How to Observe Interfaces
A diode RF sputtering system is used to realize ultra thin layer stacks (2d ≃ 40 Å) of W and C or W and Si, for soft X-ray optics. Regulation of growth parameters allows to control thickness reproducibility with a good accuracy (0.04%). Low pressure (≃1 mTorr) minimizes interface roughness. However, intrinsic interface roughness limits multilayer performances as shown by X-ray reflexion computer simulations. In order to understand the interface formation process and structure we have used three methods.