Independent control of etching and passivation gas components for highly selective silicon oxide/silicon nitride etching

Patent metadata

Field	Value
Publication number	US-11024508-B2
Application number	US-202016828308-A
Country	US
Kind code	B2
Filing date	Mar 24, 2020
Priority date	Apr 5, 2019
Publication date	Jun 1, 2021
Grant date	Jun 1, 2021

Abstract

A method for selective plasma etching of silicon oxide relative to silicon nitride is described. The method includes providing a substrate containing a silicon oxide film and a silicon nitride film, and selectively etching the silicon oxide film relative to the silicon nitride film by: a1) exposing the substrate to a plasma-excited passivation gas containing carbon, sulfur, or both carbon and sulfur, where the plasma-excited passivation gas does not contain fluorine or hydrogen, and b1) exposing the substrate to a plasma-excited etching gas containing a fluorine-containing gas. The method can further include, between a1) and b1), an additional step of a2) exposing the substrate to a plasma-excited additional passivation gas containing a fluorocarbon gas, hydrofluorocarbon gas, a hydrochlorocarbon gas, a hydrochlorofluorocarbon gas, or a hydrocarbon gas, or a combination thereof.

First claim

What is claimed is:

1. A plasma processing method, comprising:
providing a substrate containing a silicon oxide film and a silicon nitride film; and
selectively etching the silicon oxide film relative to the silicon nitride film by:
a1) exposing the substrate to a plasma-excited passivation gas containing carbon, sulfur, or both carbon and sulfur, wherein the passivation gas does not contain fluorine or hydrogen, and
b1) exposing the substrate to a plasma-excited etching gas containing a fluorine-containing gas.

2. The method of claim 1 , wherein step a1) forms a passivation layer that is thicker on the silicon nitride film than on the silicon oxide film.

3. The method of claim 1 , wherein the exposing steps a1) and b1) are performed alternatively and sequentially.

4. The method of claim 3 , further comprising
repeating the exposing steps a1) and b1) at least once to further selectively etch the silicon oxide film.

5. The method of claim 1 , wherein the plasma-excited etching gas includes F 2 , XeF 2 , ClF 3 , HF, NF 3 , or a combination thereof.

6. The method of claim 1 , wherein the plasma-excited etching gas does not contain a fluorocarbon gas or a hydrofluorocarbon gas.

7. The method of claim 1 , wherein the plasma excited passivation gas includes CO, COS, CS 2 , CCl 4 , C 2 Cl 4 , CCl 2 Br 2 , SCl 2 , S 2 Cl 2 , or a combination thereof.

8. The method of claim 1 , wherein the silicon oxide film includes SiO 2 and the silicon nitride film includes Si 3 N 4 .

9. The method of claim 1 , further comprising:
a2) exposing the substrate to a plasma-excited additional passivation gas containing a fluorocarbon gas, a hydrofluorocarbon gas, a hydrochlorocarbon gas, a hydrochlorofluorocarbon gas, a hydrocarbon gas, or a combination thereof.

10. The method of claim 9 , wherein the plasma-excited additional passivation gas contains CF 2 Cl 2 , CH 2 F 2 , CH 4 , CH 3 F, CHF 3 , C 4 H 6 , C 2 H 4 , C 3 H 6 , CH 2 Cl 2 , CH 3 Cl, CH 3 Cl, CH 2 ClF, CHCl 2 F, or a combination thereof.

11. The method of claim 9 , wherein the exposing steps a1), a2), and b1) are performed alternatively and sequentially in the order a1), followed by a2), and followed by b1).

12. The method of claim 9 , further comprising:
alternatively and sequentially repeating the exposing steps a1), a2), and b1) at least once to further selectively etch the silicon oxide film.

13. The method of claim 9 , wherein the exposing steps a1) and a2) at least partially overlap in time.

14. A plasma processing method, comprising:
providing a substrate containing a silicon oxide film and a silicon nitride film; and
selectively etching the silicon oxide film relative to the silicon nitride film by:
a1) exposing the substrate to a plasma-excited passivation gas, wherein the plasma excited passivation gas includes CO, COS, CS 2 , CCl 4 , C 2 Cl 4 , CCl 2 Br 2 , SCl 2 , S 2 Cl 2 , or a combination thereof, and wherein the passivation gas does not contain fluorine or hydrogen, and thereafter
b1) exposing the substrate to a plasma-excited etching gas containing F 2 , XeF 2 , ClF 3 , HF, NF 3 , or a combination thereof.

15. The method of claim 14 , wherein the plasma-excited etching gas does not contain a fluorocarbon gas or a hydrofluorocarbon gas.

16. A plasma processing method, comprising:
providing a substrate containing a silicon oxide film and a silicon nitride film; and
selectively etching the silicon oxide film relative to the silicon nitride film by:
a1) exposing the substrate to a plasma-excited passivation gas, wherein the plasma excited passivation gas includes CO, COS, CS 2 , CCl 4 , C 2 Cl 4 , CCl 2 Br 2 , SCl 2 , or S 2 Cl 2 , or a combination thereof, and wherein the passivation gas does not contain fluorine or hydrogen,
a2) exposing the substrate to a plasma-excited additional passivation gas containing a fluorocarbon gas, a hydrofluorocarbon gas, a hydrochlorocarbon gas, a hydrochlorofluorocarbon gas, a hydrocarbon gas, or a combination thereof, and thereafter
b1) exposing the substrate to a plasma-excited etching gas containing F 2 , XeF 2 , ClF 3 , HF, NF 3 , or a combination thereof.

17. The method of claim 16 , wherein the plasma-excited additional passivation gas contains CF 2 Cl 2 , CH 2 F 2 , CH 4 , CH 3 F, CHF 3 , C 4 H 6 , C 2 H 4 , C 3 H 6 , CH 2 Cl 2 , CH 3 Cl, CH 3 Cl, CH 2 ClF, CHCl 2 F, or a combination thereof.

18. The method of claim 16 , wherein the plasma-excited etching gas does not contain a fluorocarbon gas or a hydrofluorocarbon gas.

19. The method of claim 16 , wherein the exposing steps a1), a2), and b1) are performed alternatively and sequentially in the order a1), followed by a2), and followed by b1).

Assignees

• Tokyo Electron Ltd

Inventors

• Zhang Du
• Tsai Yu-Hao
• Wang Mingmei

Classifications

• H10P50/244 Primary

  comprising alternated and repeated etching and passivation steps · CPC title

• H10P50/283 Primary

  by chemical means · CPC title

• H01L21/30655 Primary

  Electricity · mapped topic

• H10P14/69215

  the material being a silicon oxide, e.g. SiO2 · CPC title

• H10P14/69433

  the material being a silicon nitride not containing oxygen, e.g. SixNy or SixByNz · CPC title