Patent ID: 7696551

Claim:
A composite hard mask used for the fabrication of a MTJ cell in a MRAM device, comprising: (a) a lower non-magnetic metallic layer formed on a free layer in a MTJ stack of layers, said non-magnetic metallic layer essentially magnetically isolates said free layer from an overlying metallic spacer and has an etch rate substantially higher than an overlying upper conductive layer during an etch process comprised of one or more gases having a C, H, and O composition; (b) a middle metallic spacer that has an etch rate substantially lower than an overlying upper conductive layer during a fluorocarbon etch process that selectively removes portions of the upper conductive layer, and has an etch rate substantially higher than an overlying conductive layer during an etch process comprised of one or more gases having a C, H, and O composition; and (c) an upper conductive layer that has a substantial etch rate in regions exposed to a fluorocarbon etch but has a substantially high etch resistance to an etch process comprised of one or more gases having a C, H, and O composition.