Methods and apparatuses for combinatorial processing are disclosed. Methods include introducing a substrate into a processing chamber. Methods further include forming a first film on a surface of a first site-isolated region on the substrate and forming a second film on a surface of a second site-isolated region on the substrate. The methods further include exposing the first film to a plasma having a first source gas to form a first treated film on the substrate and exposing the second film to a plasma having a second source gas to form a second treated film on the substrate without etching the first treated film in the processing chamber. In addition, methods include evaluating results of the treated films post processing.