Metrology of very thin silicon epitaxial films using spectroscopic ellipsometry

Non-destructive silicon epitaxial film thickness measurements have been performed using spectroscopic ellipsometry (SE) in the visible to near infrared range. The epitaxial films were grown by CVD at 700 - 900 degrees C. It is shown that SE can simultaneously determine the epitaxial film thickness, the native oxide thickness, and the substrate dopant concentration. The epitaxial film thicknesses measured by SE are in excellent agreement with results of secondary ion mass spectrometry (SIMS). The dopant concentrations measured by SE also agree well with SIMS results for n-type substrates, but are consistently higher than SIMS values for p-type substrates. This study shows that spectroscopic ellipsometry could be used in semiconductor manufacturing environments as a viable non-destructive technique for sub-0.5 mu m silicon epitaxial film thickness measurement.