Also disclosed is that a system includes a factory interface, a plurality of load lock chambers, a buffer chamber, a plurality of process chambers, and at least one measuring device. The plurality of load lock chambers is coupled to the factory interface and configured to load and transfer wafers from the factory interface. The buffer chamber is coupled to the factory interface through the plurality of load lock chambers, and the buffer chamber is configured to receive the wafers from the plurality of load lock chambers. The plurality of process chambers is disposed around and coupled to the buffer chamber, and the plurality of process chambers is configured to process the wafers from the buffer chamber. The at least one measuring device is equipped in the factory interface, the at least one of the plurality of load lock chambers, the buffer chamber, or the combination thereof, to perform reflectance measurements to the wafers carried therein.

Also disclosed is that a method includes transferring a wafer from a factory interface through a load lock chamber to a buffer chamber, transferring the wafer from the buffer chamber to a process chamber, depositing the wafer by the process chamber to deposit a material on the wafer, and after the wafer is deposited, performing weight measurements to the wafer in the factory interface, the load lock chamber, the buffer chamber, or the combination thereof, to detect whether the material has a required thickness.