# US 2017/0287979 A1 · Strain assisted spin torque switching spin transfer torque memory

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- Number: US 2017/0287979 A1
- Document ID: US20170287979A1
- Status: Published application
- Kind: A1
- Application number: 15/508,430
- Filed: 2014-09-25
- Published: 2017-10-05
- Earliest claimed: 2014-09-25
- Assignees: Intel Corporation
- Applicants: Intel Corporation
- Inventors: Sasikanth Manipatruni; Dmitri E. Nikonov; Asif Khan; Raseong KIM; Tahir Ghani; Ian A. Young
- Web page: https://patentgrep.com/patent/US20170287979A1

## CPC

- H10B 61/22: {of the field-effect transistor [FET] type}
- G11C 11/161: {details concerning the memory cell structure, e.g. the layers of the ferromagnetic memory cell}
- G11C 11/1659: {Cell access}
- G11C 11/1675: {Writing or programming circuits or methods}
- H10N 35/85: Magnetostrictive active materials
- H10N 39/00: Integrated devices, or assemblies of multiple devices, comprising at least one piezoelectric, electrostrictive or magnetostrictive element covered by groups H10N30/00 – H10N35/00
- H10N 50/10: Magnetoresistive devices
- H10N 50/80: Constructional details
- H10N 50/85: Materials of the active region
- H10B 53/00: Ferroelectric RAM [FeRAM] devices comprising ferroelectric memory capacitors
- H10B 53/30: characterised by the memory core region
- H10D 1/682: {having dielectrics comprising perovskite structures}
- H10B: ELECTRONIC MEMORY DEVICES
- G11C: STATIC STORES (semiconductor memory devices H10B)
- H10N: ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
- H10D: INORGANIC ELECTRIC SEMICONDUCTOR DEVICES

## Abstract

Described is an apparatus which comprises: a magnetic tunneling junction (MTJ) having a free magnetic layer; a piezoelectric layer; and a conducting strain transfer layer coupled to the free magnetic layer and the piezoelectric layer. Described is a method, which comprises: exciting a piezoelectric layer with a voltage driven capacitive stimulus; and writing to a MTJ coupled to the piezoelectric layer via a strain assist layer. Described is also an apparatus which comprises: a transistor; a conductive strain transfer layer coupled to the transistor; and a MTJ device having a free magnetic layer coupled to the conductive strain transfer layer.

## Claims

### Claim at position 1

1-25. (canceled)

### Claim 26

An apparatus comprising:
a magnetic tunneling junction (MTJ) having a free magnetic layer;
a piezoelectric layer; and
a conducting strain transfer layer coupled to the free magnetic layer and the piezoelectric layer.

### Claim 27 (depends on 26)

The apparatus of claim 26 comprises:
a first electrode coupled to the MTJ;
a second electrode coupled to the conducting strain transfer layer; and
a third electrode coupled to the piezoelectric layer.

### Claim 28 (depends on 27)

The apparatus of claim 27 comprises:
a first bit-line for coupling to the first electrode;
a source line for coupling to the second electrode; and
a second bit-line for coupling to the third electrode.

### Claim 29 (depends on 28)

The apparatus of claim 28, wherein:
the first bit-line is disposed on a fourth metal line layer,
the second bit-line is disposed on the second metal line layer, and
the source line is disposed on the zero metal line layer.

### Claim 30 (depends on 29)

The apparatus of claim 29, wherein the MTJ is formed in a region dedicated for the second metal line layer.

### Claim 31 (depends on 28)

The apparatus of claim 28, wherein:
the first bit-line is disposed on a fourth metal line layer,
the second bit-line is disposed on the sixth metal line layer, and
the source line is disposed on the second metal line layer.

### Claim 32 (depends on 28)

The apparatus of claim 28 comprises:
a first transistor coupled to the source line and the second electrode, the first transistor for coupling the source line to the second electrode according to a voltage potential of a select line.

### Claim 33 (depends on 32)

The apparatus of claim 32 comprises:
a second transistor coupled to the third electrode and the second bit-line, the second transistor for coupling the second bit-line to the third electrode according to a voltage potential of the select line.

### Claim 34 (depends on 26)

The apparatus of claim 26 comprises layers of:
first electrode; anti-ferromagnetic layer; fixed magnet layer; exchange coupling layer; fixed magnet layer; tunnel oxide; free magnetic layer with magneto-striction; conducting strain transfer layer; piezoelectric layer; and second electrode.

### Claim 35 (depends on 26)

The apparatus of claim 26, wherein the MTJ is formed with layers of: IrMn; CoFe; Ru; CoFeB; MgO; and CoFeB.

### Claim 36 (depends on 26)

The apparatus of claim 26, wherein the conducting strain transfer layer is formed with one of: W, Ta, Cu, Nb, or STO, and wherein the free magnetic layer with magneto-striction is formed from one of: CoFeB, FeGa, MnGa, or Terfenol.

### Claim 37 (depends on 26)

The apparatus of claim 26, wherein the piezoelectric layer is a composite layer.

### Claim 38

A system comprising:
a processor;
a magnetic random access memory (MRAM) coupled to the processor, the MRAM having a bit-cell including:
a magnetic tunneling junction (MTJ) having a free magnetic layer;
a piezoelectric layer; and
a conducting strain transfer layer coupled to the free magnetic layer and the piezoelectric layer; and
a wireless interface for allowing the processor to couple to another device.

### Claim 39 (depends on 38)

The system of claim 38, wherein the conducting strain transfer layer is formed with one of: W, Ta, Cu, Nb, or STO, and wherein the free magnetic layer with magneto-striction is formed from one of: CoFeB, FeGa, MnGa, or Terfenol.

### Claim 40

An apparatus comprising:
a transistor;
a conductive strain transfer layer coupled to the transistor; and
a Magnetic Tunnel Junction (MTJ) device having a free magnetic layer coupled to the conductive strain transfer layer.

### Claim 41 (depends on 40)

The apparatus of claim 40, wherein the transistor has a gate terminal coupled to a select line.

### Claim 42 (depends on 40)

The apparatus of claim 40, comprises
a piezoelectric layer coupled to the conductive strain transfer layer.

### Claim 43 (depends on 42)

The apparatus of claim 42 comprises:
a first electrode coupled to the MTJ;
a second electrode coupled to the conductive strain transfer layer; and
a third electrode coupled to the piezoelectric layer.

### Claim 44 (depends on 43)

The apparatus of claim 43, wherein the transistor is coupled to the second electrode, and wherein the transistor is operable to electrically couple the source line to the second electrode according to a voltage potential of the select line.

### Claim 45 (depends on 44)

The apparatus of claim 44 comprises another transistor coupled to the third electrode and the select line.

### Claim 46 (depends on 40)

The apparatus of claim 40, wherein the MTJ comprises layers of: first electrode; anti-ferromagnetic layer; fixed magnet layer; exchange coupling layer; fixed magnet layer; tunnel oxide; free magnetic layer with magneto-striction; conducting strain transfer layer; piezoelectric layer; and second electrode.

### Claim 47 (depends on 40)

The apparatus of claim 40, wherein the MTJ is formed with layers of: IrMn; CoFe; Ru; CoFeB; MgO; and CoFeB.

### Claim 48 (depends on 40)

The apparatus of claim 40, wherein the conductive strain transfer layer is formed with one of: W, Ta, Cu, Nb, or STO, and wherein the free magnetic layer with magneto-striction is formed from one of: CoFeB, FeGa, MnGa, or Terfenol.