A wafer processing tool is capable of detecting wafer warpage. The wafer processing tool includes a wafer holder on which a wafer is held and at least one sensor set. The at least one sensor set is disposed above the wafer or under the wafer, and a projection of each of the at least one sensor set on the wafer radially extending from a center of the wafer to an edge of the wafer. The at least one sensor set is configured to scan an entire surface of the wafer so as to measure warpage of the wafer while the wafer holder and the at least one sensor set are rotatable relative to each other.