▎ 摘　　要

NOVELTY - Memory device (21), comprises: a substrate (100); a first conductive layer (110) disposed over the substrate; a phase change layer (150) disposed over the first conductive layer; a selector layer (130) disposed between the phase change layer and the first conductive layer; and a second conductive layer disposed over the phase change layer, where at least one of the phase change layer and the selector layer has a narrow-middle profile. The first intermediate layer comprises tungsten, graphene, molybdenum disulfide, carbon, titanium, tantalum, tungsten nitride, titanium nitride and/or tantalum nitride. The heater comprises tungsten, titanium, tantalum, tungsten nitride, titanium nitride, and/or tantalum nitride. USE - The device is useful for electronic applications e.g. cell phones and personal computing devices. ADVANTAGE - The device: has several operating and engineering advantages including high speed, low power, non-volatility, high density, and low cost; is non-volatile and may be written into rapidly, e.g. within less than 50 nanoseconds; cells may have high density; and is compatible with complementary metal oxide semiconductor logic and can generally be produced at low cost compared to other types of memory cells. DETAILED DESCRIPTION - INDEPENDENT CLAIMS are also included for: (a) memory device; and (b) forming a memory device. DESCRIPTION OF DRAWING(S) - The figure shows cross-sectional view of the memory devices. Memory device (21) Substrate (100) First conductive layer (110) Selector layer (130) Phase change layer (150)