A method for forming a multilayer includes a process for forming a first conductive layer on a substrate; a process for forming a first insulating layer on the first conductive layer; a process for forming a second conductive layer on the first insulating layer and patterning the deposited second conductive layer; a process for forming a second insulating layer over the substrate so as to cover the patterned the second conductive layer; a process for forming a third insulating layer on the second insulating layer, wherein an etching speed of the third insulating layer is faster than that of the second insulating layer; and a process for forming contact holes at once that expose at least a part of the first conductive layer to the first insulating layer, the second insulating layer and the third insulating layer.