NV Memory Selectors: Forming the Known Unknowns (Part 3)

Ron NealeIn this third part of a five-part series, contributor Ron Neale continues his analysis of selector technologies focusing the nature of the mystery of Forming and a number of the many unanswered questions.


From Part 2 of this series it is very clear that only a detailed and accurate description of threshold switching will allow an assessment of what might be possible during the act of Forming, when the threshold voltage of a selector or memory (if the latter is fabricated in its amorphous state) is reduced in some cases by a factor more than 30% from its as-fabricated value. The problem is that there have been numerous attempts to account for the threshold switching mechanism. In Part 3 of this series I will briefly explore some of threshold switching options and search for any which might be used to account for Forming.

Threshold switching: The key.

If understanding what is happening during threshold switching is the key to what might be possible during that single cycle of threshold switching associated with selector Forming, then there is a possible converse connotation: If we really understand what is happening Continue reading “NV Memory Selectors: Forming the Known Unknowns (Part 3)”

NV Stacked Memory Selectors: Forming the Known Unknowns (Part 2)

Ron NealeIn this second part of a five-part series contributor Ron Neale continues his analysis of selector technologies focusing the nature of the mystery of Forming and a number of the many unanswered questions.


Thin film selectors, or memory matrix isolation devices, based on chalcogenide glasses, would appear to be the devices of choice as non-volatile memory arrays move towards 3D stacked structures. Considerable progress has been made in finding selector compositions which can be doped to provide a suitable level of structural stability required for the NV memory array application.  These were discussed in the first part of this series.

However, there is one known unknown in relation to this type of selector and it is the need for Forming, with the unknown being the physical nature of the changes which occur within the device as a result of the Forming process and any implications those changes might have on reliability and performance. The outward manifestation of Forming is a change in threshold voltage from an initial value to some lower more constant operating value. Not just a minor threshold voltage change but a significant one, a reduction of the order 36% in some cases.

The diagram below illustrates Continue reading “NV Stacked Memory Selectors: Forming the Known Unknowns (Part 2)”

Emerging Memory Report Updated

Tom Coughlin and I are proud to announce that we have released an update of our popular emerging memory report.  This report, titled Emerging Memories Ramp Up, covers all leading emerging memory technologies from PCM and 3D XPoint through MRAM and ReRAM to less-known types like carbon nanotubes and polymeric FRAMs.

Anyone who makes or uses memory chips, or who is involved in this ecosystem as an investor or tool supplier needs to read and understand this study to prepare for one of the biggest changes in the history of the chip market.  The report’s wealth of information will allow companies to make strategic plans to gain a competitive edge.

The report’s forecast model has determined that the emerging memory market will grow to $20 billion by 2029 largely by displacing today’s less efficient Continue reading “Emerging Memory Report Updated”

Intel’s Optane DIMM Price Model

With Intel’s Cascade Lake rollout last month came with a co-introduction of 3D XPoint Memory in a DIMM form factor, the Optane DIMM that had been promised since the first introduction of 3D XPoint Memory in mid-2015.  A lot of benchmarks were provided to make the case for using Optane DIMMs (formally known as the Intel Optane DC Persistent Memory), but not much was said about the pricing, except for assertions that significant savings were possible when Optane was used to replace some of the DRAM in a large computing system.

So…  How much does it cost?  Well certain technical reports in resources like Anandtech probed sales channels to see what they could find, but The Memory Guy learned that the presentations Intel made to the press in advance of the Cascade Lake rollout contained not only prices for the three Optane DIMM densities (128, 256, & 512GB), but also provided the prices of the DRAM DIMMs that they were being compared against.  I’ll get to that in a moment, but first let’s wade through the fundamentals of Intel’s Optane pricing strategy to understand why Intel has needs to price it the way that it has.

In Objective Analysis’ report on 3D XPoint Memory, and in several presentations I have Continue reading “Intel’s Optane DIMM Price Model”

What’s Inside an Optane DIMM?

Part of Optane DIMM LogoWith the release of its Cascade Lake family of processors today (formally called the “2nd Generation Intel Xeon Scalable processor”) Intel disclosed more details about its Optane DIMM, which has been officially named the “Intel Optane DC Persistent Memory.”  This DIMM’s architecture is surprisingly similar to an SSD, even to the point of its having error correction and encryption!

The Memory Guy doesn’t generally cover SSDs, but I do cover DIMMs, so this is one of those posts that I could have put into either of my blogs: The Memory Guy or The SSD Guy.  I have decided to put it here with the hopes that it will be easier for members of the memory community to find.

The internal error correction, the encryption, and the fact that 3D XPoint Memory wears out and must use wear leveling, all cause the Optane DIMM’s critical timing path to be slower than the critical path in a DRAM DIMM, rendering the Optane DIMM unsuitable for code execution.  This, and the fact that XPoint writes are slower than its reads, all help to explain why an Optane DIMM is never used as the only memory in a system: there is always a DRAM alongside the Optane DIMM to provide faster Continue reading “What’s Inside an Optane DIMM?”

NV Stacked Memory: Selectors and Forming (Part 1)

Ron NealeIn this first post of a five-part series contributor Ron Neale analyzes selector technologies presented by CEA Leti at the 2018 IEDM conference last December.


At the close of last year the IEDM maintained its long-standing reputation for offering across-the-board the right focus at the right time on important and key parts of the electronic device discipline.   For those with an interest in the future of stacked or 3D NV-memory arrays there were a number of important papers and presentations on a variety of thin film memory selectors or matrix isolation devices (MIDs).

Important, because as the move towards stacked memory arrays for storage class memory (SCM) and persistent  memory (PM) applications gains momentum, the thin film selector may be the device which is key in determining the performance and reliability for a number of different types of NV memory arrays or even the very existence of that type of memory array.  One of the important and poorly understood variables in the mix is the selector forming voltage and the structural changes which lead from it to the operating device threshold voltage which, in my view needs a lot more by way of detailed understanding.

As the memory array moves into Continue reading “NV Stacked Memory: Selectors and Forming (Part 1)”

New Series – NV Memory Selectors: Forming the Known Unknowns

Photo of Ron Neale, Renowned Phase-Change Memory ExpertThe Memory Guy is pleased to announce a new series contributed by guest blogger and PCM expert Ron Neale.

The series will appear in five sections detailed below:

Part 1: The series starts by Continue reading “New Series – NV Memory Selectors: Forming the Known Unknowns”

Emerging Memories Today: Forecasting Emerging Memories

Emerging Memory ParadeReaders who have been following this series will note that The Memory Guy has so far described everything pertaining to emerging memory technologies except for the market outlook.  In this post I will share some key elements of our emerging memory forecast.

Since this is a simple blog post the forecast coverage is brief.  The detailed forecast appears in the report that is the basis of this blog post series: Emerging Memories Poised to Explode.

The first large-scale applications poised to replace today’s standard NOR flash with a new memory technology will be the embedded memories in CMOS logic chips that are processed on advanced process nodes (processes of 28nm and smaller.)  Many CMOS logic chips use NOR flash, especially microcontrollers (MCUs) which are found in a very broad range of applications.  The vast majority of MCUs, though, are uncomplicated and can therefore be economically produced on larger, older process nodes like 90nm and greater.

At tighter processes flashless versions of some MCUs already ship that can Continue reading “Emerging Memories Today: Forecasting Emerging Memories”

Where is Micron’s QuantX?

Micron Quantx LogoFor more than a year The Memory Guy has been fielding questions about Micron’s QuantX products.

First announced at the 2016 Flash Memory Summit, this brand name has been assigned to Micron SSDs and DIMMs that use the Intel/Micron 3D XPoint Memory.  Originally QuantX products were scheduled to ship in 2017, but Micron is currently projecting availability in 2019.  My clients wonder why there have been these delays, and why Micron is not more actively marketing this product.

The simple answer is that it doesn’t make financial sense for Micron to ship these products at this time.

Within two weeks of the first announcement of 3D XPoint Memory, at the 2015 Flash Memory Summit, I knew and explained that the technology would take two years or more to reach manufacturing cost parity with DRAM, even though Intel and Micron loudly proclaimed that it was ten times denser than DRAM.  This density advantage should eventually allow XPoint manufacturing costs to drop below DRAM costs, but any new technology, and even old technologies that are in low-volume production, suffer a decided scale disadvantage against DRAM, which sells close Continue reading “Where is Micron’s QuantX?”

Emerging Memories Today: Emerging Memory Companies

Emerging Memory ParadeMost memory industry participants view emerging memories as the eventual path of the business: There’s no doubt that today’s memory technologies will stop scaling, and that new memory technologies will need to replace today’s leading technologies both in the embedded and stand-alone spaces.  This includes DRAM, NAND flash, NOR flash, and SRAM.  Because this outlook is held by nearly everyone in the industry, all major memory manufacturers are investing in alternative memory technologies.  The leading players are researching multiple technologies at the same time.

Meanwhile, the industry outlook has allowed many university research projects and other similar efforts to gain funding to develop new memory types, spawning a large number of small single-technology companies tightly focused on one technology or another: ReRAM, MRAM, FRAM, and others, including such highly-differentiated technologies as carbon nanotubes and printable polymers.

In our Emerging Memory report Tom Coughlin and I did our Continue reading “Emerging Memories Today: Emerging Memory Companies”