SEMICONDUCTOR MEMORY DEVICE AND ITS MANUFACTURING METHOD

PROBLEM TO BE SOLVED: To obtain a semiconductor memory device having a structure by which the detachment of a phase-change film is prevented, thermal diffusion through plugs is prevented and additionally an interface film as a base of the phase-change film can be formed with an accurate thickness and stably, and to obtain its manufacturing method. SOLUTION: A tungsten plug WP1 is selectively formed by passing through an interlayer insulating film IF1. The other end of the tungsten plug WP1 is electrically connected with one of source-drain regions 14, 14 of a selection transistor Q1 through a barrier metal BM1. A copper plug CP1 is selectively formed by passing through the interlayer insulating film IF3 and a stopper film SF1. The other end of the copper plug CP1 is electrically connected with one end of the tungsten plug WP1 through a barrier metal BM2. The interface film 27 is directly formed at one end of the copper plug CP1 and a GST film 23 and an upper electrode 24 are stacked on the interface film 27. COPYRIGHT: (C)2008,JPO&INPIT