Semiconductor device and method for manufacturing semiconductor device

A semiconductor device comprising:

• a silicon substrate;
• a tunnel insulating film provided on the silicon substrate;
• a floating gate electrode provided on the tunnel insulating film;
• a polycrystalline insulating film provided on the floating gate electrode, the polycrystalline insulating film having a high dielectric constant than silicon oxide, and the polycrystalline insulating film being made of crystal grains which are substantially monocrystalline in a film thickness direction;
• and
• a control gate electrode provided on the polycrystalline insulating film.

A semiconductor device comprising:

• a silicon substrate;
• a tunnel insulating film provided on the silicon substrate;
• a floating gate electrode provided on the tunnel insulating film;
• a polycrystalline insulating film provided on the floating gate electrode, the polycrystalline insulating film having a high dielectric constant than silicon oxide, and a size of crystal grains of the polycrystalline insulating film is larger in a film surface direction than in the film thickness direction;
• and
• a control gate electrode provided on the insulating film.