes a synthetic antiferromagnetic structure comprising:
a first ferromagnetic region disposed on and in contact with the seed region;
a coupling layer disposed on and in contact with the first ferromagnetic region; and
a second ferromagnetic region disposed on and in contact with the coupling layer;
one or more dielectric layers disposed on and in contact with the second ferromagnetic region; and
a free magnetic region disposed on the one or more dielectric layers.

### Claim 2 (depends on 1)

The magnetoresistive stack of claim 1, wherein the alloy layer includes at least 30 at. % chromium (Cr).

### Claim 3 (depends on 1)

The magnetoresistive stack of claim 1, wherein the seed region further includes at least one auxiliary layer.

### Claim 4 (depends on 1)

The magnetoresistive stack of claim 1, wherein the alloy layer is in contact with the electrically conductive material.

### Claim 5 (depends on 1)

The magnetoresistive stack of claim 1, wherein the seed region further includes at least one auxiliary layer in contact with the electrically conductive material.

### Claim 6 (depends on 1)

The magnetoresistive stack of claim 1, wherein the seed region further includes at least one auxiliary layer in contact with the electrically conductive material, and wherein the auxiliary layer has a same composition as a composition of the electrically conductive material.

### Claim 7 (depends on 1)

The magnetoresistive stack of claim 1, wherein the seed region further includes at least one auxiliary layer, and wherein the alloy layer is in contact with the fixed magnetic region.

### Claim 8 (depends on 1)

The magnetoresistive stack of claim 1, wherein the seed region further includes at least one auxiliary layer in contact with the fixed magnetic region.

### Claim 9 (depends on 1)

The magnetoresistive stack of claim 1, further comprising a dusting layer disposed on the seed region, wherein the dusting layer includes at least one of molybdenum, magnesium, iron, platinum, ruthenium, or an alloy including cobalt and iron.

### Claim 10 (depends on 1)

The magnetoresistive stack of claim 1, wherein the alloy layer has a thickness of 10 Å to 25 Å.

### Claim 11

A magnetoresistive stack comprising:
a seed region disposed at least partially on an electrically conductive material, wherein the seed region includes:
a first alloy layer including nickel and chromium in contact with the electrically conductive material;
a second alloy layer including nickel and chromium in contact with a dusting layer; and
at least one auxiliary layer disposed between the first alloy layer and the second alloy layer;
the dusting layer disposed on the seed region, wherein the dusting layer includes at least one of molybdenum, magnesium, iron, platinum, ruthenium, or an alloy including cobalt and iron;
a fixed magnetic region disposed on and in contact with the dusting layer, wherein the fixed magnetic region comprises:
a first ferromagnetic region disposed on and in contact with the dusting layer;
a coupling layer disposed on and in contact with the first ferromagnetic region; and
a second ferromagnetic region disposed on and in contact with the coupling layer;
one or more dielectric layers disposed on and in contact with the second ferromagnetic region; and
a free magnetic region disposed on the one or more dielectric layers.

### Claim 12 (depends on 11)

The magnetoresistive stack of claim 11, wherein the dusting layer includes an alloy including cobalt, iron, and boron.

### Claim 13 (depends on 11)

The magnetoresistive stack of claim 11, wherein the seed region has a thickness of greater than or equal to 30 Å.

### Claim 14 (depends on 11)

The magnetoresistive stack of claim 11, wherein the seed region comprises an alloy layer including nickel and at least 30 atomic percent (at. %) chromium.

### Claim 15 (depends on 11)

The magnetoresistive stack of claim 11, wherein the seed region comprises an alloy layer including at least 99 atomic percent (at. %) of nickel and chromium.

### Claim 16 (depends on 11)

The magnetoresistive stack of claim 11, wherein the dusting layer has a thickness of 1 Å to 12Å.

### Claim 17 (depends on 11)

The magnetoresistive stack of claim 11, wherein the first ferromagnetic region comprises at least one of nickel, cobalt, or platinum.

### Claim 18 (depends on 11)

The magnetoresistive stack of claim 11, wherein the coupling layer includes ruthenium.

### Claim 19

A method of manufacturing a magnetoresistive stack, the method comprising:
depositing a seed region, including:
depositing a first alloy layer including nickel and chromium;
depositing a second alloy layer including nickel and chromium in contact with a fixed magnetic region; and
depositing at least one auxiliary layer disposed between the first alloy layer and the second alloy layer;
depositing a dusting layer of at least one of molybdenum, magnesium, iron, platinum, or ruthenium on and in contact with the seed region;
depositing the fixed region including a synthetic antiferromagnetic structure on and in contact with the dusting layer, wherein depositing the synthetic antiferromagnetic structure comprises:
depositing a first ferromagnetic region on and in contact with the dusting layer;
depositing a coupling layer on and in contact with the first ferromagnetic region; and
depositing a second ferromagnetic region on and in contact with the coupling layer;
depositing one or more dielectric layers on the second ferromagnetic region; and
depositing a free magnetic region on the one or more dielectric layers.

### Claim 20 (depends on 19)

The method of claim 19, wherein depositing a first alloy layer, a second alloy layer, or both, comprises:
depositing at least one alloy layer including at least 99 atomic percent (at. %) of nickel and chromium.

### Claim 21 (depends on 19)

The method of claim 19, further comprising:
depositing a reference layer on and in contact with the synthetic antiferromagnetic structure.