Plasma assisted deposition of thin carbon films from methane and the influence of the plasma parameters and additional gases

Aschentrup A, Szekeres A, Gesheva K, Hamelmann F, Heinzmann U, Brechling A. Plasma assisted deposition of thin carbon films from methane and the influence of the plasma parameters and additional gases. Vacuum 76. 2004;76(2-3):139-142

Plasma-assisted deposition of thin silicon oxide films in a remote PECVD reactor and characterization of films produced under different conditions

Hamelmann F, Aschentrup A, Brechling A, et al. Plasma-assisted deposition of thin silicon oxide films in a remote PECVD reactor and characterization of films produced under different conditions. Vacuum. 2004;75(4):307-312.Silicon oxide thin films have been deposited in plasma-assisted CVD process. With tetraethylorthosilcate (TEOS, Si(OC2H5)(4)) as precursor and an oxygen RF-plasma, thin films of 50-100 nm were deposited on silicon wafers. The deposition process was controlled in situ by monitoring the soft X-ray reflectivity of the growing layer. The influence of additional gases such as nitrogen and changes of the plasma conditions on the resulting films have been studied by analyzing the films with grazing incidence X-ray reflectometry, infrared spectroscopy, spectral ellipsometry and capacitance-voltage and current-voltage measurements were performed at different temperatures. (C) 2004 Elsevier Ltd. All rights reserved

Fabrication and characterization of EUV multilayer mirrors optimized for small spectral reflection bandwidth

Lim YC, Westermalbesloh T, Aschentrup A, et al. Fabrication and characterization of EUV multilayer mirrors optimized for small spectral reflection bandwidth. APPLIED PHYSICS A-MATERIALS SCIENCE & PROCESSING. 2001;72(1):121-124.Our aim was to produce EUV multilayer mirrors with a small spectral bandwidth DeltaE less than or equal to 3 eV at 70 eV peak energy using UHV electron beam evaporation by varying the thickness ratio (Gamma = d(Abs)/d(Sp) + d(Abs)) between the absorber layer and the bilayer. The deposition process was controlled by in situ soft X-ray reflectometry, and ion-beam polishing as well as substrate-heating methods were applied to reduce the interface roughness. The reflection properties of the Mo-Si multilayer mirrors prepared were characterized by hard and soft X-ray reflectometry and details of the multilayer structure were revealed from cross-sectional transmission electron microscopy

Determination of layer-thickness fluctuations in Mo/Si multilayers by cross-sectional HR-TEM and X-ray diffraction

Aschentrup A, Hachmann W, Westerwalbesloh T, Lim YC, Kleineberg U, Heinzmann U. Determination of layer-thickness fluctuations in Mo/Si multilayers by cross-sectional HR-TEM and X-ray diffraction. APPLIED PHYSICS A-MATERIALS SCIENCE & PROCESSING. 2003;77(5):607-611.We present a method of deriving single layer thickness fluctuations of Mo/Si EUV multilayers from cross-sectional high-resolution transmission electron microscopy micrographs. The obtained thickness values for each layer are used in a layer model to calculate the grazing-incidence X-ray reflectivity (GIXRR) and the corresponding at-wavelength-reflectivity curves. Comparison with XRR measurements shows the strong effect of thickness fluctuations on the intensity of the secondary Kiessig fringes and the main Bragg maxima. This model results in substantially better reflectivity simulations than the standard periodic four-layer model or the assumption of statistically distributed (random) thickness errors. Results for reflectivity curves at 13-nm wavelength are discussed in terms of peak reflectivity, peak shift and further changes in the shape of the reflectivity curve

Silicon oxide nanolayers for soft X-ray optics produced by plasma enhanced CVD

Hamelmann F, Aschentrup A, Schmalhorst J-M, et al. Silicon oxide nanolayers for soft X-ray optics produced by plasma enhanced CVD. JOURNAL DE PHYSIQUE IV. 2001;11(PR3):431-436.We have studied the suitability of Plasma Enhanced Chemical Vapor Deposition (PECVD) to produce ultrasmooth silicon oxide layers ranging in thickness from some nanometers to some 10 nm. A tight process control of the layer thickness, layer density and microroughness of the growing film is required. We deposited silicon oxide on silicon wafers, float glass and superpolished quartz substrates. In a remote plasma enhanced CVD process, we used tetraethylorthosilicate (TEOS, Si(OC2H5)(4)) as precursor. Films with a thickness of some 10 nm were produced at different deposition parameters and characterized by in-situ soft X-ray reflectivity, hard X-ray diffraction and auger electron spectroscopy. Best results could be found for the deposition using TEOS in oxygen plasma. In case Of SiO2 layers deposited on standard glass substrates signifcant roughness smoothing was obtained

Thermal behaviour of Co/Si/W/Si multilayers under rapid thermal annealing

Luby S, Jergel M, Anopchenko A, et al. Thermal behaviour of Co/Si/W/Si multilayers under rapid thermal annealing. APPLIED SURFACE SCIENCE. 1999;150(1-4):178-184.The e-beam deposited multilayers (MLS) were studied under rapid thermal annealing (RTA) between 250 degrees C and 1000 degrees C during 39 s. MLS with five Co/Si/W/Si periods, each 13.9 nm (MLS1) and 18 nm (MLS1) were deposited onto oxidized Si substrates. Samples were analyzed by X-ray diffraction, hard and soft X-ray reflectivity measurements and grazing incidence X-ray diffuse scattering. The MLS period, interface roughness and its lateral and vertical correlations were obtained by simulation of the hard X-ray reflectivity and diffuse scattering spectra. The MLS1 with thinner Co layers is more temperature resistant. However, its soft X-ray reflectivity is smaller. The results show that this is because of shorter lateral and vertical correlation lengths of the interface roughness which may considerably influence the X-ray reflectivity of multilayers, (C) 1999 Elsevier Science B.V. All rights reserved

Silicon oxide nanolayers for soft X-ray optics produced by plasma enhanced CVD

We have studied the suitability of Plasma Enhanced Chemical Vapor Deposition (PECVD) to produce ultrasmooth silicon oxide layers ranging in thickness from some nanometers to some 10 nm. A tight process control of the layer thickness, layer density and microroughness of the growing film is required. We deposited silicon oxide on silicon wafers, float glass and superpolished quartz substrates. In a remote plasma enhanced CVD process, we used tetraethylorthosilicate (TEOS, Si(OC2H5)4) as precursor. Films with a thickness of some 10 nm were produced at different deposition parameters and characterized by in-situ soft X-ray reflectivity, hard X-ray diffraction and auger electron spectroscopy. Best results could be found for the deposition using TEOS in oxygen plasma. In case of SiO2 layers deposited on standard glass substrates signifcant roughness smoothing was obtained

Plasma enhanced MOCVD of smooth nanometer-sized Metal/Silicon Single- and multilayer films

Hamelmann F, Haindl G, Aschentrup A, et al. Plasma enhanced MOCVD of smooth nanometer-sized Metal/Silicon Single- and multilayer films. In: Allendorf MD, Besman TM, eds. Chemical Vapor Deposition CVD XV, ECS Proc. PV. 2000: 131

Thin molybdenum oxide films produced by molybdenum pentacarbonyl 1-methylbutylisonitrile with plasma-assisted chemical vapor deposition

Hamelmann F, Brechling A, Aschentrup A, et al. Thin molybdenum oxide films produced by molybdenum pentacarbonyl 1-methylbutylisonitrile with plasma-assisted chemical vapor deposition. THIN SOLID FILMS. 2004;446(2):167-171.Molybdenum oxide thin films were prepared by plasma-enhanced chemical vapor deposition of molybdenum pentacarbonyl 1-methylbutylisonitrile. This precursor is an interesting alternative for the commonly used molybdenum hexacarbonyl, because the substance is liquid at room temperature, offers sufficient volatility and stability to air and water. The film growth was monitored in situ by a soft X-ray reflectivity measurement. The films were deposited with different plasma gases (hydrogen and oxygen) under different conditions and analysed by Auger electron spectroscopy, X-ray diffraction and spectral ellipsometry. (C) 2003 Elsevier B.V All rights reserved

Effect of substrate heating and ion beam polishing on the interface quality in Mo/Si multilayers - X-ray comparative study

Anopchenko A, Jergel M, Majkova E, et al. Effect of substrate heating and ion beam polishing on the interface quality in Mo/Si multilayers - X-ray comparative study. PHYSICA B-CONDENSED MATTER. 2001;305(1):14-20.Three periodic Mo/Si multilayers were prepared by electron-beam evaporation at different conditions. An in situ polishing of amorphous Si layers with Ar+ ions of 800 eV energy and substrate heating to 170 degreesC were used for the two of them which were designed as multilayer mirrors optimized for 13 nm wavelength at normal incidence (30 periods of nominally 6.9 nm). A third multilayer was deposited at room temperature with reduced Mo layer thicknesses and number of periods to suppress interface roughness buildup. The goal was a comparison of ion beam polishing and substrate heating in terms of the interface quality and evaluation of the merit of more sophisticated depositions. The interfaces were studied by specular X-ray reflectivity and interface diffuse scattering measured at Cu K-alpha1 wavelength. The interface morphology parameters are very close on ion beam polishing and substrate heating indicating a similar relaxation mechanism of the growing surface. The main difference is a larger thickness of the Mo5Si3 interlayers with substrate heating, which has practical implications for peak reflectivities. On the other hand, a slightly worse interface replication here is appealing for the applications where a good imaging contrast is of primary importance. At room temperature deposition, the interface roughness is nearly doubled at 3 times smaller number of multilayer periods. (C) 2001 Elsevier Science B.V. All rights reserved