Nonvolatile semiconductor storage device and method of controlling and manufacturing the same

A method of controlling a nonvolatile semiconductor storage device provided with a cell group including a first memory cell and a second memory cell first directionally adjacent to the first memory cell, comprising:

• programming the first memory cell by:
• applying a first voltage to the first memory cell,
• applying a second voltage to the second memory cell,
• determining whether or not a threshold voltage of the first memory cell is greater than a target threshold voltage, and
• if determined not to be greater than the target threshold voltage, repeating the application of the second voltage to the second memory cell while gradually increasing the second voltage until the target threshold voltage is obtained.

A method of manufacturing a nonvolatile semiconductor storage device provided with a cell group including a first memory cell for data retention and a second memory cell for adjusting a threshold voltage of the first memory cell, comprising:

• preparing a semiconductor substrate;
• forming a gate insulating film above the semiconductor substrate;
• forming a floating gate electrode film above the gate insulating film;
• forming a plurality of mask patterns each used for forming the cell group and each including patterns that are spaced by a first width, the plurality of mask patterns each being spaced by a second width greater than the first width;
• etching the floating gate electrode film, the gate insulating film, and the semiconductor substrate to form a plurality of element isolation trenches using the mask pattern as a mask, thereby obtaining a first floating gate electrode of the first memory cell and a second floating gate electrode of the second memory cell located adjacent to each other by the first width;
• filling each of the element isolation trenches with an element isolation insulating film;
• forming an intergate insulating film above the first floating gate electrode and the second floating gate electrode;
• and forming a word line above the intergate insulating film.