Method for manufacturing semiconductor device

摘要

A method for manufacturing a semiconductor device comprising: a first step of successively forming a silicon oxide film and a silicon nitride film on a silicon substrate, followed by forming a silicon nitride oxide film or a multilayered film containing the silicon nitride oxide film on the silicon nitride film; a second step of forming a photoresist film having an opening portion located at the position corresponding to an element isolation area of the silicon substrate on the silicon nitride film or the multilayered film according to a photolithography method; a third step of forming a trench having a pair of tapered side surface portions on the confronting side surfaces thereof on the silicon nitride oxide film or the multilayered film by using the photoresist film as a mask, the tapered side surface portions being inclined toward the substrate side so as to approach each other; and a fourth step of patterning the silicon nitride film and the silicon oxide film by dry etching by using the photoresist film and the silicon nitride oxide film or the multilayered film as a mask.