METHOD OF EVALUATING THE UNIFORMITY OF THE THICKNESS OF THE POLYSILICON GATE LAYER

摘要

A method of evaluating the uniformity of the thickness of the polysilicon gate layer is provided. A substrate having a dense trenches area and a sparse trenches area is provided. A plurality of first trench isolation structures are formed in the sparse trenches area of the substrate and a plurality of second trench isolation structures are simultaneously formed in the dense trenches area of the substrate. A mask layer is formed between the gaps of the first and the second trench isolation structures. A portion of the first trench isolation structures of the sparse trenches area is then removed. Then, the mask layer is removed until the surface of the substrate is exposed. A polysilicon gate layer is formed over the substrate. Finally, a planarization process is performed to remove a portion of the polysilicon gate layer.