Gas distribution showerhead and method of cleaning
During a deposition process, material may deposit not only on the substrate, but also on other chamber components. In a MOCVD chamber, one of those components is the gas distribution showerhead. The showerhead may be cleaned by bombarding the showerhead with radicals generated by a plasma that includes an inert gas and chlorine. In order to generate the plasma, the showerhead may be negatively biased or floating relative to the substrate support. The showerhead may comprise stainless steel and be coated with a ceramic coating.
1. A method, comprising:
introducing a cleaning gas to a processing chamber;
applying an electrical bias to a gas distribution showerhead that is coupled to the processing chamber while a substrate support disposed opposite the showerhead is electrically floating or grounded, the showerhead having a showerhead body comprising stainless steel having a roughened surface with a ceramic coating thereover facing the substrate support, the ceramic coating deposited on the roughened surface while controlling deposition pressure to form a desired roughness, the showerhead body having a plurality of first gas passages and a plurality of second gas passages extending therethrough, the electrical bias igniting the cleaning gas into a plasma containing cleaning gas radicals and ions;
reacting the cleaning gas radicals with deposits formed on the ceramic coating by bombarding the ceramic coating with the cleaning gas radicals to form a byproduct and expose the ceramic coating, the exposed ceramic coating having an emissivity within 2 percent of the emissivity of the ceramic coating prior to formation of the deposits thereon; and
exhausting the byproduct from the processing chamber.
2. The method of claim 1 , wherein the cleaning gas comprises a chlorine containing gas.
3. The method of claim 2 , wherein the chlorine containing gas is selected from the group consisting of Cl 2 , ICl, HCl, BCl 3 , CCl 4 , CH 3 Cl and combinations thereof.
4. The method of claim 3 , wherein the electrical bias is a negative electrical bias.
5. The method of claim 4 , wherein the pressure within the chamber during the cleaning is less than about 300 mTorr.
6. The method of claim 5 , wherein the electrical bias is between about 2.23 W/in 2 to about 16 W/in 2 .
7. A method, comprising:
performing a deposition process on one or more substrates in a processing chamber while changing the emissivity of a gas distribution showerhead from a first emissivity level to a second emissivity level;
removing the substrates from the processing chamber;
introducing a cleaning gas to a processing chamber;
applying an electrical bias to the gas distribution showerhead that is coupled to the processing chamber while a substrate support disposed opposite the showerhead is electrically floated or grounded, the showerhead having a showerhead body comprising stainless steel having a roughened surface and a ceramic coating thereover facing the substrate support, the ceramic coating deposited on the roughened surface while controlling deposition pressure to form a desired roughness, the showerhead body having a plurality of first gas passages and a plurality of second gas passages extending therethrough, the electrical bias igniting the cleaning gas into a plasma containing cleaning gas radicals and ions;
reacting the cleaning gas radicals with deposits formed on the ceramic coating by bombarding the ceramic coating with the cleaning gas radicals to form a byproduct and expose the ceramic coating, the exposed ceramic coating having a third emissivity level that is within 2 percent of the first emissivity level; and
exhausting the byproduct from the processing chamber.
8. The method of claim 7 , wherein the cleaning gas comprises a chlorine containing gas.
9. The method of claim 8 , wherein the chlorine containing gas is selected from the group consisting of Cl 2 , ICl, HCl, BCl 3 , CCl 4 , CH 3 Cl and combinations thereof.
10. The method of claim 9 , wherein the electrical bias is a negative electrical bias.
11. The method of claim 10 , wherein the deposition process is a MOCVD process.
12. The method of claim 11 , further comprising performing another deposition process on one or more additional substrates after exhausting the byproduct.
13. The method of claim 1 , wherein the cleaning occurs in-situ.