The present disclosure provides a semiconductor manufacturing method. The method includes defining a plurality of time regions of pad life for a polishing pad in a chemical mechanical polishing (CMP) system; assigning a ladder coefficient to the polishing pad according to the plurality of time regions of pad life; defining a plurality of endpoint windows to the plurality of time regions, respectively, according to pad life effect; applying a CMP process to a wafer positioned on the polishing pad; determining a time region of a polishing signal of the wafer based on the ladder coefficient; associating one of the endpoint windows to the polishing signal according to the time region; and ending the CMP process at an endpoint determined by the endpoint window.