# US 10,374,144 B2 · Dry plasma etch method to pattern MRAM stack

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- Number: US 10,374,144 B2
- Document ID: US10374144B2
- Status: Granted
- Kind: B2
- Application number: 15/719,497
- Filed: 2017-09-28
- Published: 2018-01-18
- Granted: 2019-08-06
- Earliest claimed: 2015-04-20
- Assignees: Lam Research Corporation
- Applicants: Lam Research Corporation
- Inventors: Samantha Tan; Taeseung Kim; Wenbing Yang; Jeffrey Marks; Thorsten Lill
- Web page: https://patentgrep.com/patent/US10374144B2

## CPC

- H10N 35/01: Manufacture or treatment
- C23F 1/12: Gaseous compositions
- C23F 4/00: Processes for removing metallic material from surfaces, not provided for in group C23F1/00 or C23F3/00
- H01J 37/32082: {Radio frequency generated discharge (H01J37/32357, H01J37/32366, H01J37/32394 and H01J37/32403 take precedence)}
- H01J 37/32422: {Arrangement for selecting ions or species in the plasma}
- H01J 37/32651: {Shields, e.g. dark space shields, Faraday shields}
- H10B 61/00: Magnetic memory devices, e.g. magnetoresistive RAM [MRAM] devices
- H10N 50/01: Manufacture or treatment
- H10N: ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
- C23F: NON-MECHANICAL REMOVAL OF METALLIC MATERIAL FROM SURFACE (working metal by laser beams B23K26/00; desurfacing by applying flames B23K7/00; working of metal by electro-erosion B23H; producing decorative effects by removing surface material, e.g. by engraving, by etching, B44C1/22; electrolytic etching or polishing C25F); INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL; MULTI-STEP PROCESSES FOR SURFACE TREATMENT OF METALLIC MATERIAL INVOLVING AT LEAST ONE PROCESS PROVIDED FOR IN CLASS C23 AND AT LEAST ONE PROCESS COVERED BY SUBCLASS C21D OR C22F OR CLASS C25
- H01J: ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS (spark-gaps H01T; electric arc lamps H05B31/00; particle accelerators H05H)
- H10B: ELECTRONIC MEMORY DEVICES

## Abstract

Methods of etching metal by depositing a material reactive with a metal to be etched and a halogen to form a volatile species and exposing the substrate to a halogen-containing gas and activation gas to etch the substrate are provided. Deposited materials may include silicon, germanium, titanium, carbon, tin, and combinations thereof. Methods are suitable for fabricating MRAM structures and may involve integrating ALD and ALE processes without breaking vacuum.

## Claims

### Claim 1

A method comprising:
(a) providing a substrate comprising two or more metal layers, a free layer, a dielectric barrier layer, and a fixed layer, wherein the dielectric barrier layer is between the free layer and the fixed layer, and wherein the free layer, the dielectric barrier layer, and the fixed layer are between the two or more metal layers,
(b) exposing the substrate to a silicon-containing gas and a reducing agent to deposit a silicon-containing material on the substrate,
(c) exposing the substrate to a halogen-containing gas for a duration sufficient to substantially saturate a surface of the substrate, and
(d) exposing the substrate to an activation gas to etch the substrate.

### Claim 2 (depends on 1)

The method of claim 1, further comprising:
repeating (b) after substantially all of the free layer is etched and before the dielectric barrier layer is exposed,
etching the dielectric barrier layer with a halogen-free chemistry, and
repeating (c) and (d) to etch the substrate after the dielectric barrier layer is etched.

### Claim 3 (depends on 1)

The method of claim 1, wherein the halogen-containing gas is selected from the group consisting of Cl2, BCl3, BBr3, BI3, F2, BF3, Br2, I2 and combinations thereof.

### Claim 4 (depends on 1)

The method of claim 1, wherein (c) and (d) are repeated in two or more cycles.

### Claim 5 (depends on 1)

The method of claim 1, wherein (a)-(d) are performed without breaking vacuum.

### Claim 6 (depends on 1)

The method of claim 1, wherein (b) mitigates re-deposition of metal-containing byproducts.

### Claim 7 (depends on 1)

The method of claim 1, wherein the silicon-containing material is reactive with both the halogen-containing gas and a metal material of at least one of the two or more metal layers of the substrate selected from the group consisting of Period IV transition metals, Period V transition metals, Period VI transition metals, and combinations thereof.

### Claim 8 (depends on 7)

The method of claim 7, wherein the metal material of the at least one of the two or more metal layers selected from the group consisting of Period IV transition metals, Period V transition metals, Period VI transition metals, and combinations thereof and the dielectric barrier layer are adjacent layers on the substrate.

### Claim 9 (depends on 1)

The method of claim 1, wherein the silicon-containing material is selected from the group consisting of is silicon nitride, silicon oxide and silicon.

### Claim 10 (depends on 1)

The method of claim 1, wherein the silicon-containing material is deposited by a self-limiting reaction.

### Claim 11 (depends on 1)

The method of claim 1, wherein the silicon-containing material remains on sidewalls of features of the substrate during (d).

### Claim 12 (depends on 1)

The method of claim 1, wherein the silicon-containing material protects at least one of the two or more metal layers of the substrate during (d).

### Claim 13 (depends on 1)

The method of claim 1, further comprising applying a bias during (d) at a power less than about 100 Vb.

### Claim 14 (depends on 1)

The method of claim 1, wherein (d) comprises activating the activation gas using one of plasma, ion-beam etching, and thermal activation.

### Claim 15

A method comprising:
(a) providing a substrate comprising two or more metal layers, a free layer, a dielectric barrier layer, and a fixed layer, wherein the dielectric barrier layer is between the free layer and the fixed layer, and the free layer, the dielectric barrier layer, and the fixed layer are between the two or more metal layers,
(b) exposing the substrate to a precursor gas and a reducing agent to deposit a material selected from the group consisting of silicon-containing material, titanium-containing material, germanium-containing material, tin-containing material, carbon-containing material, and combinations thereof on the substrate,
(c) exposing the substrate to a halogen-containing gas for a duration sufficient to substantially saturate a surface of the substrate, and
(d) exposing the substrate to an activation gas to etch the substrate.

### Claim 16 (depends on 15)

The method of claim 15, wherein the material is the titanium-containing material and is selected from the group consisting of titanium oxide or titanium nitride.