Selective atomic layer etching of semiconductor materials
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.
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 XeF 2 .
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.