METHOD OF ETCHING SILICON NITRIDE FILMS

• US 20130344702A1
• Filed: 03/03/2012
• Published: 12/26/2013
• Est. Priority Date: 03/04/2011
• Status: Abandoned Application

• Current Assignee: Tokyo Electron Limited
• Original Assignee: Tokyo Electron Limited
• Inventors: Nishizuka, Tetsuya
• Application Number:
  US14/002,477
• Publication Number:
  US 20130344702A1
• Time in Patent Office: Days
• US Class Current: 438/724
• CPC Class Codes: H01L 21/3065 Plasma etching; Reactive-ion etching
• CPC Class Codes: H01L 21/31116 by dry-etching
• CPC Class Codes: H01L 21/31144 using masks

Abstract

A processing method is provided for plasma etching features in a silicon nitride (SiN) film covered by a mask pattern. The method includes providing a film stack on a substrate, the film stack containing a SiN film on the substrate and a mask pattern on the SiN film, transferring the mask pattern to the SiN film by exposing the film stack to a first plasma containing a carbon-fluorine-containing gas, O₂ gas, and optionally HBr gas, and exposing the film stack to a second plasma containing a carbon-fluorine-containing gas, O₂ gas, a silicon-fluorine-containing gas, and optionally HBr gas.

Claims

1. A method for processing a substrate, comprising:

providing a film stack on a substrate, the film stack containing a silicon nitride (SiN) film on the substrate and a mask pattern on the SiN film;

forming a first plasma from a first process gas containing a carbon-fluorine-containing gas and O₂ gas;

performing a main etch (ME) step by exposing the film stack to the first plasma;

forming a second plasma from a second process gas containing a carbon-fluorine-containing gas, O₂ gas, and a silicon-fluorine-containing gas; and

performing an over etch (OE) step by exposing the film stack to the second plasma.

2. The method of claim 1, wherein the ME step transfers the mask pattern to the SiN film by etching through less than an entire thickness of the SiN film, and thereafter, etching through a remaining thickness of the SiN film and stopping on the substrate in the OE step.

3. The method of claim 1, wherein the carbon-fluorine-containing gas comprises a fluorocarbon gas, a hydrofluorocarbon gas, or both a fluorocarbon gas and a hydrofluorocarbon gas.

4. The method of claim 3, wherein the first process gas, the second process gas, or both the first and second process gases further contain HBr gas.

5. The method of claim 3, wherein the hydrofluorocarbon gas contains or consists of CHF₃, CH₂F₂, or CH₃F, or a combination thereof.

6. The method of claim 3, wherein the fluorocarbon gas contains or consists of CF₄.

7. The method of claim 1, wherein the silicon-fluorine-containing gas contains SiF₄, SiHF₃, SiH₂F₂, or SiH₃F, or a combination thereof.

8. The method of claim 1, wherein the first process gas contains CH₃F gas, CF₄ gas, O₂ gas, Ar gas, and HBr gas, and the second process gas contains CH₃F gas, CF₄ gas, O₂ gas, HBr gas, Ar gas, and SiF₄ gas.

9. The method of claim 1, further comprising

applying RF bias power to a substrate holder supporting the substrate.

10. The method of claim 1, further comprising

applying pulsed RF bias power to a substrate holder supporting the substrate.

11. The method of claim 10, further comprising:

applying a first pulsed RF bias power to the substrate holder during the ME step; and

applying a second pulsed RF bias power to the substrate holder during the OE step.

12. The method of claim 11, wherein the first pulsed RF bias power is greater than the second pulsed RF bias power applied to the substrate holder.

13. The method of claim 1, wherein forming the first and second plasmas includes exciting the first and second process gases by a microwave plasma source including a radial line slot antenna (RLSA).

14. The method of claim 1, wherein the mask pattern comprises a SiON film, a SiO₂ film, or a combination thereof.

15. The method of claim 1, wherein the substrate comprises a Si film, a SiO₂ film, or a combination thereof.

16. The method of claim 1, wherein the first and second process gases further include Argon (Ar) gas or Helium (He) gas.

17. A method for processing a substrate, comprising:

providing a film stack on a substrate, the film stack containing a silicon nitride (SiN) film on the substrate and a mask pattern on the SiN film;

forming a first plasma from a first process gas containing a fluorocarbon gas, O₂ gas, and HBr gas;

performing a main etch (ME) step by exposing the film stack to the first plasma;

forming a second plasma from a second process gas containing a fluorocarbon gas, O₂ gas, HBr gas, and a silicon-fluorine-containing gas; and

performing an over etch (OE) step by exposing the film stack to the second plasma.

18. The method of claim 17, wherein the first process gas contains CF₄ gas, HBr gas, O₂ gas, and Ar gas, and the second process gas contains CF₄ gas, HBr gas, O₂ gas, Ar gas, and SiF₄ gas.

19. A method for processing a substrate, comprising:

providing a film stack on a substrate, the film stack containing a silicon nitride (SiN) film on the substrate and a mask pattern on the SiN film;

forming a first plasma from a first process gas containing a hydrofluorocarbon gas and O₂ gas;

performing a main etch (ME) step by exposing the film stack to the first plasma;

forming a second plasma from a second process gas containing a hydrofluorocarbon gas, O₂ gas, and a silicon-fluorine-containing gas; and

performing an over etch (OE) step by exposing the film stack to the second plasma.

20. The method of claim 19, wherein the first process gas contains CH₃F gas, O₂ gas, and Ar gas, and the second process gas contains CH₃F gas, O₂ gas, and SiF₄ gas.