Quantitative determination of oxygen in silicon by combination of FTIR-spectroscopy, inert gas fusion analysis and secondary ion mass spectroscopy

Abstract

VLSI devices are almost exclusively fabricated on Czochralski (CZ) silicon containing high concentrations of interstitially dissolved oxygen ([Oi] ∼ 5×1017−1×1018 cm−3) which acts as getter for metallic impurities. Extensive analytical characterization is indispensable to study diffusion and precipitation of oxygen. This paper reports on the combination of fourier transform infrared absorption spectroscopy (FTIR), inert gas fusion analysis (IGFA) and secondary ion mass spectrometry (SIMS). It is shown that the combined use of these methods enables an extensive quantitative characterization of oxygen in silicon. The bulk oxygen content of high-resistivity material is routinely determined by FTIR and IGFA. In heavily doped substrates IR-absorption of free carriers is occurring. Thus only IGFA and SIMS can be applied.