# US 11,444,238 B2 · Scalable heat sink and magnetic shielding for high density MRAM arrays

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- Number: US 11,444,238 B2
- Document ID: US11444238B2
- Status: Granted
- Kind: B2
- Application number: 16/874,002
- Filed: 2020-05-14
- Published: 2021-11-18
- Granted: 2022-09-13
- Earliest claimed: 2020-05-14
- Assignees: International Business Machines Corporation
- Applicants: International Business Machines Corporation
- Inventors: Julien Frougier; Ruilong Xie; Heng Wu; Chen Zhang; Bruce B. Doris
- Web page: https://patentgrep.com/patent/US11444238B2

## CPC

- G11C 11/1695: {Protection circuits or methods}
- H10N 50/80: Constructional details
- 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]}
- 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}
- H01F 41/308: {lift-off processes, e.g. ion milling, for trimming or patterning}
- H01F 41/34: in patterns, e.g. by lithography
- H10B 61/00: Magnetic memory devices, e.g. magnetoresistive RAM [MRAM] devices
- H10N 50/01: Manufacture or treatment
- G11C: STATIC STORES (semiconductor memory devices H10B)
- H10N: ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
- H01F: MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
- H10B: ELECTRONIC MEMORY DEVICES

## Abstract

A magnetic random access memory (MRAM) array includes a plurality of MRAM cells, each of the MRAM cells including a magnetic tunnel junction (MTJ) stack disposed on a bottom metal via connecting the MTJ stack to a bottom conductive contact in a substrate, a plurality of top conductive contacts, each of the top conductive contacts disposed on a respective one of the MTJ stacks, and a plurality of unitary structures configured as a heat sink/magnetic shield disposed on a vertical portions of each of the MRAM cells, including vertical portions of the bottom metal vias, and under a portion of each of the MTJ stacks.

## Claims

### Claim 1

A magnetic random access memory (MRAM) array comprising:
a plurality of MRAM cells, each of the MRAM cells comprising a magnetic tunnel junction (MTJ) stack disposed on a bottom metal via connecting the MTJ stack to a bottom conductive contact in a substrate;
a plurality of top conductive contacts, each of the top conductive contacts disposed on a respective one of the MTJ stacks; and
a plurality of unitary structures configured as a heat sink and magnetic shield disposed on a vertical portions of each of the MRAM cells, including vertical portions of the bottom metal vias, and under a portion of each of the MTJ stacks.

### Claim 2 (depends on 1)

The MRAM array of claim 1, wherein each of the unitary structures wraps entirely around a respective one of the MRAM cells and has a height recessed below a height of a metal hardmask disposed on the MTJ stack and above a top of the MTJ stack.

### Claim 3 (depends on 1)

The MRAM array of claim 1, wherein each of the MRAM cells further comprises a toroidal bottom dielectric spacer in contact with bottom surface of the MTJ stack and formed around a top portion of the bottom metal via.

### Claim 4 (depends on 1)

The MRAM array of claim 1, wherein each of the MRAM cells further comprises a vertical sidewall spacer disposed on the vertical portions of the MRAM cell and extending below a bottom of a dielectric spacer formed on a lower surface of the MTJ stack.

### Claim 5 (depends on 1)

The MRAM array of claim 1, wherein each of the unitary structures comprises an air-gap around the bottom metal via.

### Claim 6 (depends on 1)

The MRAM array of claim 1, further comprising a top heat sink/magnetic shield formed on over the MTJ stack.

### Claim 7 (depends on 1)

The MRAM array of claim 1, wherein each of the unitary structures is isolated from the MTJ stack by a vertical sidewall spacer and a toroidal bottom dielectric spacer.

### Claim 8 (depends on 1)

The MRAM array of claim 1, further comprising a first conformal dielectric liner disposed on the MRAM cells, exposed portions of the bottom metal vias, the bottom conductive contacts and the substrate, wherein the first conformal dielectric liner is further disposed under the unitary structures.

### Claim 9 (depends on 8)

The MRAM array of claim 8, further comprising a second magnetic shield disposed on a portion of the conformal unitary structures.

### Claim 10 (depends on 9)

The MRAM array of claim 9, wherein the unitary structures exhibit a pinch-off below the MTJ stack.

### Claim 11 (depends on 8)

The MRAM array of claim 8, further comprising a second conformal dielectric liner disposed on the unitary structures and exposed portions of the first conformal dielectric liner.

### Claim 12 (depends on 11)

The MRAM array of claim 11, further comprising a second magnetic shield disposed on a portion of the second conformal dielectric liner.