# US 12,000,870 B2 · Multi-terminal devices using magnetoresistance elements

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- Number: US 12,000,870 B2
- Document ID: US12000870B2
- Status: Granted
- Kind: B2
- Application number: 17/931,197
- Filed: 2022-09-12
- Published: 2024-03-14
- Granted: 2024-06-04
- Earliest claimed: 2022-09-12
- Assignees: Allegro MicroSystems, LLC
- Applicants: Allegro MicroSystems, LLC
- Inventors: Samridh Jaiswal; Paolo Campiglio; Sundar Chetlur; Maxim Klebanov; Yen Ting Liu
- Web page: https://patentgrep.com/patent/US12000870B2

## CPC

- G01R 15/205: {using magneto-resistance devices, e.g. field plates}
- G01R 33/0052: {Manufacturing aspects; Manufacturing of single devices, i.e. of semiconductor magnetic sensor chips (devices based on galvano-magnetic effect or the like H10N50/85)}
- G01R 19/0092: {Measuring current only}
- G01R 33/098: {comprising tunnel junctions, e.g. tunnel magnetoresistance sensors}
- G11B 5/3909: {Arrangements using a magnetic tunnel junction}
- H10N 50/10: Magnetoresistive devices
- 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)
- H10N: ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR

## Abstract

In one aspect, a sensor includes a first metal layer portion and a second metal layer portion separated by an insulator material; a conductive material layer in electrical contact with the first metal layer portion and the second metal layer portion; and a tunnel magnetoresistance (TMR) element positioned on and in electrical contact with the conductive material layer. A first current is configured to flow from the first metal layer portion, through the conductive material layer, to the second metal layer portion, and a second current is configured to flow from the first metal layer portion, through the conductive material layer, through the TMR element, and exiting through a top of the TMR element.

## Claims

### Claim 1

A sensor comprising:
a first metal layer portion and a second metal layer portion separated by an insulator material;
a conductive material layer in electrical contact with the first metal layer portion and the second metal layer portion; and
a tunnel magnetoresistance (TMR) element positioned on and in electrical contact with the conductive material layer,
wherein a first current is configured to flow from the first metal layer portion, through the conductive material layer, to the second metal layer portion, and
wherein a second current is configured to flow from the first metal layer portion, through the conductive material layer, through the TMR element, and exiting through a top of the TMR element.

### Claim 2 (depends on 1)

The sensor of claim 1, wherein the first current is also configured to flow through a bottom layer of the TMR element.

### Claim 3 (depends on 2)

The sensor of claim 2, wherein the bottom layer of the TMR element is a reference layer.

### Claim 4

A sensor comprising:
a first metal layer portion, a second metal layer portion, and a third metal layer portion each separated by an insulator material;
a conductive material layer in electrical contact with the first, second, and third metal layer portions; and
a tunnel magnetoresistance (TMR) element positioned on and in electrical contact with the conductive layer,
wherein a first current is configured to flow from the first metal layer portion, through the conductive material layer, to the third metal layer portion, and
wherein a second current is configured to flow from the second metal layer portion, through the conductive material layer, through the TMR element, and exiting through a top of the TMR element.

### Claim 5 (depends on 4)

The sensor of claim 4, wherein the conductive material layer includes titanium nitride.

### Claim 6 (depends on 4)

The sensor of claim 4, wherein the first current is also configured to flow through a bottom layer of the TMR element.

### Claim 7 (depends on 4)

The sensor of claim 4, wherein the first current flows through a bottom layer of the TMR element, without passing through a barrier layer of the TMR element, and causes the bottom layer to increase in temperature beyond a blocking temperature of the TMR element such that current-induced degradation of the barrier layer does not occur.

### Claim 8 (depends on 4)

The sensor of claim 4, wherein the first current is controlled to cause a bottom layer of the TMR element to remain at a constant temperature.

### Claim 9 (depends on 4)

The sensor of claim 4, further comprising a thermal diode configured to monitor a temperature of a bottom layer of the TMR element.

### Claim 10 (depends on 9)

The sensor of claim 9, wherein the bottom layer of the TMR element is a reference layer.

### Claim 11 (depends on 4)

The sensor of claim 4, wherein the first current causes a planar magnetic field to be generated in the TMR element in a direction that is perpendicular to a direction of flow of the first current.

### Claim 12 (depends on 4)

The sensor of claim 4, wherein the first current includes a modulation signal configured to modify a magnetic field signal received by the TMR element, and the sensor is configured to demodulate the modified signal to determine the magnetic field signal.

### Claim 13 (depends on 4)

The sensor of claim 4, wherein the conductive material layer is a heavy metal layer that is configured to generate a transversal spin current in the TMR element in response to the first current.

### Claim 14 (depends on 13)

The sensor of claim 13, wherein the transversal spin current causes a resistance associated with the TMR element to change.

### Claim 15 (depends on 14)

The sensor of claim 14, wherein the sensor is configured to measure the first current based on a change in the resistance associated with the TMR element caused by the transversal spin current.

### Claim 16 (depends on 15)

The sensor of claim 15, wherein the change in the resistance is based on a relative orientation between a magnetization of a free layer of the TMR element and a magnetization of a reference layer of the TMR element.

### Claim 17 (depends on 13)

The sensor of claim 13, wherein the heavy metal layer includes one or more of platinum, tantalum, tungsten, and gold.

### Claim 18 (depends on 13)

The sensor of claim 13, wherein the TMR element comprises:
a free layer positioned on the heavy metal layer;
a barrier layer positioned on the free layer; and
a reference layer positioned on the barrier layer.

### Claim 19 (depends on 18)

The sensor of claim 18, wherein the barrier layer includes magnesium oxide (MgO).

### Claim 20 (depends on 18)

The sensor of claim 18, wherein the TMR element comprises a seed layer positioned beneath the heavy metal layer and a capping layer positioned on the reference layer.

### Claim 21 (depends on 4)

The sensor of claim 4, wherein the conductive material layer includes one or more coils.

### Claim 22

A tunnel magnetoresistance (TMR) element comprising:
a heavy metal layer;
a free layer positioned on the heavy metal layer;
a barrier layer positioned on the free layer; and
a reference layer positioned on the barrier layer,
wherein the heavy metal layer is configured to generate a transversal spin current in the TMR element in response to a current flowing through the heavy metal layer, and wherein the transversal spin current is proportional to the current flowing through the heavy metal layer, and the transversal spin current causes a resistance of the TMR element to change.

### Claim 23 (depends on 22)

The TMR element of claim 22, further comprising:
a seed layer positioned beneath the heavy metal layer; and
a capping layer positioned on the reference layer.

### Claim 24 (depends on 22)

The TMR element of claim 22, wherein the barrier layer includes magnesium oxide (MgO).

### Claim 25 (depends on 22)

The TMR element of claim 22, wherein the change of resistance is indicative of a value of the current flowing through the heavy metal layer.