Semiconductor device and method of forming the same

An apparatus comprising:

• a plurality of bit lines elongating in parallel in a first direction;
• and
• a plurality of multilayer structures, each of the multilayer structures comprising one of the bit lines and a first insulating film covering the top and side surfaces of each of the bit lines;
• wherein each of the multilayer structures comprises a taper-shaped segment on an upper portion thereof, and a distance between upper portions of adjacent multilayer structures is greater than a distance between lower portions thereof.

A method comprising:

• forming a plurality of first wirings elongating in parallel in a first direction on a substrate;
• forming a conductive film and a first insulating film in order above the first wirings and the substrate;
• etching the conductive film and the first insulating film with a mask to form a plurality of first multilayer structures including the conductive film and the first insulating film and elongating in parallel in a second direction different from the first direction;
• forming a second insulating film and a third insulating film on each side surface of the first multilayer structures to form a plurality of second multilayer structures, each of the second multilayer structures including the first multilayer structure, the second insulating films and the third insulating film;
• forming a fourth insulating film between the adjacent second multilayer structures;
• etching back the fourth insulating film to expose the upper surface and the upper side surface of the second multilayer structure;
• and
• isotropic etching on the first insulating film, the second insulating film, and the third insulating film to form a taper-shaped segment on an upper portion of the second multilayer structure.