A chamber for combinatorially processing a substrate is provided. The chamber includes a first mask and a second mask that share a common central axis. The first mask and the second mask are independently rotatable around the common central axis. The first mask has a first plurality of radial apertures and the second mask has a second plurality of radial apertures. An axis of the first plurality of radial apertures is offset from an axis of the second plurality of radial apertures. A substrate support that is operable to support a substrate below the first and second masks is included. The substrate support shares the common central axis.