In some embodiments, the present disclosure relates to a method of trimming an annular portion of a wafer. The method includes aligning the wafer over a wafer chuck. The method uses a rotating blade having a first rotational speed to remove the annular portion from an upper surface of the wafer. While the rotating blade is removing the annular portion of the upper surface of the wafer, measuring a parameter of the wafer at a position adjacent to the rotating blade. Lastly, the method involves changing the first rotation speed of the rotating blade to a second rotational speed when the parameter is greater than a predetermined threshold.