# US 12,765,266 B2 · Magnetic tunnel junction (MTJ) having a diffusion blocking spacer layer

> Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt

- Number: US 12,765,266 B2
- Document ID: US12765266B2
- Status: Granted
- Kind: B2
- Application number: 18/164,845
- Filed: 2023-02-06
- Published: 2024-08-08
- Granted: 2026-10-13
- Earliest claimed: 2023-02-06
- Assignees: Taiwan Semiconductor Manufacturing Company, Ltd.
- Applicants: Taiwan Semiconductor Manufacturing Company, Ltd.
- Inventors: Kuo-Feng Huang; Bo-Hung Lin; Harry-Haklay Chuang; Kuei-Hung Shen; Ding-Shuo Wang; Yu-Jen Wang
- Web page: https://patentgrep.com/patent/US12765266B2

## CPC

- H10N 50/10: Magnetoresistive devices
- G11C 11/161: {details concerning the memory cell structure, e.g. the layers of the ferromagnetic memory cell}
- H01F 10/3254: {the spacer being semiconducting or insulating, e.g. for spin tunnel junction [STJ]}
- H10N 50/01: Manufacture or treatment
- H10N 50/85: Materials of the active region
- H10N: ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
- G11C: STATIC STORES (semiconductor memory devices H10B)
- H01F: MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES

## Abstract

An integrated chip including a reference magnetic layer and a barrier layer over the reference magnetic layer. A first free magnetic layer is over the barrier layer. A second free magnetic layer is over the first free magnetic layer. A spacer layer is between the first free magnetic layer and the second free magnetic layer. The spacer layer includes magnesium and a transition metal. An atomic ratio of the magnesium to the transition metal ranges from 15% to 80%.

## Claims

### Claim 1

A method for forming an integrated chip, the method comprising:
depositing a reference magnetic layer over a substrate;
depositing a barrier layer over the reference magnetic layer;
depositing a first free magnetic layer over the barrier layer, the first free magnetic layer comprising boron;
depositing a spacer layer over the first free magnetic layer, the spacer layer comprising magnesium and a transition metal, wherein an atomic ratio of the magnesium to the transition metal ranges from 15% to 80%; and
depositing a second free magnetic layer over the spacer layer,
wherein boron atoms in the first free magnetic layer diffuse toward the spacer layer after the spacer layer is deposited, and wherein a concentration of boron atoms in the first free magnetic layer decreases as a distance from the spacer layer increases after the spacer layer is deposited.

### Claim 2 (depends on 1)

The method of claim 1, wherein the depositing of the spacer layer comprises sputtering the magnesium over the first free magnetic layer using a first sputtering gun and concurrently sputtering the transition metal over the first free magnetic layer using a second sputtering gun.

### Claim 3 (depends on 1)

The method of claim 1, wherein the depositing of the spacer layer comprises alternating between sputtering the magnesium over the first free magnetic layer using a first sputtering gun and sputtering the transition metal over the first free magnetic layer using a second sputtering gun.

### Claim 4 (depends on 1)

The method of claim 1, wherein the depositing of the spacer layer comprises sputtering both the magnesium and the transition metal using a sputtering gun having a target layer comprising both the magnesium and the transition metal.

### Claim 5 (depends on 1)

The method of claim 1, wherein the depositing of the spacer layer comprises depositing a first spacer film over the first free magnetic layer and depositing a second spacer film over and contacting the first spacer film, the first spacer film comprising a first material and the second spacer film comprising a second material, different than the first material.

### Claim 6 (depends on 5)

The method of claim 5, wherein the depositing of the spacer layer further comprises depositing a third spacer film over and contacting the second spacer film, the third spacer film comprising a third material, different than the second material.

### Claim 7 (depends on 1)

The method of claim 1,
wherein boron atoms from the first free magnetic layer diffuse into the spacer layer after the spacer layer is deposited, and wherein a concentration of boron atoms in the spacer layer decreases as a distance from the first free magnetic layer increases after the spacer layer is deposited.

### Claim 8

A method for forming an integrated chip, the method comprising:
forming a magnetic tunnel junction (MTJ) over a substrate, the forming of the MTJ comprising:
depositing a reference magnetic layer over the substrate;
depositing a barrier layer over the reference magnetic layer;
depositing a first free magnetic layer over the barrier layer, the first free magnetic layer comprising boron;
depositing a spacer layer over the first free magnetic layer, the spacer layer comprising magnesium and a transition metal; and
depositing a second free magnetic layer over the spacer layer; and
forming a plurality of metal interconnects over the MTJ, wherein the MTJ has a first energy barrier before the forming of the metal interconnects over the MTJ, and wherein the MTJ has a second energy barrier, different than the first energy barrier, after the forming of the metal interconnects over the MTJ, and wherein a difference between the first energy barrier and the second energy barrier is less than 10%,
wherein boron atoms from the first free magnetic layer diffuse into the spacer layer after the plurality of metal interconnects are formed so that the spacer layer further comprises boron and a concentration of boron atoms in the spacer layer decreases as a distance from the first free magnetic layer increases.

### Claim 9 (depends on 8)

The method of claim 8, wherein the MTJ is exposed to temperatures greater than 400 degrees Celsius during the forming of the metal interconnects.

### Claim 10 (depends on 8)

The method of claim 8, wherein a thickness of the spacer layer ranges from 5%-100% of a sum of a thickness of the first free magnetic layer and a thickness of the second free magnetic layer.

### Claim 11 (depends on 8)

The method of claim 8, wherein boron atoms in the first free magnetic layer diffuse toward the spacer layer after the plurality of metal interconnects are formed so that a concentration of boron atoms in the first free magnetic layer decreases as a distance from the spacer layer increases.

### Claim 12

A method for forming an integrated chip, the method comprising:
depositing a reference magnetic layer on a first electrode layer;
depositing a barrier layer on the reference magnetic layer;
depositing a first free magnetic layer on the barrier layer;
depositing a first spacer layer on the first free magnetic layer, the first spacer layer comprising one or both of magnesium and a first transition metal;
depositing a second spacer layer on the first spacer layer, the second spacer layer comprising one or both of magnesium and a second transition metal, wherein at least one of the first spacer layer and the second spacer layer comprises magnesium, and wherein at least one of the first spacer layer and the second spacer layer comprises transition metal, and wherein the first spacer layer extends from a top surface of the first free magnetic layer to a bottom surface of the second spacer layer;
depositing a second free magnetic layer over the second spacer layer; and
depositing a cap layer on the second free magnetic layer; and
depositing a second electrode layer on the cap layer.

### Claim 13 (depends on 12)

The method of claim 12, wherein depositing the first spacer layer comprises sputtering magnesium on the first free magnetic layer using a first sputtering gun, and wherein depositing the second spacer layer comprises sputtering the second transition metal directly on the magnesium of the first spacer layer using a second sputtering gun.

### Claim 14 (depends on 12)

The method of claim 12, wherein depositing the first spacer layer comprises sputtering the first transition metal on the first free magnetic layer using a first sputtering gun, and wherein depositing the second spacer layer comprises sputtering magnesium directly on the first transition metal using a second sputtering gun.

### Claim 15 (depends on 12)

The method of claim 12, wherein depositing the first spacer layer comprises sputtering magnesium using a first sputtering gun and concurrently sputtering the first transition metal using a second sputtering gun, and wherein depositing the second spacer layer comprises sputtering magnesium using the first sputtering gun and concurrently sputtering the second transition metal using a third sputtering gun, and wherein the second transition metal is different than the first transition metal.

### Claim 16 (depends on 12)

The method of claim 12, wherein depositing the first spacer layer comprises sputtering magnesium and the first transition metal using a first sputtering gun, and wherein depositing the second spacer layer comprises sputtering magnesium and the second transition metal using a second sputtering gun, and wherein the second transition metal is different than the first transition metal.

### Claim 17 (depends on 12)

The method of claim 12, further comprising:
depositing a third spacer layer directly on the second spacer layer, wherein the second free magnetic layer is deposited on the third spacer layer, and wherein the first spacer layer consists essentially of magnesium, the second spacer layer consists essentially of the second transition metal, and the third spacer layer consists essentially of magnesium.

### Claim 18 (depends on 12)

The method of claim 12, further comprising:
depositing a third spacer layer directly on the second spacer layer, wherein the second free magnetic layer is deposited on the third spacer layer, and wherein the first spacer layer consists essentially of the first transition metal, the second spacer layer consists essentially of magnesium, and the third spacer layer consists essentially of a third transition metal.

### Claim 19 (depends on 12)

The method of claim 12, further comprising:
depositing a third spacer layer directly on the second spacer layer, wherein the second free magnetic layer is deposited on the third spacer layer, wherein the first spacer layer comprises magnesium and the first transition metal, the second spacer layer comprises magnesium and the second transition metal, and the third spacer layer comprises magnesium and a third transition metal, and wherein the second transition metal is different than the first transition metal and the third transition metal.

### Claim 20 (depends on 12)

The method of claim 12, wherein the first spacer layer and the second spacer layer both comprise boron, and wherein a boron concentration in the first spacer layer is greater than a boron concentration in the second spacer layer.