Adaptive endpoint method for pad life effect on chemical mechanical polishing

A semiconductor manufacturing method, comprising:

• performing a chemical mechanical polishing (CMP) process to a wafer positioned on a polishing pad in a CMP system;
• ending the CMP process at an endpoint determined by a life stage of the polishing pad, wherein the ending the CMP process includes determining the endpoint using an endpoint window having a window width particular to the life stage of the polishing pad;
• defining a plurality of life stages for the polishing pad;
• defining window widths for a plurality of endpoint windows associated with the plurality of life stages, respectively, according to the pad life effect;
• receiving a polishing signal of the CMP process;
• determining the life stage of the polishing pad based on a level of the polishing signal;
• associating one of the endpoint windows to the polishing signal according to the life stage of the polishing pad;
• and
• determining the endpoint by applying the one of the endpoint windows to the polishing signal.

A method comprising:

• defining a time region of pad life for a polishing pad in a chemical mechanical polishing (CMP) system;
• further comprising assigning a ladder coefficient to the polishing pad according to the time region of pad life;
• applying a CMP process to a wafer positioned on the polishing pad;
• determining whether the polishing pad is in the time region based on a level of a polishing signal being applied during the CMP process to the wafer;
• and
• ending the CMP process at an endpoint according to the time region of pad life for the polishing pad, wherein the ending the CMP process includes determining the endpoint using an endpoint window having a window width particular to the time region of the polishing pad.