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

Abstract

Individual layers of Ni0.8Fe0.2, Ni0.8Fe0.13Co0.07, TaN, and CrSi, and a full magnetic random access memory stack consisting of NiFeCo/CoFe/Cu/CoFe/NiFeCo/TaN/CrSi multilayers, were etched in high density Cl2/Ar plasmas either with or without concurrent ultraviolet (UV) illumination. Under optimized conditions, etch rate enhancement up to a factor of 5 was obtained for NiFeCo, TaN, and CrSi with UV illumination; whereas the etch rate of NiFe was retarded. Post-etch cleaning with H2 or SF6 plasmas or H2O rinsing was necessary in all cases in order to prevent corrosion of the metal layers from chlorinated etch residues. © 2000 American Institute of Physics.