A phase change memory device includes a bottom conductive line, a dielectric layer, a bottom memory layer, and a top electrode. The dielectric layer covers the bottom conductive line. The bottom memory layer is in the dielectric layer and is electrically connected to the bottom conductive line. The bottom memory layer includes a tapered portion and a neck portion. The tapered portion is over the bottom conductive line and is tapered toward the bottom conductive line. The neck portion is directly between the tapered portion and the bottom conductive line. The neck portion has a substantially constant width. The top electrode is over and electrically connected to the bottom memory layer.