Tuning the permeability of permalloy films for on-chip inductor applications

In this work, we demonstrate that the permeability of 1 mu m thick NiFe/Cr multilayer films can be tuned by varying the thickness of individual NiFe layers while keeping the total multilayer film thickness constant. Our results show that the permeability can be increased from 170 to 650 by varying the NiFe thicknesses from 100 to 50 nm. The thickness dependant permeability variation was attributed to the presence of stripe domains, as examined by hysteresis measurements and magnetic force microscope imaging. Films with thinner NiFe layers coupled with on-chip spiral inductors enable an inductance increase by a factor of 6. (C) 2010 American Institute of Physics. [doi: 10.1063/1.3502478]