Ultra low silicon loss high dose implant strip

Patent metadata

Field	Value
Publication number	US-9564344-B2
Application number	US-201514721977-A
Country	US
Kind code	B2
Filing date	May 26, 2015
Priority date	Dec 11, 2009
Publication date	Feb 7, 2017
Grant date	Feb 7, 2017

Abstract

Improved methods for stripping photoresist and removing ion implant related residues from a work piece surface are provided. According to various embodiments, plasma is generated using elemental hydrogen, a fluorine-containing gas and a protectant gas. The plasma-activated gases reacts with the high-dose implant resist, removing both the crust and bulk resist layers, while simultaneously protecting exposed portions of the work piece surface. The work piece surface is substantially residue free with low silicon loss.

First claim

What is claimed is:

1. A method of removing a resist from a work piece surface in a reaction chamber, the method comprising:
forming a first plasma from a process gas mixture comprising molecular hydrogen, a non-carbon-containing fluorine-containing gas and a protectant compound, wherein said non-carbon-containing fluorine-containing gas and said protectant compound are provided in a first volumetric flow ratio, wherein the volumetric ratio of the molecular hydrogen to the non-carbon-containing fluorine-containing gas is at least 10:1;
exposing the work piece surface to the first plasma to thereby remove a first portion of the resist from the work piece surface;
changing the volumetric flow ratio of said non-carbon-containing fluorine-containing gas and said protectant compound to form a second plasma; and
exposing the work piece surface to the second plasma to thereby remove a second portion of the resist from the work piece surface.

2. The method of claim 1 , wherein the protectant compound is a nitrogen-containing compound.

3. The method of claim 1 , wherein the protectant compound is a fluorocarbon protectant compound.

4. The method of claim 3 , wherein the fluorocarbon protectant compound is one of CF 4 , C 2 F 6 , CHF 3 , CH 2 F 2 , C 3 F 8 .

5. The method of claim 1 , wherein the non-carbon-containing fluorine-containing gas is one of NF 3 , F 2 , HF or SF 6 .

6. The method of claim 5 , wherein the non-carbon-containing fluorine-containing gas is NF 3 .

7. The method of claim 1 , wherein the resist removed from the work piece surface comprises a high-dose implanted resist wherein the first or section portion of the resist includes crosslinked polymer chains.

8. The method of claim 7 , wherein the work piece is substantially residue free of the high-dose implanted resist after removal and wherein less than about 2 angstroms silicon is lost from a silicon surface of the work piece.

9. The method of claim 7 , wherein the work piece is substantially residue free of the high-dose implanted resist after removal and wherein less than about 1 angstrom silicon is lost from a silicon surface of the work piece.

10. The method of claim 1 , wherein the first volumetric flow ratio of said non-carbon-containing fluorine-containing gas and said protectant compound is between about 1:20-1:5 and changing the volumetric flow ratio comprises changing the volumetric flow ratio to between about 1:4-1:2.

11. The method of claim 1 , wherein the first volumetric flow ratio of the non-carbon-containing fluorine-containing gas and said protectant compound is between about 1:20-1:5.

12. The method of claim 1 , wherein changing the volumetric flow ratio of said non-carbon-containing fluorine-containing gas and said protectant compound to form a second plasma comprises shutting off a flow of the protectant compound.

13. The method of claim 1 , wherein the process gas mixture further comprises carbon dioxide.

14. The method of claim 1 , wherein the resist is an ion-implanted resist including a crust portion and a bulk portion, wherein the crust portion is denser than the bulk portion, wherein the crust portion includes carbon and wherein at least some of the crust portion is removed by the first plasma.

15. A method of removing resist from a work piece surface in a reaction chamber, the method comprising:
forming a first plasma from a process gas mixture comprising molecular hydrogen, non-carbon-containing fluorine-containing gas and a protectant compound, wherein the volumetric ratio of the molecular hydrogen to the non-carbon-containing fluorine gas is at least 10:1; and
exposing the work piece surface to the first plasma to thereby remove a first portion of resist from the work piece surface and simultaneously form a protective layer on a silicon-containing surface of the work piece, wherein the resist is an ion-implanted resist including a crust portion and a bulk portion, wherein the crust portion is denser than the bulk portion, wherein the crust includes carbon and wherein at least some of the crust is removed by the first plasma.

16. The method of claim 15 , wherein the protectant compound is a nitrogen-containing compound.

17. The method of claim 15 , wherein the protectant compound is a fluorocarbon protectant compound.

18. The method of claim 15 , wherein the non-carbon-containing fluorine-containing gas is one of NF 3 , F 2 , HF or SF 6 .

19. The method of claim 15 , wherein the protectant compound is CF 4 and the non-carbon-containing fluorine-containing gas is NF 3 .

20. The method of claim 15 , wherein the process gas mixture further comprises carbon dioxide.

21. A method of removing high-dose implanted resist from a work piece surface in a reaction chamber, the method comprising:
removing a first portion of the high-dose implanted resist comprising:
introducing a first gas comprising molecular hydrogen, a weak oxidizing agent, a non-carbon-containing fluorine containing gas and a protectant gas into a plasma source, wherein the volumetric ratio of the molecular hydrogen to the non-carbon-containing fluorine gas is at least 10:1;
generating a first plasma from the first gas introduced into the plasma source; and
exposing the work piece to a first plasma to remove a first portion of the high-dose implanted resist;

and removing a second portion of the high-dose implanted resist by:
introducing a second gas comprising molecular hydrogen, a weak oxidizing agent, a non-carbon-containing fluorine containing gas and essentially no protectant gas into a plasma source;
generating a second plasma from the second gas introduced into the plasma source; and

exposing the work piece to the second plasma to remove a second portion of the high-dose implanted resist wherein the first or section portion of the high-dose implanted resist includes crosslinked polymer chains.

Assignees

• Novellus Systems Inc

Inventors

• Cheung David
• Fang Haoquan
• Kuo Jack
• Kalinovski Ilia
• Li Zhao
• Yao Guhua
• Guha Anirban
• Ostrowski Kirk J

Classifications

• H10P50/283

  by chemical means · CPC title

• H10P50/268

  of silicon-containing layers · CPC title

• H10P50/267

  using plasmas · CPC title

• H10P50/73

  using masks for insulating materials · CPC title

• H10P50/71

  using masks for conductive or resistive materials · CPC title