Semiconductor memory device and method of manufacturing the same

A semiconductor memory device comprising:

• a substrate;
• isolation insulating films which are embedded in isolation trenches formed in the substrate, and each of which has an upper surface higher than a surface of the substrate;
• and
• a memory cell which is located between the isolation insulating films and formed on the substrate,
• the memory cell including:
• a tunnel insulating film which is formed on the substrate;
• a charge storage layer which is formed on the tunnel insulating film and formed of a conductor;
• an inter poly dielectric which is formed on the charge storage layer;
• and
• a control gate electrode which is formed on the inter poly dielectric,
• the charge storage layer including:
• a first part which is formed on the tunnel insulating film, and has an upper surface that is equal in level to the upper surfaces of the isolation insulating films, and a first width in a channel width direction;
• a second part which is formed above the first part, and has a second width that is less than the first width in the channel width direction;
• and
• a connecting part which connects the first part with the second part,
• wherein a width in the channel width direction of the connecting part continuously changes from the first width to the second width from a side facing the first part toward a side facing the second part.