In this study, we use in situ Fourier transform infrared (FTIR) spectroscopy on a carbon-doped silicon oxide (SiOCH) to determine the origins of its lower breakdown strength (compared to Si0(2)) and the precursors of dielectric breakdown. While subjecting the SiOCH film to externally applied electric fields, the FTIR spectra are recorded. Changes in peak area ratios and intensities are determined and correlated to field-induced perturbation of chemical bonds in SiOCH. This is a potentially powerful technique which provides new insights into the dielectric degradation and breakdown phenomena. (c) 2005.