Using scanning probe microscopy, we have modified a silicon surface and measured its current-voltage (I-V) characteristics. In the modified area, both an increase in film thickness and a decrease in current caused by field-induced oxidation (FIO) have been observed. The I-V characteristics of the FIO film shows a good fit to a Fowler-Nordheim (FN) tunneling current model. The barrier height determined by a FN plot shows a good agreement with that of conventional metal-oxide-semiconductor structure with thermal thick silicon oxide.