A big reason why pretty much all of the analysts agree it must be a flavor of PCM is because of this:IMFT arranged the material in a crosspoint architecture, which is a common alignment for memory, denoting a chessboard-style series of bitlines and wordlines. There are many different uses for crosspoint architecture, so IMFT merely added some marketing magic to an established architecture naming convention to come up with its 3D XPoint moniker.
right from the horse's mouth.Guy Blalock, the co-CEO of IMFT (from the Micron side), narrowed it down when he commented earlier this year at an event hosted by the SEMI trade group that 3D XPoint uses a chalcogenide material and an Ovonyx switch. Intel had a joint venture with Ovonyx and has licensed its technology in the past, but Micron purchased the firm for $1.3 billion in 2012 from Energy Conversion Devices (ECD). Ovonyx specializes in proprietary PCM technology (Phase-Change Memory).