METHOD FOR ACHIEVING ULTRA-HIGH SELECTIVITY WHILE ETCHING SILICON NITRIDE

• US 20160247688A1
• Filed: 04/01/2015
• Published: 08/25/2016
• Est. Priority Date: 02/23/2015
• Status: Active Grant

• Current Assignee: Lam Research Corporation
• Original Assignee: Lam Research Corporation
• Inventors: Zhu, Helen H., Marquez, Linda, Yaqoob, Faisal, Park, Pilyeon, Berry, Ivan L. III, Angelov, Ivelin A., Park, Joon Hong
• Granted Patent: US 9,911,620 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: H01J 37/32357 Generation remote from the workpiece, e.g. down-stream
• CPC Class Codes: H01L 21/31116 by dry-etching

Abstract

Methods of selectively etching silicon nitride on a semiconductor substrate by providing silicon to the plasma to achieve high etch selectivity of silicon nitride to silicon-containing materials are provided. Methods involve providing silicon from a solid or fluidic silicon source or both. A solid silicon source may be upstream of a substrate, such as at or near a showerhead of a process chamber, or in a remote plasma generator. A silicon gas source may be flowed to the plasma during etch.

Claims

1. A method of etching silicon nitride on a substrate, the method comprising:

(a) introducing a fluorinating gas to a plasma generator and igniting a plasma to form fluorine-containing etching species; and

(b) providing silicon to the plasma from a silicon source;

(c) exposing the silicon nitride to the etching species to selectively etch the silicon nitride relative to other silicon-containing materials on the substrate.

2. The method of claim 1, wherein the silicon source is provided to the plasma upstream of the substrate.

3. The method of claim 1, wherein the silicon source is provided to the plasma in a remote plasma generator.

4. The method of claim 1, wherein the silicon source is provided to the plasma between the substrate and a showerhead of a chamber housing the substrate.

5. The method of claim 1, wherein the silicon source is provided to the plasma at or near a showerhead of a chamber housing the substrate.

6. The method of claim 1, wherein the silicon source comprises two or more silicon sources.

7. The method of claim 1, wherein the silicon source is a solid.

12. The method of claim 7, wherein the silicon source is attached to a wall of the plasma generator.

13. The method of claim 1, wherein the silicon source is fluidic.

15. The method of claim 13, wherein the silicon source is a silicon-containing compound selected from the group consisting of silane, disilane, silicon tetrafluoride, tetrachlorosilane, tetraethyl orthosilicate, and tetramethylsilane.

21. The method of claim 1, wherein the fluorinating gas is selected from the group consisting of F₂, SF₆, CF₄, CHF₃, CH₂F₂, NF₃, and combinations thereof.

8-11. -11. (canceled)

14. (canceled)

16-20. -20. (canceled)

22. A method of processing a substrate, the method comprising:

selectively etching silicon nitride relative to other silicon-containing materials on the substrate by providing silicon to a plasma from a silicon source,

wherein the plasma forms an etching species used to selectively etch the silicon nitride.

23. An apparatus for processing semiconductor substrates, the apparatus comprising:

(a) one or more stations, each station comprising a showerhead and a pedestal for holding a substrate comprising silicon nitride;

(b) at least one outlet for coupling to a vacuum;

(c) one or more process gas inlets for coupling to gas sources;

(d) a silicon source;

(e) a plasma generator; and

(f) a controller for controlling operations in the apparatus, comprising machine-readable instructions for;

(i) introducing gases comprising a fluorinating gas to the plasma generator and igniting a plasma to form an etching species;

(ii) introducing the etching species to the one or more stations,

wherein the silicon source is provided to the plasma during (i) and (ii).

24. The apparatus of claim 23, wherein the silicon source comprises two or more silicon sources, each of which is either a solid or gas.

25. The apparatus of claim 23, wherein the silicon source is upstream of the substrate.

27. The apparatus of claim 23, wherein the silicon source is a solid.

30. The apparatus of claim 27, wherein the silicon source is a silicon-containing compound selected from silicon, silicon germanium, silicon carbide, and silicon oxide.

31. The apparatus of claim 23, wherein the silicon source is fluidic.

32. The apparatus of claim 31, wherein the silicon source is a silicon-containing compound selected from the group consisting of silane, disilane, silicon tetrafluoride, tetrachlorosilane, tetraethyl orthosilicate, and tetramethylsilane.

34. The apparatus of claim 23, wherein the fluorinating gas is selected from the group consisting of F₂, SF₆, CF₄, CH₂F₂, NF₃, and combinations thereof.

26. (canceled)

28-29. -29. (canceled)

33. (canceled)

35-37. -37. (canceled)