Method and/or system for chemical mechanical planarization (CMP)

One or more methods or systems for performing chemical mechanical planarization (CMP) are provided. The system includes at least one of an emitter, a detector, a spectroscopic signal generator, a comparator, a spectral library, a controller or a CMP device. A spectroscopic signal is generated and is used to determine the thickness of a first material formed on or from a wafer by comparing the spectroscopic signal to a spectral library. Responsive to the thickness not being equal to the desired thickness, the controller instructs the CMP device to perform a rotation to reduce the thickness of the first material. The system and method herein increase the sensitivity of the CMP, such that the thickness of the first material is reduced with greater accuracy and precision, as compared to where the thickness is not measured between consecutive rotations of a wafer.