Memory research

Numonyx and Intel have demonstrated a 64 Mb test chip that has the ability to stack or place multiple layers of PCM arrays within a single die, allowing memory devices to be built with greater capacity, lower power consumption and smaller.

The research program has been focusing on multi-layered or stacked PCM cell arrays and researchers have produced a vertically integrated memory cell - called PCMS (phase change memory and switch).

PCMS comprises one PCM element layered with a newly used ovonic threshold switch in a true cross point array. The ability to layer or stack arrays of PCMS provides the scalability to higher memory densities while maintaining the performance characteristics of PCM.

Memory cells are built by stacking a storage element and a selector, with several cells creating memory arrays. The researchers were able to deploy a thin film, two-terminal OTS as the selector, matching the physical and electrical properties for PCM scaling.

With the compatibility of thin-film PCMS, multiple layers of cross point memory arrays are now possible. Once integrated and embedded in a true cross point array, layered arrays are combined with CMOS circuits for decoding, sensing and logic functions.