Patent ID: 8409986

Claim:
A method for improving within die uniformity of the metal plug CMP process in the gate last route, comprises: providing a substrate, a metal gate on said substrate, and a contact hole area between the adjacent metal gates; depositing a metal layer on said substrate, said metal layer can at least completely fill said contact hole area, a step height exists between the upper surface of said metal layer in said contact hole area and said non-contact hole area, and the absolute value of said difference in height is denoted as H; planarizing said metal layer with a chemical mechanical planarization process to remove said redundant metal layer, so that said metal layer is only remained within said contact hole, and metal plugs with a flat top are formed; characterized in that, before said chemical mechanical planarization process, the method comprises the steps of: after depositing said metal layer, coating on said substrate a photo resist on which exposure with a photo mask is performed to form a photo resist pattern, wherein said photo resist pattern covers said metal layer of said contact hole area and exposes said metal layer of said non-contact hole area; etching the exposed metal layer said non-contact hole area with dry etching process, the etching depth of said etching process being smaller than or equal to H; after said etching process, the step height between the upper surface of said metal layer of said contact hole area and said non-contact hole area is reduced; removing said photo resist pattern on said substrate with a photo resist stripping process.