The influence of Si concentration on the stress induced migration resistance and the electrical resistivity change from silicon precipitates of Al–Si–Cu and Al–Si–Cu/MoSi2interconnections was investigated. Electromigration of Al–Si–Cu/MoSi2was examined as a function of MoSi2thickness. A 1.5 wt. % Si concentration in aluminum alloy prevented grain growth and improved the stress induced migration resistance of the interconnections. However, this amount of Si addition caused resistance increases, because Si precipitates grew to the point that they were the same size as the interconnection linewidth. Layering of the Al–Si–Cu alloy containing 0.7 wt. % Si with MoSi2improved the stress induced migration resistance of aluminum interconnections and prevented the resistance increases. Furthermore, increasing MoSi2thickness improved electromigration resistance of layered interconnections. For MoSi2thickness of>30 nm, electromigration resistance was better than that of single layer Al–Si–Cu interconnections.