A method includes performing ion beam sputtering with ion assisted deposition to deposit a protective layer on a surface of a body. The protective layer is a plasma resistant rare earth-containing film of a thickness less than 1000 µm. The porosity of the protective layer is below 1%. The plasma resistant rare earth-containing film consists of 40 mol% to less than 100 mol% of Y2O3, over 0 mol% to 60 mol% of ZrO2, and 0 mol% to 9 mol% of Al2O3.