International Business Machines Corporation
Large grain copper interconnect lines for MRAM

Abstract:

Large grain metal bitlines are formed above magnetic tunnel junction pillars used as MRAM bits without materially affecting the magnetic properties of the magnetic tunnel junctions. A copper or copper alloy bitline having relatively small grains is formed over the pillars. Laser annealing is employed to melt the bitline. Subsequent cooling and recrystallization results in a reduction of the number of grain boundaries in the bitline and a reduction in bitline effective resistivity. Multiple melt/cool cycles may be used. Bitline grains are vertically aligned with the pillars in a resulting structure.