INTERLAYER COMPOSITION AND INTERFACE STABILITY OF MO/SI MULTILAYERS STUDIED WITH HIGH-RESOLUTION RBS

Mo/Si multilayers with a period thickness of approximately 7.5 nm have been fabricated by e--beam evaporation in UHV at a deposition temperature of 150-degrees-C [1]. At their interfaces interlayers of mixed Mo and Si are obtained which are thicker at the Mo-on-Si than at the Si-on-Mo interface. The composition of as-deposited Mo/Si multilayers and bilayers and changes in the composition after baking the samples have been studied with high-resolution RBS. Differences in the behaviour of the two interfaces with baking are observed. The interdiffusion of Mo and Si starts mainly at the Mo-on-Si interface. The thickness of the interlayer at the Mo-on-Si interface increases with baking temperature. With the increasing thickness the Si/Mo mixture in the interlayer changes from Mo-rich to Si-rich. After baking at temperatures higher than 600-degrees-C strong Si diffusion into Mo is observed for both interfaces.