Aperture geometry of magnetron sputtering unit was modified by insertion of longitudinal [B] and transverse [A] slits with respect to the motion of substrate. Fe-, Si-mono and Fe/Si multilayer [Fe (70 angstrom)/Si (50 angstrom)](10) (called ML70) were grown with and without modified apertures. Maximum stress anisotropy was found in samples prepared with transverse modified aperture [A]. X-ray reflectometry (XRR) results showed a marked difference in roughness values of interdiffusion layers Fe- Si and Si-Fe. Magnetic measurements showed coercive field strength of 50 Oe in ML70 prepared by modified aperture geometry Fe[A]/Si[O]. A significant improvement in the neutron polarization efficiency is observed in multilayer ML70 with the use of modified aperture geometry as compared to similar sample prepared by normal aperture. (C) 2009 Elsevier B. V. All rights reserved.