Gradient Protection Layer in MTJ Manufacturing

• US 20200136026A1
• Filed: 10/25/2018
• Published: 04/30/2020
• Est. Priority Date: 10/25/2018
• Status: Active Grant

• Current Assignee: Taiwan Semiconductor Manufacturing Company Limited
• Original Assignee: Taiwan Semiconductor Manufacturing Company Limited
• Inventors: Peng, Tai-Yen, Chen, Yu-Shu, Yang, Sin-Yi, Wang, Chen-Jung, Huang, Chien Chung, Lin, Han-Ting, Shieh, Jyu-Horng, Fu, Qiang
• Granted Patent: US 10,868,239 B2
• Time in Patent Office: Days
• CPC Class Codes: H10N 50/01 Manufacture or treatment
• CPC Class Codes: H10N 50/10 Magnetoresistive devices
• CPC Class Codes: H10N 50/80 Constructional details

Abstract

A method includes forming Magnetic Tunnel Junction (MTJ) stack layers, which includes depositing a bottom electrode layer; depositing a bottom magnetic electrode layer over the bottom electrode layer; depositing a tunnel barrier layer over the bottom magnetic electrode layer; depositing a top magnetic electrode layer over the tunnel barrier layer; and depositing a top electrode layer over the top magnetic electrode layer. The method further includes patterning the MTJ stack layers to form a MTJ; and performing a passivation process on a sidewall of the MTJ to form a protection layer. The passivation process includes reacting sidewall surface portions of the MTJ with a process gas comprising elements selected from the group consisting of oxygen, nitrogen, carbon, and combinations thereof.

Claims

1. A method comprising:

forming Magnetic Tunnel Junction (MTJ) stack layers comprising;

depositing a bottom electrode layer;

depositing a bottom magnetic electrode layer over the bottom electrode layer;

depositing a tunnel barrier layer over the bottom magnetic electrode layer;

depositing a top magnetic electrode layer over the tunnel barrier layer; and

depositing a top electrode layer over the top magnetic electrode layer;

patterning the MTJ stack layers to form an MTJ; and

performing a first passivation process on a sidewall of the MTJ to form a first protection layer, wherein the first passivation process comprises reacting sidewall surface portions of the MTJ with a process gas comprising elements selected from the group consisting of oxygen, nitrogen, carbon, and combinations thereof.

2. The method of claim 1, wherein the patterning the MTJ stack layers comprises:

etching the top electrode layer, the top magnetic electrode layer, and the tunnel barrier layer, wherein the first passivation process is performed after the top electrode layer, the top magnetic electrode layer, and the tunnel barrier layer are etched, and before at least a majority of the bottom magnetic electrode layer is etched.

3. The method of claim 2 further comprising:

after the first passivation process, etching the bottom magnetic electrode layer; and

performing a second passivation process to form a second protection layer, wherein the second protection layer extends on sidewalls of a remaining portion of the bottom magnetic electrode layer.

4. The method of claim 3 further comprising:

after the second passivation process, etching the bottom electrode layer; and

performing a third passivation process to form a third protection layer, wherein the third protection layer extends on sidewalls of a remaining portion of the bottom electrode layer.

5. The method of claim 1, wherein the patterning the MTJ stack layers is performed in an etching chamber, and the first passivation process is performed in the etching chamber.

6. The method of claim 5, wherein the patterning the MTJ stack layers and the first passivation process are in-situ performed without vacuum break therebetween.

7. The method of claim 1, wherein the first passivation process comprises tilted treatments using the process gas, with the tilted treatments tilted in opposite directions.

8. The method of claim 1, wherein the process gas is selected from the group consisting of O₂, N₂, CO, CO₂, CH₃OH, and combinations thereof, with plasma turned on in the first passivation process, and a bias power applied.

9. The method of claim 1 further comprising:

depositing a blanket dielectric layer, wherein the blanket dielectric layer comprises portions on opposite sides of the first protection layer; and

depositing a gap-filling dielectric material on the blanket dielectric layer.

10. The method of claim 1 further comprising:

depositing a gap-filling dielectric material, with no blanket dielectric being formed using deposition between the gap-filling dielectric material and the MTJ.

11. A method comprising:

etching a top electrode layer to form a top electrode;

etching a top magnetic electrode layer underlying the top electrode layer to form a top magnetic electrode;

etching a tunnel barrier layer underlying the top magnetic electrode layer to form a tunnel barrier;

performing a first passivation process on sidewalls of the top electrode, the top magnetic electrode, and the tunnel barrier to form a first protection layer;

etching a bottom magnetic electrode layer underlying the tunnel barrier to form a bottom magnetic electrode; and

performing a second passivation process on sidewalls of the bottom magnetic electrode to form a second protection layer, wherein each of the first passivation process and the second passivation process comprises a process selected from the group consisting of an oxidation process, a carbonization process, a nitridation process, and combinations thereof.

12. The method of claim 11, wherein the first passivation process comprises oxidizing surface portions the top electrode, the top magnetic electrode, and the tunnel barrier to form a metal oxide.

13. The method of claim 11, wherein the first passivation process comprises nitriding surface portions the top electrode, the top magnetic electrode, and the tunnel barrier to form a metal nitride.

14. The method of claim 11, wherein the first passivation process comprises carbonating surface portions the top electrode, the top magnetic electrode, and the tunnel barrier to form a metal carbide.

15. The method of claim 11 further comprising:

etching a bottom electrode layer underlying the bottom magnetic electrode to form a bottom electrode; and

performing a third passivation process on sidewalls of the bottom electrode to form a third protection layer.

16. The method of claim 11, wherein when the second passivation process is performed, the first protection layer is exposed.

17-20. -20. (canceled)

21. A method comprising:

depositing a bottom electrode layer;

depositing a bottom magnetic electrode layer over the bottom electrode layer;

forming stacked layers comprising;

a tunnel barrier over the bottom magnetic electrode layer;

a top magnetic electrode over the tunnel barrier; and

a top electrode over the top magnetic electrode; and

performing a first passivation process to from a first protection layer on sidewalls of the stacked layers, wherein the first protection layer comprises a first element selected from the group consisting of oxygen, nitrogen, carbon, and combinations thereof.

22. The method of claim 21, wherein in the first passivation process, an inner portion of the stack layers between the opposing outer portions of the stacked layers is not added with the first element.

23. The method of claim 21 further comprising:

after the first passivation process, etching the bottom magnetic electrode layer; and

performing a second passivation process to form a second protection layer on the first protection layer, wherein the second protection layer comprises a second element selected from the group consisting of oxygen, nitrogen, carbon, and combinations thereof.

24. The method of claim 23 further comprising:

after the second passivation process, etching the bottom electrode layer; and

performing a third passivation process to form a third protection layer on the second protection layer, wherein the third protection layer comprises a third element selected from the group consisting of oxygen, nitrogen, carbon, and combinations thereof.