Method for removing aluminum fluoride contamination from aluminum-containing surfaces of semiconductor process equipment
View Patent ↗Described are methods of removing aluminum fluoride contaminants from aluminum, anodized aluminum, and sprayed ceramic surfaces. Hydrofluoric acid, long known to be effective at removing certain contaminants, has not been used to dissolve aluminum fluoride on aluminum-containing surfaces because the hydrofluoric acid strongly attacks such surfaces, and consequently damages sensitive components. Methods used in accordance with some embodiments remove aluminum fluoride using a mixture of hydrofluoric acid and one or more anhydrous acid. Suitable anhydrous acids include acetic acid.
1. A method for removing aluminum fluoride contamination from semiconductor process equipment, the semiconductor process equipment having an oxide of aluminum underlying the aluminum fluoride contamination, the method comprising applying a hydrofluoric-acid solution to the aluminum fluoride contamination, the hydrofluoric-acid solution including hydrofluoric acid and less than 25% water.
2. The method of claim 1 , further comprising preparing the hydrofluoric-acid solution by combining hydrofluoric acid and an anhydrous acid.
3. The method of claim 1 , further comprising combining hydrofluoric acid and citric acid to create the hydrofluoric-acid solution.
4. The method of claim 3 , further comprising saturating the hydrofluoric-acid solution with the citric acid.
5. The method of claim 1 , wherein the aluminum fluoride contamination comprises a byproduct of a plasma etching process.
6. The method of claim 1 , wherein the aluminum fluoride contamination comprises a byproduct of a plasma etching process that employs a fluorine-containing gas.
7. The method of claim 6 , wherein the fluorine-containing gas comprises nitrogen trifluoride.
8. The method of claim 1 , wherein the equipment comprises an aluminum alloy.
9. A method for removing aluminum fluoride contamination from semiconductor process equipment, the semiconductor process equipment having an exposed surface including at least one of aluminum, anodized aluminum, or a sprayed ceramic, the aluminum fluoride contamination being a byproduct of a plasma etch process that employs nitrogen trifluoride, the method comprising applying a hydrofluoric-acid solution to the exposed surface, the hydrofluoric-acid solution including between about 0.5% and 30% hydrofluoric acid, between about 50% and 99% acetic acid, and less than about 25% water.