Method for fabricating semiconductor device

Abstract

A method for fabricating a semiconductor device includes the steps of sequentially forming a pad oxide layer and a pad nitride layer on a substrate, the pad oxide layer including a first oxide layer formed on an upper surface of the substrate and a second oxide layer formed on a lower surface of the substrate, and the pad nitride layer including a first nitride layer formed on the upper surface of the substrate and a second nitride layer formed on the lower surface of the substrate; patterning the first nitride layer by removing a portion of the first nitride layer; forming a trench in the substrate corresponding to the removed portion of the first nitride layer, thereby patterning the first oxide layer; filling the trench with an insulating material to form a device isolation layer; forming a passivation layer on the substrate, the passivation layer including a first passivation layer formed on the upper surface of the substrate including the device isolation layer, and a second passivation layer formed on the lower surface of the substrate including the second oxide layer and the second nitride layer; and removing the first passivation layer, the patterned first oxide layer, and patterned first nitride layer.