MULTIPLE HARD MASK STRUCTURING FOR PRODUCING 20 NM MRAM DEVICES AND SMALLER

摘要

A method of etching a magnetic tunnel junction (MTJ) structure is described. A stack of MTJ layers on a lower electrode on a wafer is provided. A metal hard mask layer is provided on the MTJ stack. A stack of a plurality of dielectric hard masks is formed on the metal hard mask, each of the successive dielectric hard masks having an etch selectivity with respect to their underlying and overlying layers. The dielectric hard mask layers are in turn selectively etched with respect to their underlying and overlying layers, each successive feature size being smaller than the previous feature size. The MTJ stack is selectively etched with respect to the lowermost combination of dielectric and metal hard mask structures to form an MTJ device with an MTJ feature size that is smaller than a lowermost feature size.