US Patent 7563689 Method for fabricating nonvolatile memory device

A method for fabricating a nonvolatile memory device includes forming a gate insulation layer, a first gate conductive layer, a first sacrificial layer, and a second sacrificial layer over a substrate, etching the first and second sacrificial layers, the first gate conductive layer, the gate insulation layer, and the substrate to form trenches, forming a first insulation layer to fill the trenches, polishing the first insulation layer using the etched second sacrificial layer as a polish stop layer, removing the second sacrificial layer, recessing the first insulation layer inside the trenches, forming a second insulation layer to fill a space produced inside the trenches by the recessing of the first insulation layer, and polishing the second insulation layer using the etched first sacrificial layer as a polish stop layer.