Semiconductor memory device using variable resistance element or phase-change element as memory device

A semiconductor memory device comprising:

• a first conductive line extending in a first direction;
• a second conductive line extending in a second direction crossing the first direction;
• a cell unit including a phase-change film and a rectifier element connected in series with each other between the first conductive line and the second conductive line;
• a silicon nitride film formed on an all side surface of the phase-change film in a plane in which the silicon nitride film and the phase-change film are cut in parallel with the first direction and the second direction;
• and
• a double-sidewall film including a silicon oxide film and the silicon nitride film formed on an all side surface of the rectifier element in a plane in which the double-sidewall film and the rectifier element are cut in parallel with the first direction and the second direction,
• wherein the silicon oxide film is in contact with the side surface of the rectifier element, and the silicon nitride film is in direct contact with the side surface of the phase-change film and is in direct contact with the silicon oxide film on the side surface of the rectifier element.