Selective oxide etching method for self-aligned multiple patterning

• US 10,658,192 B2
• Filed: 09/04/2018
• Issued: 05/19/2020
• Est. Priority Date: 09/13/2017
• Status: Active Grant

• Current Assignee: Tokyo Electron Limited
• Original Assignee: Tokyo Electron Limited
• Inventors: Sherpa, Sonam D., Ranjan, Alok
• Primary Examiner(s): Mulpuri, Savitri
• Application Number:
  US16/120,554
• Publication Number:
  US 20190080925A1
• Time in Patent Office: 623 Days
• CPC Class Codes: H01L 21/0234 treatment by exposure to a plasma
• CPC Class Codes: H01L 21/0332 characterised by their composition, e.g. multilayer masks, materials
• CPC Class Codes: H01L 21/0337 characterised by the process involved to create the mask, e.g. lift-off masks, sidewalls, or to modify the mask, e.g. pre-treatment, post-treatment
• CPC Class Codes: H01L 21/31116 by dry-etching
• CPC Class Codes: H01L 21/31144 using masks

Abstract

A method of etching is described. The method includes forming a first chemical mixture by plasma-excitation of a first process gas containing an inert gas and at least one additional gas selected from the group consisting of He and H₂, and exposing the first material on the substrate to the first chemical mixture to modify a first region of the first material. Thereafter, the method includes forming a second chemical mixture by plasma-excitation of a second process gas containing an inert gas and an additional gas containing C, H, and F, and exposing the first material on the substrate to the second plasma-excited process gas to selectively etch the first material, which contains silicon oxide, relative to the second material and remove the modified first material from the first region of the substrate.

Claims

1. A method of etching, comprising:

providing a substrate having a first material containing silicon oxide material and a second material that is different from the first material;

forming a first chemical mixture by plasma-excitation of a first process gas containing an inert gas and at least one additional gas selected from the group consisting of He and H₂;

exposing the first material on the substrate to the first chemical mixture to modify a first region of the first material;

thereafter, forming a second chemical mixture by plasma-excitation of a second process gas containing an inert gas and an additional gas containing C, H, and F; and

exposing the first material on the substrate to the second plasma-excited process gas to selectively etch the first material relative to the second material and remove the modified first material from the first region of the substrate.

2. The method of claim 1, wherein the first material is conformally applied to a mandrel pattern formed on the substrate, the mandrel pattern including features protruding from the substrate separated by open spaces.

3. The method of claim 2, wherein the first region of the substrate includes the top surface of the features in the mandrel pattern and the bottom surfaces of the open spaces in the mandrel pattern, and wherein the removal of the modified first material from the mandrel pattern leaves the first material remaining on the sidewalls of the mandrel pattern.

4. The method of claim 1, wherein the first process gas consists of Ar and He, or Ar and H₂.

5. The method of claim 1, wherein the second process gas includes a compound of the form C_xH_yF_z, and x, y, and z are integers greater than 0.

6. The method of claim 1, wherein the second process gas contains CHF₃.

7. The method of claim 1, wherein the second process gas consists of CHF₃ and Ar.

8. The method of claim 1, wherein the first material includes silicon oxide conformally applied to a pattern mandrel.

9. The method of claim 1, wherein the second material includes a carbon-containing soft or hard mask.

10. The method of claim 1, wherein the second material includes silicon.

11. The method of claim 1, wherein the second material includes Si, Ge, or a metal (M), and optionally one or more elements selected from the group consisting of O, N, C, F, Cl, Br, and S.

12. The method of claim 1, wherein the second material includes silicon, silicon oxide, silicon carbide, metal, metal oxide, metal nitride, metal carbide, or metal alloy, or combinations thereof.

13. The method of claim 1, wherein the second material includes a Si-containing anti-reflective coating (ARC), silicon or silicon oxide.

14. The method of claim 1, further comprising:

modifying exposed surfaces of the first material to a finite depth to form a modified sub-layer in the first material during the exposing to the first chemical mixture; and

etching the modified sub-layer in the first material during the exposing to the second chemical mixture.

15. The method of claim 14, further comprising:

forming a protection layer over the second material during the exposing to the second chemical mixture.

16. The method of claim 15, further comprising:

removing the protection layer over the second material during the exposing to the first chemical mixture.

17. The method of claim 1, wherein the plasma excitation of the first process gas or the second process gas includes generating plasma using a capacitively coupled plasma source containing an upper plate electrode, and a lower plate electrode supporting the substrate.

18. The method of claim 1, wherein the plasma excitation of the first process gas or the second process gas includes generating plasma using an inductively coupled plasma source containing an inductive element, and a lower plate electrode supporting the substrate.

19. The method of claim 1, wherein the plasma excitation of the first process gas or the second process gas includes generating plasma using a remote plasma source.

20. The method of claim 1, further comprising:

repeating the steps of forming the first chemical mixture, exposing the first material to the first chemical mixture, forming the second chemical mixture, and exposing the first material to the second chemical mixture to incrementally remove additional portions of the first material.