Infrared determination of interstitial oxygen behavior during epitaxial silicon growth on Czochralski substrates

Interstitial oxygen profile across an epitaxial silicon and Czochralski silicon interface has been studied using high-spatial-resolution Fourier transform infrared spectroscopy. Systematic transmission measurements performed on a transversal wafer cross section evidenced oxygen contamination of the epilayer. This was due to solid-state outdiffusion from the substrate occurring during epilayer deposition. Oxygen diffusivity values resulting from the experiments suggest a mechanism scarcely influenced by the interface. Oxygen contamination is strictly related to the type of dopant present in the substrate and not to that present in the epilayer. The oxygen contamination of the epilayer (significant in n-type substrate samples) could explain the structural defects often observed in epitaxial layers by different techniques.