Mechanical Stresses and Magnetic Properties of NiFe and CoNiFe Films Obtained by Electrochemical Deposition

Magnetic films of NiFe permalloy and CoNiFe ternary alloy are used in products of nanoelectronics and microelectronics and in densely packed magnetic memory. NiFe and CoNiFe coatings decrease corrosion and wear in electrical devices; they are also used in electrocatalytic materials. Large stresses in magnetic films lead to deformations and the malfunctioning of devices due to peeling of the film from the silicon substrate. In this study, to clarify the nature of the phenomena occurring during the electrochemical deposition of NiFe and CoNiFe films of various thicknesses, which lead to mechanical stresses, investigation of their parameters is carried out. It is demonstrated that measurement of the bending of wafers consisting of Si, SiO 2 , Si 3 N 4 , NiCr, and Ni after the deposition of CoNiFe or NiFe layers on each of them allows determination of the mechanical stresses in the films. It is established that the beinding of the wafers with Si 3 N 4 is negative and greater than that with SiO 2 . The bending after depositing NiCr and Ni layers is negative. The bending of silicon wafers with CoNiFe ternary-alloy films has a maximum value of 180 μm at a film thickness of 12 μm, and that with NiFe films has a maximum value of 150 μm at a film thickness of 15 μm. The bending after depositing NiFe and CoNiFe films is positive. No peeling of the films is observed. The difference in the deformation signs of Ni and CoNiFe or NiFe films and in the direct dependence of the silicon-wafer bending on the thickness of NiFe and CoNiFe films makes it possible to relate the mechanical stresses to hydrogenation (hydrogen embrittlement) and hydrogen release after the process. It is determined that the magnetization of NiFe films is lower than that of triple CoNiFe films. The latter are promising for use in magnetic-field converters.