DRAM having COB structure and its fabrication method

A DRAM having a COB structure according to the invention including a semiconductor substrate formed with a diffusion layer, a word line formed on the semiconductor substrate, an interlayer insulating film formed on the word line, a capacitor contact formed at the interlayer insulating film and connected to the diffusion layer, a bit line formed on the interlayer insulating film, a side wall insulating film formed on a side face of the bit line, a stack electrode formed by utilizing a side face of an insulating film selectively formed at a potion thereof directly above the bit line to be brought into contact with the capacitor contact, a capacitance insulating film formed on a surface of the stack electrode and a plate electrode formed on the capacitance insulating film.