An assembly comprising a device wafer received in a recess of a carrier wafer. A device wafer comprising a protrusion terminating at an active surface bearing integrated circuitry, the protrusion surrounded by a peripheral flat extending to an outer periphery of the device wafer. A method of wafer thinning using the previously described carrier wafer and device wafer. Various implementations of a carrier wafer having a recess are also disclosed, as are methods of fabrication.