Nonvolatile semiconductor memory device and manufacturing method thereof

A non-volatile semiconductor memory device comprising:

• a doped substrate;
• a first conductor layer formed on said substrate, including a plurality of portions each constituting a respective floating gate for a corresponding memory cell;
• a second conductor layer formed on said substrate and covering said first conductor layer, including a plurality of portions each constituting a respective control gate for a corresponding memory cell;
• each said control gate covers a corresponding floating gate of the same memory cell;
• a third conductor layer formed on said substrate and having the structure of a side wall spacer along one side wall of the twofold structure of the first and second conductor layers, including a plurality of portions each constituting a select gate for a memory cell;
• each said select gate being positioned along one side wall of the twofold structure of the floating gate and control gate of the same memory cell;
• said first, second, and third conductors are insulated from each other in the memory cell regions, and said second and third conductors are connected in an area in between memory cells.