Investigations on aluminum tri-isopropoxide containing plasmas for the deposition of Al2O3
Résumé
Metal oxide films are widely used in a variety of products. Their properties make them interesting for a growing field of applications. Especially alumina is of high interest due to its hardness, chemical resistance, low conductivity and capacity as diffusion barrier. Therefore, Al2O3 is applied e.g. in solar cells, as erosion and corrosion resistant coating on cutting tools, for encapsulation of phosphor particles or for the production of OLEDs. Providing a homogenous high quality coating, CVD and especially plasma enhanced CVD processes (PECVD) are the favoured processes to deposit alumina on complex geometries. A suitable technique is the use of aluminum tri-isopropoxide (ATI) in process plasmas. Nevertheless, the processes taking place in that complex plasma are not well understood, yet. In this work aluminum tri-isopropoxide containing plasmas were investigated by using mass spectrometry and Fourier transform infrared spectroscopy (FTIR). The obtained results allow describing possible reaction paths referring to the fragmentation of monomeric ATI, finally leading to the formation of AlOx. Moreover, the absolute concentration and the degree of dissociation of the ATI molecules as well as the fragmentation efficiency and fragmentation rate have been calculated. Furthermore, polymerisation products were observed and quantitative information could partially be obtained, providing important information about the plasma chemistry.