A surface infrared spectroscopy study of reaction chemistry during silicon chemical vapor deposition processes

In chemical vapor deposition (CVD) processes, knowledge of how chemical species adsorb and dissociate on the substrates is both technologically and scientifically important. A fundamental understanding of the reaction mechanisms of precursors with the surfaces may serve to optimize a particular method of CVD, or help develop a new CVD process. Surface Infrared Spectroscopy (SIS) is a very powerful tool in the surface chemistry study on semiconductor surfaces; it provides information on the chemical nature of surfaces and adsorbates. Due to its high resolution, high sensitivity and strict selection rules, it is often possible to determine the structure of surface species and in turn derive detailed reaction mechanisms from the infrared data. SIS is often combined with other surface techniques, such as Scanning Tunneling Microscopy (STM) and X-Ray Photoelectron Spectroscopy (XPS) to provide a more complete picture of surface chemistry.;The reaction chemistry of molecular precursors (phosphine, tertiary butyl compounds and some boron-containing compounds) on the Si(001) surface has been investigated using SIS. Phosphine is found to adsorb both nondissociatively and dissociatively, depending on the coverage and flux during exposure. Infrared spectra also reveal the effect of surface phosphorus. Tertiary butyl phosphine and tertiary butyl chloride are found to give very different surface species upon adsorption and subsequent thermal dissociation on Si(100). Very different reaction mechanisms are proposed, based on their adsorption and thermal decomposition behavior. The implications of the different reaction mechanisms for the use of organic precursors for silicon CVD processing are discussed. Complex boron compounds were found to involve very different reaction intermediates from those observed in the reaction of diborane with Si(001). The implications of the different decomposition behaviors for the selection of boron precursors for silicon CVD processing are discussed.