Methods for wet clean of oxide layers over epitaxial layers
Methods for an oxide layer over an epitaxial layer. In an embodiment, a method includes forming an epitaxial layer of semiconductor material over a semiconductor substrate; forming an oxide layer over the epitaxial layer; applying a solution including an oxidizer to the oxide layer; and cleaning the oxide layer with a cleaning solution. In another embodiment, a densification process is applied to an oxide layer including treating with thermal energy, UV energy, or both. In an embodiment for a gate-all-around device, the cleaning process is applied to an oxide layer over an epitaxial portion of a fin. Additional methods are disclosed.
1. A method, comprising:
forming an epitaxial layer of semiconductor material over a semiconductor substrate;
forming an oxide layer over the epitaxial layer;
applying a solution including an oxidizer to the oxide layer; and
cleaning the oxide layer with a cleaning solution.
2. The method of claim 1 , wherein the solution including an oxidizer and the cleaning solution are the same solution.
3. The method of claim 1 , wherein the solution including an oxidizer includes one taken from the group consisting essentially of H 2 SO 4 , H 2 O 2 , O 3 , HNO 3 , and HCl.
4. The method of claim 1 , wherein the cleaning solution comprises one taken from the group consisting essentially of H 2 SO 4 :H 2 O 2 :H 2 O, NH 4 OH:H 2 O 2 :H 2 O, HCL:H 2 O 2 :H 2 O, O 3 :H 2 O, and HF:H 2 O, and combinations thereof.
5. The method of claim 1 , wherein the semiconductor substrate is a silicon substrate.
6. The method of claim 1 , wherein the epitaxial layer is a silicon germanium layer.
7. The method of claim 1 , wherein the epitaxial layer is a germanium layer.
8. The method of claim 1 , wherein the epitaxial layer is a III-V material layer.
9. A method, comprising:
forming a silicon fin over a silicon substrate;
forming a silicon germanium region over the silicon fin;
forming a silicon region over the silicon germanium region;
etching to expose a portion of the silicon germanium region;
performing oxidation to form an silicon germanium oxide layer in a portion of the silicon germanium region; and
treating the silicon germanium oxide layer with a solution including an oxidizer.
10. The method of claim 9 and further comprising subsequently cleaning the silicon germanium oxide layer with another solution.
11. The method of claim 9 , and further comprising, after treating the silicon germanium oxide layer with a solution:
performing a densification process on the silicon germanium oxide layer by applying one of thermal energy, UV energy, or a combination of thermal and UV energy to the silicon germanium oxide layer.
12. The method of claim 9 , and further comprising:
etching the silicon region to remove silicon oxide from the silicon region;
forming an interfacial layer on an exterior surface of the silicon region;
forming a gate dielectric layer on the interfacial layer; and
forming a conductive gate on the gate dielectric layer;
wherein the conductive gate and the gate dielectric are formed all around the silicon region.
13. A method, comprising:
forming an epitaxial layer over a silicon substrate;
performing an oxidation of the epitaxial layer to form an oxide layer containing unreacted atoms from the epitaxial layer;
treating the oxide with a solution including an oxidizer to form soluble oxide molecules with the unreacted atoms; and
wet cleaning the oxide with a solution to remove the soluble oxide molecules.
14. The method of claim 13 , wherein the epitaxial layer comprises germanium.
15. The method of claim 14 , wherein the epitaxial layer comprises silicon germanium.
16. The method of claim 15 , wherein the oxide layer comprises silicon germanium oxide.
17. The method of claim 14 , wherein the unreacted atoms comprise germanium atoms.
18. The method of claim 13 , wherein the solution including an oxidizer includes an oxidizer that is one taken from the group consisting essentially of H 2 SO 4 , H 2 O 2 , O 3 , HNO 3 , and HCl.
19. The method of claim 13 wherein the solution used in the wet cleaning includes one taken from the group consisting essentially of H 2 SO 4 :H 2 O 2 :H 2 O, NH 4 OH:H 2 O 2 :H 2 O, HCL:H 2 O 2 :H 2 O, O 3 :H 2 O; HF:H 2 O, SC-1, SC-2, APM, SPM, HPM, and combinations thereof.
20. The method of claim 13 wherein treating the oxide with a solution including an oxidizer and wet cleaning with a solution are performed simultaneously with a solution including H 2 SO 4 .