Patent ID: 7166507

Claim:
A method for forming wire lines and interconnecting contacts, the method comprising; depositing a wire line layer, wherein depositing the wire line layer comprises depositing a metal layer consisting of a metal over a plurality of buried contact pads; depositing a multi-layered hard mask layer on the wire line layer, the multi-layered hard mask layer including at least a first hard mask layer, a second hard mask layer, and a third hard mask layer, each of the first, second, and third hard mask layers formed of different insulating materials to have an etch selectivity with respect to each other; patterning the multi-layered hard mask layer using a photoresist pattern to produce a multi-layered hard mask; patterning the wire line layer using the multi-layered hard mask to form bit lines; filling gaps between the wire lines with an insulating layer; and forming interconnecting contacts that align with the wire lines and vertically penetrate the insulating layer where the first hard mask is protected by the second hard mask.