The fluorine concentration of fluorinated amorphous carbon (a-C:F) thin films with a low dielectric constant was controlled using magnetron sputtering with hydrogen gas dilution into CF4 gas. The structural, optical and defect properties of these films were investigated by infrared (IR) absorption, x-ray photoelectron spectroscopy, ultraviolet visual spectroscopy and electron spin resonance as well as dielectric constant measurements. IR absorption spectra of the films with various fluorine concentrations prepared by hydrogen gas dilution showed no vibration modes between hydrogen and carbon atoms in CH, CH2, and CH3 configurations, suggesting that the hydrogen concentration of these films is less than a few at. %. Furthermore, the structural properties change at a fluorine concentration of approximately 50 at. %. However, the dielectric constant of 2.5 that is required for the interlayer materials for the next generation of ultralarge scale integrated devices remains unchanged at this fluorine concentration. Based on these results, the thermal stability of these a-C:F films is discussed briefly.

Thermal stability of fluorinated amorphous carbon (a-C:F) thin films with a low dielectric constant was investigated by electron spin resonance (ESR), infrared (IR) absorption, optical absorption, and x-ray photoelectron spectroscopy (XPS) as well as measurements of film thickness and dielectric constant. IR and XPS measurements suggested that the strength of the CF3 and CF2 bonding configurations against annealing are weaker than that of the CF bonding configuration. ESR measurements revealed that the dangling bond density decreased by one order of magnitude after annealing at 300 °C and increased after annealing at 400 °C. Furthermore, the g value and the linewidth of the ESR spectrum decreased with increasing annealing temperature. Based on these results, the changes in structure and defect configuration are discussed.

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Carbon nanotubes and fullerenes were synthesized by arc discharge in a He gas atmosphere under a high magnetic field up to 10 T. Morphology and the yield of these nanotubes were investigated by scanning electron microscopy and transmission electron microscopy (TEM). The yield and type of fullerenes were also evaluated by ultraviolet visual spectroscopy. TEM images revealed that thin collapsed nanotubes having larger curvature were synthesized under a high magnetic field, in particular at 10 T. Furthermore, the ratio of C70 to C60 concentration was found to vary depending on the magnitude of the magnetic field during arc discharge. Based on these results, the effects of magnetic field on the synthesis of carbon nanotubes and fullerenes are discussed.

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We have investigated the kinetics of light-induced defect (dangling bond) creation and annealing processes in a-Si:H containing a large amount of hydrogen at 300 K and 77 K using the ESR technique. We have obtained direct evidence for the light-induced annealing of dangling bonds at 300 K. A model, in which nonradiative recombination of electrons and holes at hydrogen-related dangling bonds is taken into account, is presented to interpret the experimental results.