Perpendicular interface resistances of sputtered Ag/Cu, Ag/Au, and Au/Cu multilayers

Abstract

We report measurements of the increase in perpendicular specific resistance (area times total resistance, ${\mathit{AR}}_{\mathit{t}}$) of multilayers of two nonmagnetic metals with increasing number of interfaces, when the total amount of each metal is held constant. For multilayers of Ag and Cu, Ag and Au, and Au and Cu sputtered under narrowly defined conditions, we find, per interface, ${\mathit{AR}}_{\mathrm{A}\mathrm{g}/\mathrm{C}\mathrm{u}}$=0.044\ifmmode\pm\else\textpm\fi{}0.003 f\ensuremath{\Omega} ${\mathrm{m}}^{2}$; ${\mathit{AR}}_{\mathrm{A}\mathrm{g}/\mathrm{A}\mathrm{u}}$=0.050\ifmmode\pm\else\textpm\fi{}0.004 f\ensuremath{\Omega} ${\mathrm{m}}^{2}$; ${\mathit{AR}}_{\mathrm{A}\mathrm{u}/\mathrm{C}\mathrm{u}}$=0.149\ifmmode\pm\else\textpm\fi{}0.006 f\ensuremath{\Omega} ${\mathrm{m}}^{2}$. From independent estimates of the contributions to these values due to interface alloying, we conclude that such alloying can account for at least half and perhaps all of these values. These interface resistances are thus mostly not intrinsic. \textcopyright{} 1996 The American Physical Society.