# US 10,121,824 B2 · Magnetic structures, semiconductor structures, and semiconductor devices

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- Number: US 10,121,824 B2
- Document ID: US10121824B2
- Status: Granted
- Kind: B2
- Application number: 15/642,577
- Filed: 2017-07-06
- Published: 2017-10-26
- Granted: 2018-11-06
- Earliest claimed: 2012-06-19
- Assignees: Micron Technology, Inc.
- Applicants: Micron Technology, Inc.
- Inventors: Wayne I. Kinney; Witold Kula; Stephen J. Kramer
- Web page: https://patentgrep.com/patent/US10121824B2

## CPC

- H10B 61/00: Magnetic memory devices, e.g. magnetoresistive RAM [MRAM] devices
- G11C 11/161: {details concerning the memory cell structure, e.g. the layers of the ferromagnetic memory cell}
- G11C 11/1673: {Reading or sensing circuits or methods}
- G11C 11/1675: {Writing or programming circuits or methods}
- H01F 10/3218: {Exchange coupling of magnetic films via an antiferromagnetic interface (H01F10/3268 takes precedence)}
- H10N 50/10: Magnetoresistive devices
- H10N 50/80: Constructional details
- H10N 50/85: Materials of the active region
- H01F 10/329: {Spin-exchange coupled multilayers wherein the magnetisation of the free layer is switched by a spin-polarised current, e.g. spin torque effect}
- H10B 61/22: {of the field-effect transistor [FET] type}
- H10B: ELECTRONIC MEMORY DEVICES
- G11C: STATIC STORES (semiconductor memory devices H10B)
- H01F: MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
- H10N: ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR

## Abstract

Memory cells are disclosed. Magnetic regions within the memory cells include an alternating structure of magnetic sub-regions and coupler sub-regions. The coupler material of the coupler sub-regions antiferromagnetically couples neighboring magnetic sub-regions and effects or encourages a vertical magnetic orientation exhibited by the neighboring magnetic sub-regions. Neighboring magnetic sub-regions, spaced from one another by a coupler sub-region, exhibit oppositely directed magnetic orientations. The magnetic and coupler sub-regions may each be of a thickness tailored to form the magnetic region in a compact structure. Interference between magnetic dipole fields emitted from the magnetic region on switching of a free region in the memory cell may be reduced or eliminated. Also disclosed are semiconductor device structures, spin torque transfer magnetic random-access memory (STT-MRAM) systems, and methods of fabrication.

## Claims

### Claim 1

A semiconductor structure comprising:
a magnetic structure comprising:
magnetic regions, the magnetic regions comprising:
a free region exhibiting a switchable vertical magnetic orientation; and
a fixed region exhibiting a fixed vertical magnetic orientation, the free region having a horizontal surface defining a smaller surface area than a surface area defined by a horizontal surface of the fixed region,
at least one of the magnetic regions comprising an alternating structure of magnetic sub-regions and coupler sub-regions, wherein the magnetic sub-regions of the alternating structure exhibit oppositely directed vertical magnetic orientations; and
a non-magnetic region between the free region and the fixed region.

### Claim 2 (depends on 1)

The semiconductor structure of claim 1, wherein each coupler sub-region of the coupler sub-regions is antiferromagnetically coupled to at least one neighboring magnetic sub-region of the magnetic sub-regions.

### Claim 3 (depends on 1)

The semiconductor structure of claim 1, wherein each of the coupler sub-regions is directly between two magnetic sub-regions.

### Claim 4 (depends on 1)

The semiconductor structure of claim 1, wherein each of the coupler sub-regions effects anti-parallel coupling in at least one neighboring magnetic sub-region.

### Claim 5 (depends on 1)

The semiconductor device of claim 1, wherein the magnetic sub-regions each define a height less than a height defined by each of the coupler sub-regions.

### Claim 6 (depends on 1)

The semiconductor structure of claim 1, wherein the fixed region comprises the alternating structure of the magnetic sub-regions and the coupler sub-regions.

### Claim 7 (depends on 1)

The semiconductor structure of claim 1, wherein each of the free region and the fixed region comprises the alternating structure of the magnetic sub-regions and the coupler sub-regions.

### Claim 8

A magnetic structure comprising:
a magnetic core comprising:
magnetic regions, the magnetic regions comprising:
a free region exhibiting a switchable vertical magnetic orientation; and
a fixed region exhibiting a fixed vertical magnetic orientation,
at least one of the magnetic regions comprising an alternating structure of magnetic sub-regions and coupler sub-regions, wherein the fixed region comprises a superlattice structure of the magnetic sub-regions and the coupler sub-regions; and
a non-magnetic region between the free region and the fixed region, the non-magnetic region being electrically insulative.

### Claim 9 (depends on 8)

The magnetic structure of claim 8, wherein a lateral dimension of the free region is smaller than a lateral dimension of the fixed region.

### Claim 10 (depends on 8)

The magnetic structure of claim 8, wherein the magnetic cell core is configured to emit a stronger magnetic dipole field near sidewalls of the fixed region.

### Claim 11 (depends on 8)

The magnetic structure of claim 8, wherein the free region and the fixed region comprise alternating structures of magnetic sub-regions and coupler sub-regions and the number of magnetic sub-regions in the free region is less than the number of magnetic sub-regions in the fixed region.

### Claim 12 (depends on 8)

The magnetic structure of claim 8, wherein each of the coupler sub-regions comprises ruthenium (Ru), rhodium (Rh), or combinations thereof.

### Claim 13 (depends on 8)

The magnetic structure of claim 8, wherein the fixed region is free of palladium, platinum, or combinations thereof.

### Claim 14 (depends on 8)

The magnetic structure of claim 8, wherein each of the magnetic sub-regions and the coupler sub-regions has a thickness of less than about one nanometer.

### Claim 15 (depends on 8)

The magnetic structure of claim 8, wherein the magnetic sub-regions each define a height less than a height defined by each of the coupler sub-regions.

### Claim 16 (depends on 8)

The magnetic structure of claim 8, wherein the non-magnetic region comprises a magnetic tunnel junction.

### Claim 17 (depends on 8)

The magnetic structure of claim 8, wherein the non-magnetic region comprises a spin valve.

### Claim 18 (depends on 8)

The magnetic structure of claim 8, wherein each of the magnetic sub-regions consists of cobalt.

### Claim 19

A semiconductor device, comprising:
magnetic structures, each magnetic structure of the magnetic structures comprising:
at least one magnetic region comprising an alternating structure of magnetic sub-regions and coupler sub-regions, magnetic material of the at least one magnetic region exhibiting a vertical magnetic orientation, neighboring magnetic sub-regions of the alternating structure being antiferromagnetically coupled with one another, wherein each coupler sub-region of the coupler sub-regions comprises one or more of ruthenium and rhodium.

### Claim 20 (depends on 19)

The semiconductor device of claim 19, wherein the alternating structure of magnetic sub-regions and coupler sub-regions comprises the magnetic sub-regions spaced apart from one another by the coupler sub-regions.

### Claim 21 (depends on 19)

The semiconductor device of claim 19, wherein the coupler sub-regions are thicker than the magnetic sub-regions and each magnetic sub-region of the magnetic sub-regions consists of a monolayer of the magnetic material.