Scalable 3-D vertical chain-cell-type phase-change memory with 4F2 poly-Si diodes

A three-dimensional (3-D) vertical chain-cell-type phase-change memory (VCCPCM) for next-generation large-capacity storage was developed. The VCCPCM features formation of memory holes in multi-layered stacked gates by using a single mask and a memory array without a selection transistor. As a result of this configuration, the number of process steps for fabricating the VCCPCM is reduced. The excellent scalability of the VCCPCM´s new phase-change material makes it possible to reduce the cell size beyond the scaling limit of flash memory. In addition, a poly-silicon selection diode makes it possible to reduce the cell factor to 4F². Consequently, relative cost of the VCCPCM compared to 3-D flash memory is reduced to 0.2.