Method of removing tungsten near the wafer edge after CMP

摘要

A method is described for removing residual metal, such as tungsten, from the edge region of a wafer. After tungsten is deposited on a wafer to fill via holes in a dielectric the wafer is planarized using Chemical Mechanical Polishing, CMP. The CMP does not remove the tungsten from the edge of the wafer. After conductor metals for a layer of conducting electrodes has been deposited a layer of photoresist is formed on the wafer and patterned to clear the metals from over the alignment marks. This photoresist is then removed from the edge region of the wafer. The residual metals are then etched away from the edge region of the wafer using the remaining photoresist as a mask during the same etching step used to remove metals from the alignment marks or during a separate etching step. In one embodiment the alignment marks and laser marks are relocated to the edge region of the wafer and the residual metals are etched away from the edge region of the wafer during the same etching step used to remove metals from the alignment marks and laser marks.