SEMICONDUCTOR STORAGE DEVICE

According to one embodiment, a semiconductor storage device includes a first electrode and a second electrode spaced in a first direction and a phase change layer provided between the first electrode and the second electrode. The phase change layer comprises at least one of germanium (Ge), antimony (Sb), and tellurium (Te). The phase change layer is configured to be able to transition to a first state in which a volume ratio of an amorphous phase to a crystalline phase is a first ratio, a second state in which the volume ratio is a second ratio larger than the first ratio, and a third state in which the volume ratio is a third ratio larger than the second ratio.