Does 3D XPoint memory use phase change memory (PCM) technology or not?
After IMTF co-chair Guy Blalock said XPoint uses a chalcogenide material, like Phase-Change Memory (PCM), your storage correspondent sent a mail to Intel and Micron saying:
“According to my understanding phase-change memory is a non-volatile, chalcogenide material exhibiting a bulk change in state (crystyalline<->amorphous) when appropriate electricity is applied, which changes its resistance level, which level then indicates a binary 1 or 0.”
“Previously Intel and Micron spokespeople have denied repeatedly that XPoint is a phase-change memory technology, while affirming that the non-volatile material exhibits a bulk change which affects its resistance level.”
“Now Guy Blalock says it is chalcogenide-based. In which case, if it walks like a duck, quacks like a duck, eats like a duck and swims like a duck then it's a duck, and 3D XPoint memory is a phase-change, chalcogenide material.”
“I’d be grateful if Micron could confirm this, or explain how and why XPoint, which is non-volatile, chalcogenide-based, and exhibits a bulk change which affects its resistance level, is not phase-change memory.”
In reply, a Micron spokesperson said: “3D XPoint technology is a new class of non-volatile memory invented by Intel and Micron that relies on resistance change of the bulk material to achieve non-volatility. Unlike Phase Change Memory, 3D XPoint technology uses a unique cross point architecture, enabling it to scale in ways that Phase Change Memory has not been able to accomplish.”
Let's point a textual microscope at this and see what it reveals, which we might find out by what is not said.
- 3D XPoint technology is a new class of non-volatile memory
- Invented by Intel and Micron
- That relies on resistance change of the bulk material to achieve non-volatility
- Unlike Phase Change Memory, 3D XPoint technology uses a unique cross point architecture
- Enabling it to scale in ways that Phase Change Memory has not been able to accomplish.
The first three bullet points re-iterate what has already been said.
The next two say that 3D XPoint uses a cross-point architecture to scale in ways that PCM has not been able to achieve.
The text does not say that XPoint is not phase change memory or that it is phase-change memory. It says that it is non-volatile memory used in a cross-point architecture.
The Micron spokesperson has not explained “how and why XPoint, which is non-volatile, chalcogenide-based, and exhibits a bulk change which affects its resistance level, is not phase-change memory.”
Alternatively the spokesperson has done, indirectly, and the only difference between existing phase change memory technologies and 3D XPoint is the cross-point architecture.
Indirectly supporting this view, the spokesperson has not said: “3D XPoint is not phase change memory.”
Our conclusion is that 3D XPoint uses phase change memory. Quod ergo demonstrandum - or we are dummies? ®