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The reflectivity of Al/Zr multilayers is enhanced by the use of a novel structure. The Al layers are divided by insertion of Si layers. In addition, Si barrier layers are inserted at the Al/Zr interfaces (Zr-on-Al and Al-on-Zr). As a result, crystallization of the Al layer is inhibited and that of Zr is enhanced. In grazing incidence x-ray reflectometry, x-ray diffraction, and extreme ultraviolet measurements, the novel multilayers exhibit lower interfacial roughness compared with traditional multilayer structures, and their reflectivity is increased from 48.2% to 50.0% at a 5° angle of incidence. These novel multilayers also have potential applications in other multilayer systems and the semiconductor industry.

A systematic investigation of the structure, nature of the interface and their possible connections with magnetic properties for the as-deposited Co/Si/Co trilayer system has been carried out. X-ray reflectivity, cross-sectional transmission electron microscopy and x-ray emission measurements performed on the Co/Si/Co trilayer system show that when the Si layer thickness is less than ∼ 20 Å, the full Si layer is converted into a cobalt silicide layer whereas when the Si layer thickness > 20 Å along with the silicide layer. the pure Si layer also remains. A comparison of magneto-optical Kerr effect and magnetoresistance measurements reveals the absence of antiferromagnetic coupling in these samples. Double-step-like magnetization, in the case of Si layer thickness > 20 Å between two Co layers, is explained by magnetization reversal of two ferromagnetic layers having different coercivities, independent of each other.

Abstract: A methodology combining non-destructive X-ray techniques is proposed to study the interfacial zones of periodic multilayers. The used X-ray techniques are X-ray emission spectroscopy induced by electrons and X-ray reflectivity in the hard and soft X-ray ranges. The first technique evidences the presence of compounds at the interfaces and gives an estimation of the thickness of the interfacial zone. These informations are used to constrain the fit of the X-ray reflectivity curves that enables to determine the thickness and roughness of the various layers of the stacks. The results are validated in the soft X-ray range where the reflectivity curves are very sensitive to the chemical state of the elements present in the stack. The methodology is applied to characterize Mo/Si (1–4nm/2nm) and B4C/Mo/Si (1nm/2nm/2nm) multilayers. It is shown that the two interfacial zones of the Mo/Si multilayers are composed of the silicides MoSi2 and Mo5Si3. It is found that the interface thickness is about to be 0.4–0.8nm depending on the samples. The molybdenum silicides are also evidenced at the interfaces of the B4C/Mo/Si multilayers. However, their interface thickness is 0.2nm thinner than that of the same stack without the B4C layers, these layers being at the Mo-on-Si side or at the Si-on-Mo side. Thus, the B4C layers do not stop but only reduce the interdiffusion between the Mo and Si layers. [Copyright &y& Elsevier]

Abstract: We have tested and validated a non-destructive analysis method of multilayer structure, which combine X-ray emission spectroscopy and X-ray reflectometry at 0.154 and 1.33 nm. In this purpose, a series of Mo/Si and Mo/B4C/Si/B4C multilayers, deposited by magnetron sputtering, have been designed. The thickness of the Mo layer is 2 nm and that of the Si layers varies between 1 and 4 nm. The B4C layer thickness introduced at the Mo/Si and Si/Mo interfaces is 0.3 or 1 nm. It is shown that the reflectivity of the multilayers lowers with the decreasing silicon thickness. This is correlated to the diffuse character on the nanometer scale of the Mo/Si and Si/Mo interfaces as shown by secondary ion mass spectrometry, and the formation of silicides (MoSi2 and Mo5Si3) at these interfaces as evidenced by X-ray emission spectroscopy. As expected, the introduction of B4C diffusion barriers considerably improves the reflectivity coefficient in the soft X-ray range, due to thinner and more abrupt interfaces. [Copyright &y& Elsevier]

Abstract: We investigate on a Mo/Si multilayer interferential mirror (MIM) as a function of annealing at temperatures up to 600°C. The physicochemical state of the silicon atoms within the MIM is characterized by X-ray emission spectroscopy (XES). A thin silicide layer is detected at the interfaces of the as-prepared system, whose thickness increases upon annealing. Measurements of the reflecting power at 1.33nm show that both the reflectivity and the period markedly decrease as the annealing temperature increases, thus stressing on the interplay between the interface physico-chemical state and the optical properties. Our results shed light on the highest temperature regime, 600°C, where the MIM loses its periodic structure as the majority of the silicon atoms are involved in the MoSi2 compound. The diffusion coefficient is estimated from the evolution of the reflected intensity and the period. An activation energy of the diffusion process of 0.52eV is deduced. [Copyright &y& Elsevier]

The physico-chemical state of silicon atoms present in the HfO2/SiO2/Si system is studied by X-ray emission spectroscopy induced by electrons. From the analysis of the Si3p occupied valence states the very thin oxide interfacial layer is characterized. From the simulation of the spectra and the calculation of the emissive thicknesses, the silicon oxide thickness is determined to be one or two monolayers, depending on the sample. The presence of point defects at the interface is also suggested. [Copyright &y& Elsevier]

The influence of temperature and polarization of the substrate during the in situ treatment under argon plasma of silicon is studied. This treatment is performed before microwave plasma enhanced chemical vapour deposition of alumina. The transitory period preceding the introduction of the aluminium precursor is simulated by a 1.5 min oxygen plasma exposure of the substrate. The surface of the samples is analysed by electron-induced X-ray emission spectroscopy (EXES) to probe the physico-chemical environment around the silicon atoms, and by atomic force microscopy (AFM) to study the surface morphology. A thin superficial silica layer is evidenced, whose thickness is ranging from 0.8 to 1.8 nm, depending mostly on the temperature and subsequently on the polarization. Upon treatment the morphology of the surface is changed and the roughness is increased. Furthermore, AFM observations of substrates exposed to the aluminum precursor during 2 s are showing a columnar growth of the alumina film. [Copyright &y& Elsevier]

Electron-induced x-ray emission spectroscopy (EXES) associate with a semi-empirical electron scattering model is used to determine thicknesses between 2 and 21 nm of SiO[SUB2] films on Si. The small charging effect occurring upon electron irradiation is taken into account by introducing a retarding potential in the model. The results are in very close agreement with those obtained by spectroscopic ellipsometry and x-ray reflectometry. It is demonstrated that the EXES with its model is a well-suited method for the quantitative analysis of thin insulating films with an uncertainty lower than 5%. [ABSTRACT FROM AUTHOR]

Abstract: Aperiodic molybdenum/silicon (Mo/Si) multilayer designed as a broadband polarizer with reflectivity over a wide wavelength range of 13–30nm at a fixed incidence angle of 45° was developed by a numerical method. The multilayer was prepared using direct current magnetron sputtering. The reflectivity and polarizing properties were characterized using synchrotron radiation. In 13–30nm wavelength region, the measured s-reflectivity (R s ) with standard deviation is 13.5%±3.1%, p-reflectivity (R p ) with standard deviation is 1.4%±0.5%. The mean of polarization degree is 81.2%. This broadband multilayer polarizer can be used in extreme ultraviolet polarization measurements, and will greatly simplify experimental arrangements. [Copyright &y& Elsevier]

Abstract: A set of Mo/Si periodic multilayers is studied by non-destructive analysis methods. The thickness of the Si layers is 5nm while the thickness of the Mo layers changes from one multilayer to another, from 2 to 4nm. This enables us to probe the effect of the transition between the amorphous and crystalline state of the Mo layers near the interfaces with Si on the optical performances of the multilayers. This transition results in the variation of the refractive index (density variation) of the Mo layers, as observed by X-ray reflectivity (XRR) at a wavelength of 0.154nm. Combining X-ray emission spectroscopy (XES) and XRR, the parameters (composition, thickness and roughness) of the interfacial layers formed by the interaction between the Mo and Si layers are determined. However, these parameters do not evolve significantly as a function of the Mo thickness. It is observed by diffuse scattering at 1.33nm that the lateral correlation length of the roughness strongly decreases when the Mo thickness goes from 2 to 3nm. This is due to the development of Mo crystallites parallel to the multilayer surface. [Copyright &y& Elsevier]