A process for fabricating an ONO floating-gate electrode in a two-bit EEPROM device includes the sequential formation of a first silicon oxide layer, a silicon nitride layer and a second silicon oxide layer using an in-situ deposition process in which the silicon nitride layer is not exposed to ambient atmosphere prior to the formation of the top oxide layer. To avoid exposure to ambient atmosphere, the first silicon oxide layer, the silicon nitride layer and the second silicon oxide layer are sequentially formed using either a PECVD or a SACVD process.