# US 10,873,025 B2 · Formation of correlated electron material (CEM) device via dopant deposition and anneal

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- Number: US 10,873,025 B2
- Document ID: US10873025B2
- Status: Granted
- Kind: B2
- Application number: 16/572,521
- Filed: 2019-09-16
- Published: 2020-01-09
- Granted: 2020-12-22
- Earliest claimed: 2018-03-28
- Assignees: Arm Limited
- Applicants: Cerfe Labs, Inc.
- Inventors: Lucian Shifren; Carlos Alberto Paz de Araujo; Jolanta Bozena Celinska; Christopher Randolph McWilliams
- Web page: https://patentgrep.com/patent/US10873025B2

## CPC

- H10N 70/883: {Oxides or nitrides}
- H10B 63/845: {the switching components being connected to a common vertical conductor}
- H10N 70/021: {Formation of switching materials, e.g. deposition of layers}
- H10N 70/023: {by chemical vapor deposition, e.g. MOCVD, ALD}
- H10N 70/041: {Modification of switching materials after formation, e.g. doping (shaping H10N70/061)}
- H10N 70/20: Multistable switching devices, e.g. memristors
- H10N 70/823: {adapted for essentially horizontal current flow, e.g. bridge type devices}
- H10N 70/826: {adapted for essentially vertical current flow, e.g. sandwich or pillar type devices}
- H10N 70/8833: {Binary metal oxides, e.g. TaOx}
- H10N: ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
- H10B: ELECTRONIC MEMORY DEVICES

## Abstract

Subject matter disclosed herein may relate to fabrication of a correlated electron material (CEM) switch. In particular embodiments, formation of a CEM switch may comprise depositing metal layers, such layers of a transition metal, over a conductive substrate. Dopant layers may subsequently be deposited on the layers of the transition metal, followed by annealing of the layers of transition metal and dopant layers. Responsive to annealing, dopant from the dopant layers may diffuse into the one or more layers of transition metal, thereby forming a CEM.

## Claims

### Claim 1

A method of constructing a switching device, comprising:
depositing in a chamber one or more layers of a first material over a conductive substrate;
depositing one or more layers of a second material having an atomic concentration of metal atoms over the one or more layers of the first material;
depositing one or more layers of a third material over the one or more layers of the second material; and
annealing the one or more layers of the first material, the one or more layers of the second material and the one or more layers of the third material to diffuse one or more dopants from the one or more layers of the first material and the one or more layers of the third material into the one or more layers of the second material to form a first correlated electron material (CEM) and to impart a particular distribution of an atomic concentration of the one or more dopants within the one or more layers of the second material to provide a switching capability.

### Claim 2 (depends on 1)

The method of claim 1, wherein the one or more layers of the first material or the one or more layers of the third material, or a combination thereof, are deposited to respective particular thicknesses selected to impart the particular distribution of the atomic concentration of the one or more dopants in the one or more layers of the second material from the annealing.

### Claim 3 (depends on 2)

The method of claim 2, wherein the particular distribution of the atomic concentration of the one or more dopants in the one or more layers of the second material imparted from the annealing varies at least in part as a function of separation from the conductive substrate.

### Claim 4 (depends on 2)

The method of claim 2, wherein the particular distribution of the atomic concentration of the one or more dopants in the one or more layers of the second material decreases with an increase in distance from the conductive substrate.

### Claim 5 (depends on 1)

The method of claim 1, further comprising forming a capping layer over the one or more layers of the third material;
wherein the particular distribution of the atomic concentration of the one or more dopants in the one or more layers of the second material decreases with an increase in separation from the conductive substrate until a reduced concentration is imparted at a particular location within the one or more layers of the second material, and wherein the particular distribution of the atomic concentration of the one or more dopants in the one or more layers of the second material increases from the reduced concentration imparted at the particular location within the one or more layers of the second material with a decrease in separation from the particular location to the capping layer.

### Claim 6 (depends on 1)

The method of claim 1, wherein the conductive substrate comprises an atomic concentration of at least 90.0% of titanium.

### Claim 7 (depends on 1)

The method of claim 1, wherein the depositing the one or more layers of the first material comprises depositing the one or more layers of the first material to a thickness of 0.1 Å to 250.0 Å.

### Claim 8 (depends on 7)

The method of claim 7, wherein the first material comprises an atomic concentration of at least 90.0% of nickel.

### Claim 9 (depends on 1)

The method of claim 1, wherein the depositing the one or more layers of the second material comprises depositing the one or more layers of the second material to a thickness of 15.0 Å to 1500.0 Å.

### Claim 10 (depends on 1)

The method of claim 1, wherein the second material comprises a metal, metal oxide or metal compound, or a combination thereof.

### Claim 11 (depends on 1)

The method of claim 1, wherein the second material comprises an atomic concentration of at least about 90.0% of nickel.

### Claim 12 (depends on 1)

The method of claim 1, wherein the third material comprises a similar material to the first material.

### Claim 13 (depends on 1)

The method of claim 1, wherein the third material comprises a different material from the first material.

### Claim 14 (depends on 1)

The method of claim 1, wherein the annealing the one or more first layers of the first material, the one or more layers of the second material and the one or more layers of the third material comprises annealing the one or more layers of the first material, the one or more layers of the second material and the one or more layers of the third material in an oxygen-containing environment.

### Claim 15 (depends on 14)

The method of claim 14, further comprising forming the oxygen-containing environment via substantially filling the chamber with carbon dioxide (CO2), carbon monoxide (CO), oxygen (O2), ozone (O3+) or nitrosyl (NO), or any combination thereof.

### Claim 16

A switching device, comprising: a structure comprising:
a conductive substrate; and
one or more layers of a first material positioned over the conductive substrate; and
a capping layer positioned over the one or more layers of the first material;
wherein the atomic concentration of a dopant in the one or more layers of the first material to increase with an increase in separation from the conductive substrate to a particular location within the one or more layers of the first material, and wherein the atomic concentration of the dopant in the one or more layers of the first material to decrease from the particular location within the one or more layers of the first material with a decrease in separation from the particular location to the capping layer.