Abstract: A stacked structure for patterning a material layer to form an opening pattern with a predetermined opening width in the layer is provided. The stacked structure includes an underlayer, a silicon rich organic layer, and a photoresist layer. The underlayer is on the material layer. The silicon rich organic layer is between the underlayer and the photoresist layer. The thickness of the photoresist layer is smaller than that of the underlayer and larger than two times of the thickness of the silicon rich organic layer. The thickness of the underlayer is smaller than three times of the predetermined opening width.

Abstract: A dual damascene process is provided. A substrate having a conductive area is provided. An etching stop layer, a dielectric layer and a patterned hard mask layer are sequentially formed on the substrate. A first opening is formed in the dielectric layer exposed by the patterned hard mask layer. A first material layer having a high etching selectivity with respect to the dielectric layer is deposited to fill the first opening. A portion of the dielectric layer and the filling material layer are removed to form a trench and a second opening. The filling material layer exposed by the second opening is removed to expose part of the etching stop layer. A portion of the etching stop layer is removed to form a third opening. A conductive layer is formed in the trench and the third opening.