Ion assisted deposition top coat of rare-earth oxide

A method comprising:

• performing physical vapor deposition (PVD) with a metallic target consisting of an Erbium Aluminum Alloy to deposit a first protective layer consisting of a plasma resistant ceramic on at least one surface of an article, the article comprising a chamber component of a processing chamber, wherein the plasma resistant ceramic consists of Er3Al5O12 and has an amorphous structure;
• performing at least one of flowing Oxygen radicals from a first source into a deposition chamber containing the article at a flow rate or bombarding the article with Oxygen ions from a second source while performing the PVD, wherein the first source is a plasma source, and wherein the metallic target is evaporated or sputtered to react with at least one of the Oxygen radicals from the first source or the Oxygen ions from the second source and form the first protective layer consisting of the plasma resistant ceramic in situ as a result of the PVD;
• and
• depositing a second protective layer over the first protective layer, the second protective layer comprising Er2O3, wherein the second protective layer has a crystalline or nano-crystalline structure.