Pre-treatment method to improve selectivity in a selective deposition process

• US 10,643,889 B2
• Filed: 08/06/2018
• Issued: 05/05/2020
• Est. Priority Date: 08/06/2018
• Status: Active Grant

• Current Assignee: Lam Research Corporation
• Original Assignee: Lam Research (Shanghai) Co., Ltd. (Lam Research Corporation)
• Inventors: Hausmann, Dennis, Mohimi, Elham, Zhang, Pengyi, Lemaire, Paul C., Sharma, Kashish, Fox, Alexander R., Shankar, Nagraj, Reddy, Kapu Sirish, Smith, David Charles
• Primary Examiner(s): Cao, Phat X
• Assistant Examiner(s): Barzykin, Victor V
• Application Number:
  US16/056,260
• Publication Number:
  US 20200043776A1
• Time in Patent Office: 638 Days
• CPC Class Codes: H01L 21/02074 the processing being a planarization of conductive layers
• CPC Class Codes: H01L 21/02178 the material containing aluminium, e.g. Al2O3
• CPC Class Codes: H01L 21/0228 deposition by cyclic CVD, e.g. ALD, ALE, pulsed CVD
• CPC Class Codes: H01L 21/02614 Transformation of metal, e.g. oxidation, nitridation
• CPC Class Codes: H01L 21/32 using masks
• CPC Class Codes: H01L 21/321 After treatment
• CPC Class Codes: H01L 21/3212 by chemical mechanical polishing [CMP]
• CPC Class Codes: H01L 21/76829 characterised by the formation of thin functional dielectric layers, e.g. dielectric etch-stop, barrier, capping or liner layers
• CPC Class Codes: H01L 21/76879 by selective deposition of conductive material in the vias, e.g. selective C.V.D. on semiconductor material, plating plating on semiconductors in general H01L21/288
• CPC Class Codes: H01L 21/76883 Post-treatment or after-treatment of the conductive material

Abstract

A method of improving selectivity of a metal in a selective deposition process. A pre-treatment process for the metal modifies the metal surface, and includes first reducing the metal to remove organic contamination from the metal followed by oxidation of the metal to allow a monolayer of a metal oxide to grow on the surface. This modification of the metal allows inhibitor molecules to adsorb on the metal oxide monolayer to improve selectivity.

Claims

1. A method for improving the selectivity of metal, the method comprising:

providing a substrate in a semiconductor processing chamber, the substrate having metal lines formed in a dielectric layer;

reducing the metal from a metal oxide to metal by removing organic contamination from the metal; and

oxidizing the metal by flowing O₂ or O₂ plasma into the semiconductor processing chamber and allowing a monolayer of metal oxide to thermally grow on a surface of the metal after reducing the metal.

2. The method as recited in claim 1, further comprising depositing inhibitor molecules that are selective only to the metal and allowing the inhibitor molecules to adsorb on the monolayer of metal oxide after allowing the monolayer to grow.

3. The method as recited in claim 1, wherein the metal is deposited by an electrofill process.

4. The method as recited in claim 3, wherein the metal is chemically mechanically polished after it is deposited.

5. The method as recited in claim 1, wherein the metal is selected from the group consisting of copper, cobalt, and tungsten.

6. The method as recited in claim 1, wherein the dielectric layer comprises silicon oxide.

7. The method as recited in claim 1, wherein reducing comprises flowing hydrogen plasma, a plasma mixture of ammonia and nitrogen, ammonia plasma, a non-thermal diborane plasma, citric acid, or acetic acid into the chamber.

8. The method as recited in claim 1, wherein oxidizing comprises flowing an oxygen plasma, oxygen, ozone, or hydrogen peroxide into the chamber.

9. The method as recited in claim 2, wherein the inhibitor molecules comprise a thiol or phosphonic acid.

10. A method for improving the selectivity of copper deposited by an electrofill process, the method comprising:

providing a substrate in a semiconductor processing chamber, the substrate having copper lines formed in a dielectric layer;

reducing the copper from a copper oxide to copper by removing organic contamination from the copper;

oxidizing the copper by flowing O₂ or O₂ plasma into the semiconductor processing chamber and allowing a monolayer of copper oxide to thermally grow on a surface of the copper after reducing the copper; and

depositing inhibitor molecules that are selective only to the copper and allowing the inhibitor molecules to adsorb on the monolayer of copper oxide after allowing the monolayer to grow.

11. The method as recited in claim 10, wherein the copper is chemically mechanically polished after the electrofill process and before reducing the copper.

12. The method as recited in claim 10, wherein the dielectric layer comprises silicon oxide.

13. The method as recited in claim 10, wherein reducing comprises flowing hydrogen plasma, a plasma mixture of ammonia and nitrogen, ammonia plasma, a non-thermal diborane plasma, citric acid, or acetic acid into the chamber.

14. The method as recited in claim 10, wherein oxidizing comprises flowing an oxygen plasma, oxygen, ozone, or hydrogen peroxide into the chamber.

15. The method as recited in claim 10, wherein the inhibitor molecules comprise a thiol.

16. A method for improving the selectively depositing an etch stop layer, the method comprising:

providing a substrate in a semiconductor processing chamber, the substrate having a dielectric on its surface;

depositing copper onto the surface of the substrate by an electrofill process;

chemically mechanically polishing the copper deposited by the electrofill process;

flowing a plasma mixture of ammonia and nitrogen into the chamber to reduce the copper from a copper oxide to copper by removing organic contamination from the copper after chemically mechanically polishing the copper;

flowing an oxygen plasma or oxygen into the chamber to oxidize the copper and allowing a monolayer of copper oxide to grow on a surface of the copper after reducing the copper;

depositing thiol molecules that are selective only to the copper and allowing the thiol molecules to adsorb on the monolayer of copper oxide after allowing the monolayer to grow; and

selectively depositing an etch stop layer over the dielectric layer.

17. The method as recited in claim 16, wherein the dielectric comprises silicon oxide.

18. The method as recited in claim 16, wherein etch stop layer comprises aluminum oxide.

19. The method as recited in claim 16, wherein the etch stop layer is deposited by a thermal atomic layer deposition process.