A combinatorial processing chamber is provided. The combinatorial processing chamber is configured to isolate a radial portion of a rotatable substrate support, which in turn is configured to support a substrate. The chamber includes a plurality of clusters process heads in one embodiment. An insert having a base plate disposed between the substrate support and the process heads defines a confinement region for a deposition process in one embodiment. The base plate has an opening to enable access of the deposition material to the substrate. Through rotation of the substrate and movement of the opening, multiple regions of the substrate are accessible for performing combinatorial processing on a single substrate.