NAND EEPROM with perpendicular sets of air gaps and method for manufacturing NAND EEPROM with perpendicular sets of air gaps

摘要

According to one embodiment, a part of a buried insulating film buried in a trench is removed; accordingly, an air gap is formed between adjacent floating gate electrodes in a word line direction, and the air gap is formed continuously along the trench in a manner of sinking below a control gate electrode.

主权项

1. A nonvolatile semiconductor memory device including memory cells comprising:
a semiconductor substrate; a covered insulating film in a trench extending in a first direction, the trench dividing the semiconductor substrate into active regions adjacent to each other in a second direction crossing the first direction, control gate electrodes extending in the second direction; a select gate electrode extending in the second direction and adjacent to one of the control gate electrodes; charge storage layers disposed between the control gate electrodes and the active regions, each one of the charge storage layers being provided for each one of the memory cells; a select gate transistor disposed between one of the memory cells and a bit line, the select gate transistor having the select gate electrode; and a gap provided between the adjacent charge storage layers in the second direction and extending continuously in the first direction, the gap being formed in the trench above the covered insulating film, extending beneath the select gate electrode, the gap terminating at a point directly beneath the select gate electrode; wherein the covered insulating film exists in the trench below a part of the select gate electrode so as to line the portion of the gap extending beneath the select gate electrode.