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Angle resolved x-ray photoelectron spectroscopy (ARXPS) has been employed to determine nondestructively the in-depth interface formation during thin film growth. Buried interfaces underneath the nanometer thick layers are probed by identifying the chemical shift of compound materials in photoelectron spectroscopy and using the angular response to quantify the compound amounts from the measured intensities. The thin interfaces in molybdenum-silicon multilayers grown at ambient temperature are investigated. This system is an example of an almost perfect 1D-system, where the interface region is only a small part of the individual layer thicknesses of 3 to 5 nm. Despite the low growth temperature, both the interfaces of this multilayer show layer thickness dependent interface formation. While the silicon-on-molybdenum interface shows a limited interface thickness of 0.4 nm of Mo5Si3, the molybdenum-on-silicon interface shows a more complex evolution. For this interface, the composition of the first 2.0 nm of deposited layer thickness is best described as a molybdenum-silicon compound layer with a molybdenum rich top and a MoSi2 bottom layer. After 2.5 nm of the deposited layer thickness, the molybdenum rich compound at the top has transformed into polycrystalline molybdenum on top of 1.8 nm MoSi2 at the interface. The formation of the 1.8 nm MoSi2 precedes the formation of polycrystalline molybdenum on top. Angle resolved x-ray photoelectron spectroscopy (ARXPS) is shown to be a good tool to study the interface phenomena beneath the nanometer thick top layers. In the case of Mo/Si multilayer mirrors, this ARXPS study shows that the compound formation at the interface accounts for the majority of the extreme ultraviolet reflectance loss. [ABSTRACT FROM AUTHOR]

Ion sputtering yields for Ru, Mo, and Si under Ar+ ion bombardment in the near-threshold energy range have been studied using an in situ weight-loss method with a Kaufman ion source, Faraday cup, and quartz crystal microbalance. The results are compared to theoretical models. The accuracy of the in situ weight-loss method was verified by thickness-decrease measurements using grazing incidence x-ray reflectometry, and results from both methods are in good agreement. These results provide accurate data sets for theoretical modeling in the near-threshold sputter regime and are of relevance for (optical) surfaces exposed to plasmas, as, for instance, in extreme ultraviolet photolithography. [ABSTRACT FROM AUTHOR]

Chemical diffusion and interlayer formation in thin layers and at interfaces is of increasing influence in nanoscopic devices, such as nanoelectronics and reflective multilayer optics. Chemical diffusion and agglomeration at interfaces of thin Ru, Mo, Si, and B4C layers have been studied with x-ray photoelectron spectroscopy, cross section electron energy loss spectroscopy, high-angle annular dark field scanning transmission electron microscopy, and energy dispersive x-ray in relation to observations in Ru-on-B4C capped Mo/Si multilayers. Rather than in the midst of the Si layer, silicides and borides are formed at the Si-on-Mo interface front, notably RuSix and MoBx. The interface apparently acts as a precursor for further chemical diffusion and agglomeration of B, Ru, and also other investigated d-metals. Reversed "substrate-on-adlayer" interfaces can yield entirely suppressed reactivity and diffusion, stressing the influence of surface free energy and the supply of atoms to the interface via segregation during thin layer growth. [ABSTRACT FROM AUTHOR]

Reflective Si/Mo multilayer mirrors with protective d-metal surfaces onto a range of upper Mo and Si layer thicknesses have been grown with physical vapor deposition and investigated on diffusion and in-depth compound formation. Laterally inhomogeneous upward Si and downward d-metal diffusion occurs through Mo layers up to 2 nm thickness. Especially Ru and Rh agglomerate and form silicides such as Ru2Si3 and Rh2Si not in the midst of the Si layer but at the Si/Mo interface. This appears to be mediated by MoSi2 presence at the Si/Mo interface that acts as precursor via better lattice compatibility and lowering of formation energy. [ABSTRACT FROM AUTHOR]

In situ weight-loss method with a Kaufman ion source, Faraday cup, and quartz crystal microbalance are used for studying the ion sputtering yields for Ru, Mo, and Si under [Ar.sup.+] ion bombardment in the near-threshold energy range. The results have provided accurate data sets for theoretical modeling in the near-threshold sputter regime and are relevant for optical surfaces exposed to plasmas in extreme ultraviolet photolithography.