Selective atomic layer etching of semiconductor materials

• US 10,497,573 B2
• Filed: 03/13/2018
• Issued: 12/03/2019
• Est. Priority Date: 03/13/2018
• Status: Active Grant

• Current Assignee: Applied Materials Incorporated
• Original Assignee: Applied Materials Incorporated
• Inventors: Goradia, Prerna Sonthalia, Wang, Fei, Bajaj, Geetika, Ingle, Nitin, Li, Zihui, Visser, Robert Jan, Deepak, Nitin
• Primary Examiner(s): Ahmed, Shamim
• Application Number:
  US15/920,146
• Publication Number:
  US 20190287808A1
• Time in Patent Office: 630 Days
• Field of Search: None
• CPC Class Codes: C23F 1/12 Gaseous compositions
• CPC Class Codes: H01J 2237/332 Coating
• CPC Class Codes: H01J 2237/334 Etching
• CPC Class Codes: H01J 37/32357 Generation remote from the workpiece, e.g. down-stream
• CPC Class Codes: H01J 37/32422 Arrangement for selecting ions or species in the plasma
• CPC Class Codes: H01J 37/3244 Gas supply means
• CPC Class Codes: H01L 21/02205 the layer being characterised by the precursor material for deposition
• 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 21/3065 Plasma etching; Reactive-ion etching
• CPC Class Codes: H01L 21/3086 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 21/32136 using plasmas
• CPC Class Codes: H01L 21/32137 of silicon-containing layers
• CPC Class Codes: H01L 21/67069 for drying etching
• CPC Class Codes: H01L 21/67167 surrounding a central transfer chamber

Abstract

Precursors, such as interhalogens and/or compounds formed of noble gases and halogens, may be supplied in a gaseous form to a semiconductor processing chamber at a predetermined amount, flow rate, pressure, and/or temperature in a cyclic manner such that atomic layer etching of select semiconductor materials may be achieved in each cycle. In the etching process, the element of the precursor that has a relatively higher electronegativity may react with select semiconductor materials to form volatile etching byproducts. The element of the precursor that has a relatively lower electronegativity may form a gas that may be recycled to re-form an precursor with one or more halogen-containing materials using a plasma process.

Claims

1. An etching method comprising:

flowing a halogen-containing precursor into a processing region of a semiconductor processing chamber;

contacting an exposed region of a semiconductor material with the halogen-containing precursor such that the halogen-containing precursor is adsorbed on a surface of the exposed region of the semiconductor material;

forming a film of the halogen-containing precursor of a predetermined thickness on the surface of the exposed region of the semiconductor material;

pausing the flow of the halogen-containing precursor into the processing region of the semiconductor processing chamber; and

etching the exposed region of the semiconductor material with the adsorbed halogen-containing precursor, wherein the adsorbed halogen-containing precursor produces a fluoride of the semiconductor material.

2. The etching method of claim 1, further comprising purging the halogen-containing precursor not adsorbed on the surface of the exposed region of the semiconductor material.

3. The etching method of claim 1, wherein the film of the halogen-containing precursor formed on the surface of the exposed region of the semiconductor material comprises an atomic layer of the halogen-containing precursor.

4. The etching method of claim 1, wherein etching the exposed region of the semiconductor material comprises etching isotropically the exposed region of the semiconductor material.

5. The etching method of claim 1, wherein the adsorbed halogen-containing precursor further produces a noble gas.

6. The etching method of claim 1, wherein the halogen-containing precursor comprises at least one of a noble gas compound precursor, an interhalogen precursor, or a fluorinating precursor.

7. The etching method of claim 1, wherein the semiconductor material comprises at least one of silicon, germanium, or a compound thereof.

8. The etching method of claim 1, wherein a temperature of the semiconductor material is maintained at about room temperature.

9. The etching method of claim 1, wherein the etching method is repeated for at least two cycles, and wherein a thickness of the semiconductor material etched during each cycle is between about 5 Å

and about 50 Å

.

10. The etching method of claim 1, wherein the etching method has a selectivity toward the semiconductor material to a metal-containing material greater than or about 50:

1, and wherein the metal-containing material comprises at least one of titanium, titanium nitride, tantalum, tantalum nitride, tungsten, or titanium tungsten.

11. The etching method of claim 1, wherein a pressure within the semiconductor processing chamber is maintained between about 5 mTorr and about 50 Torr.

12. An etching method comprising:

flowing a halogen-containing precursor into a processing region of a semiconductor processing chamber;

contacting an exposed region of a metal-containing material with the halogen-containing precursor such that the halogen-containing precursor is adsorbed on a surface of the exposed region of the metal-containing material;

forming a film of the halogen-containing precursor on the surface of the exposed region of the metal-containing material;

pausing the flow of the halogen-containing precursor into the processing region of the semiconductor processing chamber; and

etching the exposed region of the metal-containing material with the adsorbed halogen-containing precursor, wherein the adsorbed halogen-containing precursor produces a fluoride of the metal-containing material.

13. The etching method of claim 12, further comprising purging the halogen-containing precursor not adsorbed on the surface of the exposed region of the metal-containing material such that an atomic layer of the halogen-containing precursor is produced on the surface of the exposed region of the metal-containing material.

14. The etching method of claim 12, wherein a temperature of the metal-containing material is maintained between about room temperature and about 300°

C.

15. The etching method of claim 12, wherein the metal-containing material comprises at least one of molybdenum, titanium, titanium nitride, tantalum, tantalum nitride, tungsten, or titanium tungsten.

16. The etching method of claim 12, wherein the halogen-containing precursor comprises XeF₂.

17. The etching method of claim 12, further comprising:

contacting an exposed region of a semiconductor material with the halogen-containing precursor such that the halogen-containing precursor is adsorbed on a surface of the exposed region of the semiconductor material;

forming a film of the halogen-containing precursor on the surface of the exposed region of the semiconductor material;

pausing the flow of the halogen-containing precursor into the processing region of the semiconductor processing chamber; and

etching the exposed region of the semiconductor material with the adsorbed halogen-containing precursor on the surface of the exposed region of the semiconductor material, wherein the adsorbed halogen-containing precursor produces a fluoride of the semiconductor material.

18. An etching method comprising:

flowing a first halogen-containing precursor into a processing region of a semiconductor processing chamber, wherein the first halogen-containing precursor comprises a noble gas compound precursor;

contacting an exposed region of a semiconductor material with the first halogen-containing precursor such that the first halogen-containing precursor is adsorbed on a surface of the exposed region of the semiconductor material;

etching the exposed region of the semiconductor material with the adsorbed first halogen-containing precursor, wherein the adsorbed first halogen-containing precursor produces a gaseous byproduct; and

forming a second halogen-containing precursor from the gaseous byproduct using plasma.

19. The etching method of claim 18, further comprising:

flowing the second halogen-containing precursor into the processing region of the semiconductor processing chamber;

contacting the exposed region of the semiconductor material with the second halogen-containing precursor such that the second halogen-containing precursor is adsorbed on the surface of the exposed region of the semiconductor material; and

etching the exposed region of the semiconductor material with the adsorbed second halogen-containing precursor, wherein the adsorbed second halogen-containing precursor produces a fluoride of the semiconductor material.

20. The etching method of claim 18, wherein the gaseous byproduct comprises at least one of a noble gas or a halogen gas.