Non-volatile semiconductor memory and process of fabricating the same

A non-volatile semiconductor memory comprising:

• at least one first gate electrode as a floating gate on a semiconductor substrate with intervention of a first insulating film as a tunnel oxide film;
• sidewall spacers on both sidewalls of the first gate electrode in a direction of a channel length;
• a bit line formed of an impurity diffusion region of a conductivity type different from the conductivity type of the semiconductor substrate in a surface layer of the semiconductor substrate by the side of the first gate electrode,
• wherein the bit line comprises a first bit line formed in self-alignment using the first gate electrode as a mask and a second bit line formed in self-alignment using the first gate electrode and the sidewall spacers as a mask;
• and
• wherein the semiconductor substrate is provided with a trench in a region adjacent to the sidewall spacer, and the second bit line is formed in a surface layer of the trench.

A non-volatile semiconductor memory comprising:

• at least one first gate electrode as a floating gate on a semiconductor substrate with intervention of a first insulating film as a tunnel oxide film;
• sidewall spacers on both sidewalls of the first gate electrode in a direction of a channel length;
• a bit line formed of an impurity diffusion region of a conductivity type different from the conductivity type of the semiconductor substrate in a surface layer of the semiconductor substrate by the side of the first gate electrode,
• wherein the bit line comprises a first bit line formed in self-alignment using the first gate electrode as a mask and a second bit line formed in self-alignment using the first gate electrode and the sidewall spacers as a mask;
• and
• wherein the second bit line is deeper than the first bit line.