Nonvolatile semiconductor memory and data programming/erasing method

A nonvolatile semiconductor memory, comprising:

• a semiconductor substrate;
• a first gate electrode formed on a surface of said semiconductor substrate through a first gate insulating film;
• a second gate electrode formed on said surface of said semiconductor substrate through a second gate insulating film and being adjacent to said first gate electrode through an insulating film;
• and
• a charge trapping film as an insulating film trapping charges that is formed at least in a trap region surrounded by said semiconductor substrate, said first gate electrod, and said second gate electrode,
• wherein said second gate electrode has an edge section facing said trap region, and
• wherein electrons are injected into said charge trapping film from said second gate electrode by electric field concentration on said edge section.

A data programming/erasing method for a nonvolatile semiconductor memory, said nonvolatile semiconductor memory comprising:

• a first gate electrode formed on a surface of a semiconductor substrate through a first gate insulating film;
• a second gate electrode formed on said surface of said semiconductor substrate through a second gate insulating film and being adjacent to said first gate electrode through an insulating film;
• a charge trapping film as an insulating film trapping charges that is formed at least in a trap region surrounded by said semiconductor substrate, said first gate electrode, and said second gate electrode;
• and
• a tunnel insulating film formed between said charge trapping film and said second gate electrode,
• the data programming/erasing method comprising:
• injecting electrons into said charge trapping film from said second gate electrode through said tunnel insulating film by Fowler-Nordheim tunneling.