The new chloro(cyclopentadienyl)silanes Cp′SiHyCl3−y (Cp′=Me4EtC5, y=1: 1; Cp′=Me4C5H, y=1: 2; y=0: 3; Cp′=Me3C5H2, y=1: 4 and pentachloro(cyclopentadienyl)disilanes Cp′Si2Cl5 (Cp′=Me5C5 5, Me4EtC5 6, Me4C5H 7, Me3C5H2 8, Me3SiC5H4 9) are synthesized in good yields via metathesis reactions. Treatment of 1–9 with LiAlH4 leads under Cl–H exchange to the hydridosilyl compounds Cp′SiH3 (Cp′=Me4EtC5 10, Me4C5H 11, Me3C5H2 12) and to the hydridodisilanyl compounds Cp′Si2H5 (Cp′=Me5C5 13, Me4EtC5 14, Me4C5H 15, Me3C5H2 16, Me3SiC5H4 17). Complexes 1–17 are characterized by 1H, 13C, and 29Si-NMR spectroscopy, IR spectroscopy, mass spectrometry and CH-analysis. The structures of 6, 7 and 9 are determined by single-crystal X-ray diffraction analysis. Pyrolysis studies of the cyclopentadienylsilanes 10–12 and disilanes 13–17 show their suitability as precursors in the MOCVD process.

There is a strong demand for alternative precursors for Si CVD that do not have the problems of highly pyrophoric silanes. Me5C5Si2H5 is an easy to handle liquid precursor that shows promise for CVD of Si-containing films. The fragmentation process (see Figure) has been studied by in-situ mass spectrometry and the pronounced leaving group character results in no carbon incorporation.

Molybdenum oxide/silicon oxide and tungsten oxide/silicon oxide multilayer with 24 periods and a period thickness of 9.2 nm were fabricated with plasma-enhanced MOCVD. The layer thickness was controlled by an in situ soft X-ray reflectivity measurement. For the deposition of the SiO2 layers, a new silicon organic precursor, pentamethylcyclopentadienyldisilane (Me5C5Si2H5) was used in an O2 remote plasma process. The high quality of multilayer interfaces was observed by cross-section transmission electron microscopy (TEM), the interface Toughness wasmeasured by hard X-ray reflectivity and diffuse scattering at grazing incidence experiments to be about 0.1 nm. Auger electron spectroscopy (AES) gives the information, that the silicon oxide is practically carbon free, and the carbon content of the metal oxides is low (<5%).

W/Si multilayers with 14 double layers (double layer spacing d = 24 nm) were deposited on Si [1001 substrates with hot-filament metal organic chemical vapor deposition (MOCVD). The layer thickness and growth was controlled by an in-situ X-ray reflectivity measurement. Cyclopentadienyl substituted silanes (C5Me5)Si2H5 and (C5Me4H)SiH3 were used as silicon precursors, while W(CO)6 was used for the tungsten deposition. The resulting multilayers were characterized by cross-section transmission electron microscopy (XTEM) and sputter auger electron spectroscopy (AES). In addition, the fragmentation of the silicon precursors was studied by mass spectroscopy

W/Si multilayers with eight double layers (double layer spacing d=20 nm) were deposited on Si [100] substrates using hot-filament (or hot-wire) metal organic chemical vapor deposition (MOCVD). The process was performed in a stainless steel reactor with a tungsten filament at a temperature of 1000°C and a substrate temperature of 190°C. The film thickness and growth was controlled by an in situ soft X-ray reflectivity measurement. The multilayers were characterized by cross-section transmission electron microscopy (XTEM) and sputter auger electron spectroscopy (AES). The results are compared to W/Si bilayers, which were deposited without a hot-filament at higher substrate temperatures (500–670°C).

W/Si and Mo/Si multilayers with 20 periods (doublelayer spacing d = 24nm) were deposited on silicon substrates using (remote-) plasma-enhanced MOCVD. The substrate temperature was below 200°C, which is necessary to avoid interdiffusion of the layers. The layer thickness and growth was controlled by an in situ soft x-ray reflectivity measurement. The characterisation of the multilayers showed an excellent growth of the silicon layers, while the metal layers are rough with embedded crystallites.

Three different examples have shown that nanoporous alumina membranes serve as ideal templates for the formation of nanostructured materials and also as a support of those materials in composites. The unique properties of such membranes (transparency, chemical resistivity, thermal stability, adjustable pore sizes etc.) and the very simple mode of generating these composites are the benefits of using this inorganic template material.