Methods for wordline separation in 3D-NAND devices

Patent metadata

Field	Value
Publication number	US-10354916-B2
Application number	US-201815986189-A
Country	US
Kind code	B2
Filing date	May 22, 2018
Priority date	May 31, 2017
Publication date	Jul 16, 2019
Grant date	Jul 16, 2019

Abstract

Methods of wordline separation in semiconductor devices (e.g., 3D-NAND) are described. A metal film is deposited in the wordlines and on the surface of a stack of spaced oxide layers. The metal film is removed by high temperature oxidation and etching of the oxide or low temperature atomic layer etching by oxidizing the surface and etching the oxide in a monolayer fashion. After removal of the metal overburden, the wordlines are filled with the metal film.

First claim

What is claimed is:

1. A method of processing a substrate, the method comprising:
providing a substrate having a stack of spaced oxide layers with gaps between the oxide layers, the stack having a top and sides, each gap can form a wordline;
depositing a metal on the stack so that the metal fills the gaps and covers the top and sides of the stack with a thickness of metal overburden;
oxidizing the metal to a depth about the thickness of the overburden to form a metal oxide on the top and sides of the stack and leaving the metal in the gaps as wordlines; and
etching the metal oxide from the top and sides of the stack leaving the metal in the wordlines.

2. The method of claim 1 , wherein the metal comprises tungsten and the metal oxide comprises tungsten oxide.

3. The method of claim 1 , wherein the metal consists essentially of tungsten.

4. The method of claim 1 , further comprising forming a barrier layer on the oxide layers and the metal is deposited on the barrier layer.

5. The method of claim 4 , wherein the barrier layer comprises TiN with a thickness in the range of about 20 Å to about 50 Å.

6. The method of claim 1 , wherein there are greater than 50 wordlines.

7. The method of claim 1 , wherein after etching the metal oxide, the metal overburden is removed and the metal in the gaps forming wordlines is substantially even with the sides of the stack.

8. The method of claim 1 , wherein the oxidation and etching occur at a temperature greater than or equal to about 400° C.

9. The method of claim 1 , wherein etching the metal oxide comprises exposing the metal oxide to a metal halide etchant.

10. A method of processing a substrate, the method comprising:
providing a substrate having a stack of spaced oxide layers with gaps between the oxide layers, the stack having a top and sides, each gap can form a wordline;
depositing a metal on the stack so that the metal fills the gaps and covers the top and sides of the stack with a thickness of metal overburden; and
repeatedly oxidizing a surface of the metal to form a metal oxide and etching the metal oxide from the stack until the metal overburden is removed, leaving the metal in the gaps as wordlines.

11. The method of claim 10 , wherein the metal comprises tungsten and the metal oxide comprises tungsten oxide.

12. The method of claim 10 , wherein the metal consists essentially of tungsten.

13. The method of claim 10 , further comprising forming a barrier layer on the spaced oxide layers and the metal is deposited on the barrier layer.

14. The method of claim 13 , wherein the barrier layer comprises TiN with a thickness in the range of about 20 Å to about 50 Å.

15. The method of claim 10 , wherein there are greater than 50 wordlines.

16. The method of claim 10 , wherein after etching, the metal overburden is removed and the metal in the wordlines is substantially even with the sides of the stack.

17. The method of claim 10 , wherein the oxidation and etching occur at a temperature less than or equal to about 400° C.

18. The method of claim 10 , wherein etching the metal oxide comprises exposing the metal oxide to a metal halide etchant.

19. The method of claim 10 , wherein oxidizing the surface of the metal comprises exposing the metal to O 2 .

20. A method of processing a substrate, the method comprising:
providing a substrate having a stack of spaced oxide layers with gaps between the oxide layers, the stack having a top and sides, each gap can form a wordline;
optionally forming a barrier layer on the spaced oxide layers, the barrier layer comprising TiN with a thickness in the range of about 20 Å to about 50 Å;
depositing tungsten on the stack so that the tungsten fills the gaps and covers the top and sides of the stack with a thickness of tungsten overburden; and
repeatedly oxidizing a surface of the tungsten to form a tungsten oxide and etching the tungsten oxide from the stack until the tungsten overburden is removed, leaving the tungsten in the gaps substantially even with the sides of the stack, oxidizing the surface comprising exposure to O 2 and etching the tungsten oxide comprising exposure to one or more of WCl 5 or WCl 6 ,
wherein depositing the tungsten, oxidizing the tungsten and etching the tungsten oxide occur at a temperature less than or equal to about 400° C.

Assignees

• Applied Materials Inc

Inventors

• Chen Yihong
• Duan Ziqing
• Mallick Abhijit Basu
• Chan Kelvin

Classifications

• H10P50/285

  of materials not containing Si, e.g. PZT or Al2O3 · CPC title

• H10P50/266

  by vapour etching only · CPC title

• H10P14/6939

  characterised by the metal · CPC title

• H10P14/6314 Primary

  of a metallic layer · CPC title

• H10P14/418

  the conductive layers comprising transition metals · CPC title