Ion assisted deposition for rare-earth oxide based coatings

A method comprising:

• performing ion assisted deposition to deposit a first conformal protective layer on at least one surface of a chamber component for a processing chamber, wherein the at least one surface has a first average surface roughness of approximately 8-16 micro-inches, wherein the first conformal protective layer has the first average surface roughness after deposition, and wherein the first conformal protective layer is a plasma resistant rare earth oxide ceramic film having a substantially uniform thickness of less than 300 μm over the at least one surface that is selected from a group consisting of Y4Al2O9, Er2O3, Gd2O3, Nd2O3, YF3, Er4Al2O9, ErAlO3, Gd4Al2O9, GdAlO3, Nd4Al2O9, NdAlO3, a first ceramic compound comprising Y4Al2O9 and a solid-solution of Y2O3—ZrO2, and a second ceramic compound comprising a mixture of Y2O3, ZrO2, Er2O3, Gd2O3 and SiO2, and
• polishing the first conformal protective layer to a second average surface roughness of less than 10 micro-inches, wherein the second average surface roughness is less than the first average surface roughness.