Method of forming nonvolatile memory device

A method of forming the gate patterns of a nonvolatile memory device comprises stacking a gate insulating layer and a first conductive layer over a semiconductor substrate; forming isolation hard mask patterns over the first conductive layer; etching the first conductive layer using the isolation hard mask patterns as etch barriers, thus exposing the gate insulating layer; etching the gate insulating layer using the isolation hard mask patterns as etch barriers, thus exposing the semiconductor substrate; after exposing the semiconductor substrate, forming a passivation layer on the sidewalls of the first conductive layers and on the sidewalls of the gate insulating layers; and etching the semiconductor substrate using the passivation layer and the isolation hard mask patterns as etch barriers, thus forming trenches in the semiconductor substrate.