Spectroscopic characterisation of novel materials for semiconductor device applications
Reid, Ian (2007) Spectroscopic characterisation of novel materials for semiconductor device applications. PhD thesis, Dublin City University.
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The thesis uses surface science techniques to characterise the chemical composition and electronic properties of a range of carbon containing materials which have application in advanced semiconductor fabrication. The initial focus was on investigating the properties ofcarbon-doped oxide (CDO) which is a low dielectric constant material and a leading candidate to replace silicon dioxide (SiOz) as an interlayer dielectric (ILD) in microprocessor fabrication. The work then progresses to determine the optimum experimental conditions required to etch thin films of this material, while retaining the chemical composition, in an industrial fluorocarbon-based plasma etching (FBPE) system. This study was preceded by an investigation of how the chemical composition of a thin fluorocarbon films which forms on a surface in the plasma etcher depends on the C4Fs/Ar/Oz gas feed ratios and the power levels used in the processing. These studies were benchmarked by undertaking baseline studies of the plasma processing of conventional Si02 inter layer dielectric material. The chemical composition of the fluorocarbon films and the CDO layers were analysed using X-ray photoelectron spectroscopy (XPS). Synchrotron radiation based x-ray absorption spectroscopy GAS) and x-ray emission spectroscopy (XES) as well as resonant soft X-ray emission spectroscopy (RSXE) have been used to provide information on the valence band and conduction band state of both the CDO layers and the fluorocarbon films. The final part of the thesis consists of the measurement of the electronic structure of thin films of the organic semiconductor tetraphenylporphyrin (TPP) and metal TPP. The carbon and nitrogen partial density of states for both the valence and conduction band electronic structure has been determined, as well as core level spectra. Good agreement was found between the experimental measurements of the valence and conduction bands, and the results of density functional theory calculations.
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