Reference is made to FIG. 2. FIG. 2 is a measuring device 200 setup diagram, according to some embodiments of the present disclosure. The measuring device 200 includes a weight meter 210, a process driver 220, a data collection control unit 230, and a processor 240. For illustration in FIG. 2, the data collection control unit 230 is coupled to the weight meter 210. The process driver 220 is coupled to the data collection control unit 230. The weight meter 210, the process driver 220, and the data collection control unit 230 are coupled to the processor 240.

In some embodiments, the weight meter 210 is equipped at the buffer chamber 130. For illustration in FIG. 2, the weight meter 210 is positioned beneath the robot blade 132 of the robot 131 of the buffer chamber 130. During the measurement, the weight meter 210 is configured to make real-time weight measurement of the wafer W. When the measured weight is converted to a thickness corresponding to a material (not shown in FIG. 2), the weight meter 210 is, alternatively stated, configured to performed real-time thickness measurement of the material on the wafer W.