Methods for fabricating nanowire for semiconductor applications

1. A method of forming nanowire structures on a substrate comprising:

supplying an oxygen containing gas mixture to a multi-material layer on a substrate in a processing chamber, wherein the multi-material layer includes repeating pairs of a first layer and a second layer, the first and the second layers having a first group and a second group of sidewalls respectively exposed through openings defined in the multi-material layer, wherein the second layer comprises a silicon and germanium containing material;

maintaining the oxygen containing gas mixture in the processing chamber at a process pressure at greater than 5 bar;

preferentially reacting silicon elements from the silicon and germanium containing material of the second layer with oxygen elements from the oxygen containing gas mixture; and

selectively forming an oxidation layer on the second group of sidewalls in the second layer in the presence of the oxygen containing gas mixture, wherein a ratio of an oxidation rate of the second group of sidewalls to the first group of sidewalls is greater than 5:1.

2. The method of claim 1 , wherein supplying the oxygen containing gas mixture further comprises:

maintaining a substrate temperature at greater than 200 degrees Celsius.

3. The method of claim 1 , wherein oxygen containing gas mixture includes at least an oxygen containing gas selected from a group consisting of O 2 , O 3 , H 2 O, H 2 O 2 , or steam.

4. The method of claim 1 , wherein oxygen containing gas mixture includes steam.

5. The method of claim 1 , wherein the first layer of the multi-material layer is an intrinsic silicon layer and the second layer of the multi-material layer is a SiGe layer while the substrate is a silicon substrate.

6. The method of claim 1 , further comprising:

forming horizontal gate-all-around (hGAA) structures using the openings defined in the multi-material layer.

7. The method of claim 1 further comprising:

performing a cleaning process to remove oxide residuals from the substrate.

8. The method of claim 1 , wherein the multi-material layer includes at least 2 repeating pairs.

9. The method of claim 1 , wherein the oxidation layer has thickness between about 1 nm and about 10 nm.

10. The method of claim 1 , wherein maintaining the process pressure at greater than 5 bar further comprises:

maintaining the process pressure at between about 10 bar and about 60 bar.

11. The method of claim 1 , further comprising:

performing an epitaxial deposition process to form a shaped structure from the first group of the sidewalls from the first layers.

12. A method of forming nanowire structures on a substrate comprising:

predominantly forming an oxidation layer on a portion of a multi-material layer disposed on a substrate, wherein the multi-material layer includes repeating pairs of a first layer and a second layer, wherein the second layer comprises a silicon and germanium containing material, the first and second layers having a first group and a second group of sidewalls respectively exposed through openings defined in the multi-material layer, wherein the oxidation layer is selectively formed on the second group of the sidewalls in the second layer and a ratio of an oxidation rate of the second group of sidewalls to the first group of sidewalls is greater than 5:1, wherein predominately forming the oxidation layer further comprises:

preferentially reacting silicon elements from the silicon and germanium containing material of the second layer with oxygen elements supplied from an oxygen containing gas while forming the oxidation layer; and

maintaining a process pressure at greater than 5 bar while forming the oxidation layer.

13. The method of claim 12 , wherein the first layer of the multi-material layer is an intrinsic silicon layer and the second layer of the multi-material layer is a SiGe layer while the substrate is a silicon substrate.

14. The method of claim 12 , wherein the multi-material layer is utilized to form nanowires or channels in horizontal gate-all-around (hGAA) structures.

15. The method of claim 12 , further comprising:

maintaining a substrate temperature at greater than 200 degrees Celsius while forming the oxidation layer.

16. The method of claim 12 , wherein the oxidation layer is formed by supplying an oxygen containing gas selected from a group consisting of O 2 , O 3 , H 2 O, H 2 O 2 , steam to the multi-material layer.

17. The method of claim 16 , wherein oxygen containing gas mixture includes steam or moisture.

18. A method of forming nanowire structures on a substrate comprising:

predominantly forming an oxidation layer on a portion of a multi-material layer disposed on a substrate, wherein the multi-material layer includes repeating pairs of a silicon layer and a SiGe layer, the silicon layer and the SiGe layer having a first group and a second group of sidewalls respectively exposed through openings defined in the multi-material layer, wherein the portion wherein the oxidation layer is selectively formed on is on the second group of the sidewalls in the SiGe layer, wherein a ratio of an oxidation rate of the second group of sidewalls to the first group of sidewalls is greater than 5:1, wherein predominately forming the oxidation layer further comprises:

preferentially reacting silicon elements from the silicon and germanium containing material of the second layer with oxygen elements supplied from an oxygen containing gas while forming the oxidation layer; and

maintaining a process pressure at greater than 5 bar while forming the oxidation layer.

19. The method of claim 18 , the oxidation layer is formed by supplying steam or moisture to the multi-material layer.

20. The method of claim 18 , further comprising:

maintaining a substrate temperature at between about 300 degrees Celsius and about 500 degrees Celsius while forming the oxidation layer.