Multilayer ALD coating for critical components in process chamber

A method for forming a protective coating on an article for semiconductor processing, the method comprising:

• loading the article for semiconductor processing in an atomic layer deposition (ALD) chamber;
• forming a first coating directly on a surface of an article using a first ALD process, the first coating comprising amorphous rare earth metal-containing oxide and characterized by a first thickness, the first ALD process comprising a first number of repetitions of three cycles of alumina deposition followed by two cycles of rare earth metal oxide deposition to reach the first thickness, wherein the first coating comprises a plurality of composite layers, wherein each composite layer includes an amorphous rare earth metal-containing oxide layer on an amorphous alumina layer;
• forming a second coating on the first coating using a second ALD process, the second coating comprising crystalline rare earth metal oxide, the second coating characterized by a second thickness;
• forming a third coating on the second coating using a third ALD process, the third coating comprising amorphous rare earth metal-containing oxide and characterized by a third thickness, the third ALD process comprising a second number of repetitions of three cycles of alumina deposition followed by two cycles of rare earth metal oxide deposition to reach the third thickness, wherein a ratio of the first number of repetitions to the second number of repetitions is between about 100 and about 150, and a ratio of the first thickness to the third thickness is between about 100 and about 150;
• and
• forming a fourth coating on the third coating using a fourth ALD process, the fourth coating comprising crystalline rare earth metal oxide and characterized by a fourth thickness.

A method for processing a process kit used in a plasma processing chamber, the method comprising:

• loading the process kit in an atomic layer deposition (ALD) chamber;
• forming a first coating directly on a surface of the process kit using a first ALD process, the first coating comprising amorphous rare earth metal-containing oxide and characterized by a first thickness, the first ALD process comprising a first number of repetitions of three cycles of alumina deposition followed by two cycles of rare earth metal oxide deposition to reach the first thickness, wherein the first coating comprises a plurality of composite layers, wherein each composite layer includes an amorphous rare earth metal-containing oxide layer on an amorphous alumina layer;
• forming a second coating on the first coating using a second ALD process, the second coating comprising crystalline rare earth metal oxide, the second coating characterized by a second thickness;
• forming a third coating on the second coating using a third ALD process, the third coating comprising amorphous rare earth metal-containing oxide and characterized by a third thickness, the third ALD process comprising a second number of repetitions of three cycles of alumina deposition followed by two cycles of rare earth metal oxide deposition to reach the third thickness, wherein a ratio of the first number of repetitions to the second number of repetitions is between about 100 and about 150, and a ratio of the first thickness to the third thickness is between about 100 and about 150;
• forming a fourth coating on the third coating using a fourth ALD process, the fourth coating comprising crystalline rare earth metal oxide and characterized by a fourth thickness;
• and
• assembling the process kit in the plasma processing chamber.