Plasma enhanced chemical vapour deposition of silica thin films

Abstract

Atmospheric pressure chemical vapour deposition is an industrially significant process for forming functional thin films. There is a great opportunity for increased scientific understanding with the aim of improving current processes and helping to formulate new ones. This work is concerned with developing a methodology to assist this ongoing concern. A combination of spectroscopic and chemometric techniques are used to investigate several chemical vapour deposition processes. The first investigation concerns the spatial concentration mapping of key by-products during the thermal chemical vapour deposition of tin oxide films through the use of near infra red laser diode spectroscopy. This novel two dimensional characterisation of the process has identified reaction hotspots within the process, and has identified the redundancy of part of the exhaust mechanism. Subsequently, there has been improvements to the head design, and the operation of the process.The main thrust of the investigations are focussed towards the use of chemometric methods, such as experimental design and principal components analysis, in conjunction with a suite of spectroscopic measurement techniques, to analyse the plasma enhanced chemical vapour deposition of silica films. This work has shown the importance of active oxygen species on the chemistry. It has also been shown that the film properties are highly dependant on oxygen concentration in the reactor, and hence active oxygen species forming in the plasma. The identification of by-products in the silica deposition process has also been carried out for the first time. Finally, this work also presents the first rigorous studies of a new precursor for silica deposition, dichlorodimethylsilane.EThOS - Electronic Theses Online ServiceGBUnited Kingdo