Structural and Magnetic Properties of CoNbZr/SiO_2 Multilayer Films

摘要

The structural and magnetic properties of CoNbZr/SiO_2 multilayer films were investigated. Effects of the surface roughness of SiO_2 layers on the properties of CoNbZr/SiO_2 multilayer films were analyzed. The minimum coercivity 3.73 Oe and the maximum permeability at 100 MHz of 1783 was observed in (Co_(89.3)Nb_(6.1)Zr_(4.6) 100 nm / SiO_2 8 nm) multilayer films deposited at 130 W and 2 mTorr for CoNbZr films and 200 W and 2 mTorr(Ar/H_2 20 percent) for SiO_2 films. When sputtering gas pressure for SiO_2 films increased from 2 mTorr to 6 mTorr, the optimum thickness of SiO_2 layers increased from 10 nm to 25 nm It is thought that degradation of efficiency of insulation was resulted from increase of surface roughness of SiO_2 layers. Futhermore, by the addition of 20 percent H_2 gas to sputtering gas, the surface roughness of SiO_2 layers decreased from 7.4 A to 2.14 A so that soft magnetic properties were improved. When multilayer was annealed for 90 mm at 300 deg C, we obtained anisotropy field of 14 Oe, permeability at 100 MHz of 2800. That is considered that the major factor of annealing effect is both reduction of defects and increase of anisotropy in initial stage, but reduction of defects only in later stage.