Nitridation process for fabricating an ONO floating-gate electrode in a two-bit EEPROM device

A process for fabricating a stacked-gate structure including an ONO floating-gate electrode in a two-bit EEPROM device comprising:

• providing a semiconductor substrate having a first bit-line oxide layer and a second bit-line oxide layer therein separated by a substrate surface region;
• forming the ONO floating-gate electrode on the substrate surface region comprising:
• sequentially forming a first silicon oxide layer on the substrate surface region, a silicon nitride layer overlying the first silicon oxide layer, and a second silicon oxide layer overlying the silicon nitride layer;
• and
• subjecting the second silicon oxide layer to a rapid thermal chemical vapor deposition process in a nitrogen-containing gas to form a nitridated silicon oxide layer, and to form said ONO floating-gate electrodes;
• and
• depositing a control gate electrode layer overlying the ONO floating gate electrode to form a stacked-gate structure on the substrate surface region.

A process for fabricating an ONO floating-gate electrode in a two-bit device comprising the steps of:

• providing a semiconductor substrate having a silicon surface region;
• depositing a bottom silicon oxide layer overlying the surface region;
• depositing a silicon nitride layer overlying the bottom silicon oxide layer;
• depositing a top silicon oxide layer overlying the silicon nitride layer by a first rapid thermal chemical vapor deposition process at a temperature from about 700° C. to about 800° C. using nitrous oxide and dichlorosilane;
• and
• subjecting the top silicon layer to a second rapid thermal chemical vapor deposition process in a nitrogen-containing gas ambient selected from the group consisting of ammonia, nitrogen oxide, and nitrous oxide to form a nitridated silicon oxide layer having a nitrogen concentration from about 0 wt. % to about 10 wt. % to form said ONO floating-gate electrode,
• wherein the second rapid thermal chemical vapor deposition process is carried out at a temperature from about 700° C. to about 1000° C.