Semiconductor memory device

A semiconductor memory device comprising:

• a substrate;
• a first electrode extending in a first direction parallel to a surface of the substrate and having a first surface and a second surface, the first surface being spread in the first direction and a second direction crossing the first direction, the second direction being perpendicular to the substrate, and the second surface being spread in the first direction and the second direction, having a periphery connected to the first surface, and being provided to extend inward in a third direction with respect to the first surface, the third direction being parallel to the substrate and crossing the first direction;
• a second electrode extending in the first direction and having a third surface and a fourth surface, the third surface being spaced from the first electrode in a fourth direction opposite to the third direction, and spreading in the first direction and the second direction, the fourth surface being opposed to the second surface and spreading in the first direction and the second direction, having a periphery connected to the third surface, and being provided to extend inward in the fourth direction with respect to the third surface;
• a first signal line provided between the second surface and the fourth surface and extending in the second direction;
• a first charge storage film provided between the first signal line and the first electrode, the first charge storage film including first parts provided at both ends of the first charge storage film in the first direction and a second part located between the first parts, the second part being provided to protrude in the third direction toward the second surface with respect to the first parts;
• and
• a second charge storage film provided between the first signal line and the second electrode, the second charge storage film including third parts provided at both ends of the second charge storage film in the first direction and a fourth part located between the third parts, the fourth part being provided to protrude in the fourth direction toward the fourth surface with respect to the third parts,
• a distance along the third direction between the second surface and the fourth surface being larger than a distance along the third direction between the first surface and the third surface,
• in a cross section passing through the first charge storage film and the second charge storage film and being parallel to the surface of the substrate, the first signal line having a contour formed from a fifth part opposed to the second part, a sixth part opposed to the fourth part, a seventh part connected to one end of the fifth part and one end of the sixth part, the seventh part being provided in the first direction, and an eighth part connected to the other end of the fifth part and the other end of the sixth part, the eighth part being provided in a direction opposite to the first direction,
• the seventh part including a portion having a different curvature from a vicinity of the one end of the fifth part or a vicinity of the one end of the sixth part,
• the eighth part including a portion having a different curvature from a vicinity of the other end of the fifth part or a vicinity of the other end of the sixth part, wherein the first signal line has a first distance along the third direction from the fifth part to the sixth part and a second distance along the first direction from the seventh part to the eighth part, the first distance being smaller than the second distance.