A method for manufacturing a semiconductor device includes providing a dielectric layer over a substrate, providing a first photoresist layer over the dielectric layer, patterning and defining the first photoresist layer, etching the first photoresist layer and the dielectric layer to form a plurality of vertical openings, removing the first photoresist layer, depositing a second photoresist layer over the dielectric layer, wherein the second photoresist layer fills the plurality of vertical openings, removing only a portion of the second photoresist layer deposited over the dielectric layer, wherein the second photoresist layer has a first substantially uniform thickness over the dielectric layer, depositing an anti-reflection coating layer over the second photoresist layer, providing a third photoresist layer over the anti-reflection coating layer, patterning and defining the third photoresist layer, and etching the anti-reflection coating layer and the second photoresist layer to form a plurality of trenches in the dielectric layer.