Adverse influences of organic contaminants on electronic devices have been studied and the results are reported. Contamination of silicon wafers by organic compounds during their manufacturing processes has been clearly demonstrated by a few surface analytical techniques. Silicon wafers were intentionally contaminated by one of the major contaminants, bis(2-ethylhexyl) phthalate; its incorporation into the silicon oxide layer during the thermal oxidation of silicon and its influences on device performances have been evaluated in detail by monitoring the breakdown voltages. During thermal oxidation of the contaminated silicon surface, the atomized carbon species produced from the pyrolysis of organic contaminants help grow the oxide thicker, expand the silicon oxide lattice, and degrade the silicon oxide, which was shown by transmission electron microscopy and secondary ion mass spectroscopy, and finally exert adverse influences on the device performance. (c) 2008 The Electrochemical Society.