Corrosion-free dry etch patterning of magnetic random access memory stacks: Effects of ultraviolet illumination

Individual layers of Ni0.8Fe0.2, Ni0.8Fe0.13Co0.07, TaN, and CrSi, and a fu ll magnetic random access memory stack consisting of NiFeCo/CoFe/Cu/CoFe/Ni FeCo/TaN/CrSi multilayers, were etched in high density Cl-2/Ar plasmas eith er with or without concurrent ultraviolet (UV) illumination. Under optimize d conditions, etch rate enhancement up to a factor of 5 was obtained for Ni FeCo, TaN, and CrSi with UV illumination; whereas the etch rate of NiFe was retarded. Post-etch cleaning with H-2 or SF6 plasmas or H2O rinsing was ne cessary in all cases in order to prevent corrosion of the metal layers from chlorinated etch residues. (C) 2000 American Institute of Physics. [S0021- 8979(00)43708-4].