Highly-scalable novel access device based on Mixed Ionic Electronic conduction (MIEC) materials for high density phase change memory (PCM) arrays

Memory Select Devices

“…A so-called mixed ionic electronic conduction (MIEC) device is developed as select devices for PCM [64][65][66][67]. The device is made from Cu-containing MIEC materials sandwiched between an inert top electrode (TE; e.g., TiN, W) and a bottom electrode (BE).…”

“…Symmetrical diode-like I-V characteristics can be achieved with two inert electrodes. Large fraction of mobile Cu + enables high current density exceeding tens of MA/cm 2 [64]. For example, a 40 nm MIEC device is able to provide a current >200 μA, that is, a current density >15 MA/cm 2 .…”

“…The device selection capability of MIEC for large array is characterized by the voltage margin (V m ) between the positive and negative voltages measured at certain current level (e.g., 10 nA). It was shown that V m increases with decreasing device size [64]. Endurance above 10 8 cycles has been demonstrated on MIEC devices in small arrays [65].…”

Phase change memory

“…These devices are fabricated on a Si substrate and are called (front-end-of-line) FEOL devices. Most recently, a novel non-silicon device [41], which can be integrated with the PCM between two metal layers in the BEOL was demonstrated. The invention of such a BEOL device has led to revolutionary progress in non-volatile memory research, making stackable multi-layer memory array feasible.…”

“…Although a polysilicon diode was used in write-once anti-fuse memory technology, it is difficult to obtain the high-current drive capability needed for PCM [59]. As described in subsection 2.2, high-performance non-silicon devices based on mixed ionic electronic conduction have been demonstrated [41]. Combined with a 2-4-bit MLC, multi-layer stackable memory will provide the most attractive density, and, possibly, a cost advantage over 4-bit MLC flash.…”