Phase-change memory driven by a poly-Si MOS transistor enabling three-dimensional stacking

Abstract

We have been developing phase-change memory driven by a poly-Si MOS transistor to realize large-capacity non-volatile memory, namely post-flash memory. A thin-film phase-change layer on a Si channel makes it possible to reduce the reset current, and as a result, phase-change memory can be driven by a poly-Si MOS transistor, for which the on-current is smaller than the transistors on a Si substrate. A one-time dry etching process utilized for memory holes enables the realization of an ultra-low bit cost for phase-change memory. The reset operation of the developed phase-change memory at 45 µA and 30 ns corresponds to about a 1-GB/s programming throughput.