This disclosure is directed to a phase change semiconductor device and a manufacturing method thereof, comprising: forming an insulating layer on a substrate and a metal layer on the insulating layer; forming a via hole penetrating from the metal layer to the insulating layer; forming a phase change material layer on the metal layer and the via hole to at least fill up the via hole; and performing a planarization process, wherein after forming the metal layer and before forming the via hole, or after forming the via hole and before forming the phase change material layer, or after forming the phase change material layer and before the planarization process, subjecting the metal layer to an annealing treatment to form a metallic compound layer at an interface between the metal layer and the insulating layer. Adhesion between the phase change material layer and the insulating layer can be improved.