# US 2021/0241809 A1 · Assisted write method for magnetic random access memory

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- Number: US 2021/0241809 A1
- Document ID: US20210241809A1
- Status: Published application
- Kind: A1
- Application number: 17/170,633
- Filed: 2021-02-08
- Published: 2021-08-05
- Earliest claimed: 2018-08-17
- Assignees: Taiwan Semiconductor Manufacturing Company, Ltd.
- Applicants: Taiwan Semiconductor Manufacturing Co., Ltd.
- Inventors: Ji-Feng YING; Jhong-Sheng WANG; Duen-Huei HOU
- Web page: https://patentgrep.com/patent/US20210241809A1

## CPC

- G11C 11/1675: {Writing or programming circuits or methods}
- 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 11/1693: {Timing circuits or methods}
- H01F 10/3254: {the spacer being semiconducting or insulating, e.g. for spin tunnel junction [STJ]}
- H10N 50/01: Manufacture or treatment
- H10N 50/80: Constructional details
- H10P 74/207: {Electrical properties, e.g. testing or measuring of resistance, deep levels or capacitance-voltage characteristics}
- G11C 11/1655: {Bit-line or column circuits}
- G11C 11/1657: {Word-line or row circuits}
- H01F 10/3286: {Spin-exchange coupled multilayers having at least one layer with perpendicular magnetic anisotropy}
- 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}
- 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
- H10P: GENERIC PROCESSES OR APPARATUS FOR THE MANUFACTURE OR TREATMENT OF DEVICES COVERED BY CLASS H10

## Abstract

A method of writing to a magnetic random access memory cell includes applying an alternating current signal to the magnetic random access memory cell having a first magnetic orientation, and applying a direct current pulse to the magnetic random access memory cell to change the magnetic orientation of the magnetic random access memory cell from the first magnetic orientation to a second magnetic orientation. The first magnetic orientation and the second magnetic orientation are different.

## Claims

### Claim 1

(canceled)

### Claim 2

A method of manufacturing a semiconductor device, comprising:
forming a magnetic random access memory cell; and
writing to the magnetic random access memory cell, wherein the writing to the magnetic random access memory cell, comprises:
applying a first alternating current signal to one of a word line or source line of the magnetic random access memory cell,
wherein a first frequency of the first alternating current signal is below a frequency threshold value for causing precession of a free layer of the magnetic random access memory cell;
applying a second alternating current signal to another of the word line or source line of the magnetic random access memory cell,
wherein a second frequency of the second alternating current signal is below the frequency threshold value for causing precession of the free layer of the magnetic random access memory cell, and
a combined frequency of the first frequency and the second frequency is greater than a threshold value for causing precession of the free layer of the magnetic random access memory cell; and
applying a direct current pulse to the magnetic random access memory cell while applying the first alternating current signal and the second alternating current signal to the magnetic random access memory cell thereby changing a magnetic orientation of the magnetic random access memory cell.

### Claim 3 (depends on 2)

The method according to claim 2, wherein the combined frequency of the first and second alternating current signals ranges from 1 GHz to 100 GHz.

### Claim 4 (depends on 2)

The method according to claim 2, wherein a combined voltage peak amplitude of the first and second alternating current signals ranges from 0.1 V to 1 V.

### Claim 5 (depends on 2)

The method according to claim 2, wherein the direct current pulse is a rectangular pulse having a pulse length of 5 nsec to 250 nsec.

### Claim 6 (depends on 2)

The method according to claim 2, wherein a voltage peak amplitude of the direct current pulse ranges from 0.3 V to 3 V.

### Claim 7 (depends on 2)

The method according to claim 2, wherein the forming a magnetic random access memory cell comprises:
forming a first pinned magnetic layer over a first electrode layer;
forming an anti-ferromagnetic layer over the first pinned magnetic layer;
forming a second pinned magnetic layer over the anti-ferromagnetic layer;
forming a tunneling barrier layer over the second pinned magnetic layer;
forming a free magnetic layer over the tunneling barrier layer; and
forming a second electrode layer over the free magnetic layer.

### Claim 8 (depends on 7)

The method according to claim 7, further comprising forming a seed layer over the first electrode layer before forming the first pinned magnetic layer.

### Claim 9 (depends on 7)

The method according to claim 7, further comprising forming a capping layer over the free magnetic layer and a diffusion barrier layer over the capping layer before forming the second electrode layer.

### Claim 10 (depends on 7)

The method according to claim 7, wherein the forming the second pinned magnetic layer comprises:
forming a first layer including cobalt over the anti-ferromagnetic layer;
forming a second layer including a multilayer structure of alternating layers of cobalt and platinum over the first layer;
forming a third layer including Ta, Mo, Co, Pt, Ir, or Ni over the second layer; and
forming a fourth layer including CoFeB, CoPd, or CoFe over the third layer.

### Claim 11 (depends on 7)

The method according to claim 7, wherein the forming the magnetic free layer comprises:
forming a first layer including CoFeB, CoPd, or CoFe over the tunneling barrier layer;
forming a second layer including Ta, Mo, Co, Pt, Ir, or Ni over the first layer; and
forming a third layer including CoFeB, CoPd, or CoFe over the second layer.

### Claim 12

A circuit for writing to an array of magnetic random access memory cells, comprising:
a driver configured to apply a direct current pulse to a random access memory cell;
a first alternating current source f1 configured to apply an alternating current signal to one of a word line or source line of a magnetic random access memory cell in the array; and
a second alternating current source f2 configured to apply a second alternating current signal to another of the word line or source line of the magnetic random access memory cell.

### Claim 13 (depends on 12)

The circuit of claim 12, wherein the driver is a pulse generator.

### Claim 14 (depends on 13)

The circuit of claim 13, wherein the pulse generator is a rectangular pulse generator.

### Claim 15 (depends on 13)

The circuit of claim 13, wherein the pulse generator is configured to provide direct current pulses have a voltage peak amplitude ranging from 0.3 V to 3 V.

### Claim 16 (depends on 12)

The circuit of claim 12, wherein the first alternating current source and the second alternating current source are configured to provide a combined current signal having a frequency of 1 GHz to 100 GHz.

### Claim 17

A method of writing to a magnetic random access memory cell, comprising:
applying an alternating current signal to the magnetic random access memory cell having a first magnetic orientation by sweeping through a range of alternating current frequencies or peak voltage amplitudes of the alternating current signal;
applying direct current pulses to the magnetic random access memory cell by sweeping through a range of peak voltage amplitudes of the direct current pulses; and
changing the magnetic orientation of the magnetic random access memory cell from the first magnetic orientation to a second magnetic orientation,

### Claim 18 (depends on 17)

The method according to claim 17, wherein the first magnetic orientation and the second magnetic orientation are different.

### Claim 19 (depends on 17)

The method according to claim 17, wherein the alternating current signal is superimposed over the direct current pulses.

### Claim 20 (depends on 17)

The method according to claim 17, wherein the range of alternating current frequencies ranges from 1 GHz to 100 GHz.

### Claim 21 (depends on 17)

The method according to claim 17, wherein the range of voltage peak amplitudes of the alternating current signal ranges from 0.1 V to 1 V.