Semiconductor device, nonvolatile semiconductor storage apparatus using the device, and manufacture method of the device

A nonvolatile semiconductor memory device comprising.

• a plurality of buried bit lines arranged in a semiconductor substrate,
• a plurality of word lines on said semiconductor substrate arranged to intersect the buried bit lines;
• and
• a plurality of said semiconductor devices which areis disposed at respective intersections of said buried bit lines and said word lines, each of said semiconductor devices includes:
• a first gate insulating film on a semiconductor substrate,
• an isolating gate electrode on said first gate insulating film,
• an isolating insulating film on the top surface of said isolating gate electrode and a side surface of said isolating gate electrode,
• a floating gate on said isolating insulating film,
• a second gate insulating film on said floating gate,
• a control gate on said second gate insulating film;
• and
• a source region and a drain region in said semiconductor substrate on opposite sides of said floating gate;
• wherein said floating gate comprises a first floating gate portion which is on said first gate insulating film and is adjacent to said isolating gate electrode through a part of said isolating insulating film on said side surface of said isolating gate electrode and a second floating gate portion which is on said first floating gate portion and on a part of said isolating insulating film on said top surface of said isolating gate electrode.

A manufacture method of a semiconductor device comprising:

• forming an first gate insulating film on a semiconductor substrate,
• forming an isolating gate electrode on said first gate insulating film,
• forming an isolating insulating film on the top surface of said isolating gate, electrode and a side surface of said isolating gate electrode,
• forming a floating gate on said isolating insulating film,
• forming a second gate insulating film on said floating gate;
• and
• forming a control gate on said second gate insulating film;
• wherein said floating gate comprises a first floating gate portion which is on said first gate insulating film and is adjacent to said isolating gate electrode through a part of said isolating insulating film on said side surface of said isolating gate electrode and a second floating gate portion which is on said first floating gate and on a part of said isolating insulating film on said top surface of said isolating gate electrode.