NAND Flash – The Memory Guy Blog

Is Micron Being Acquired?

The following is an excerpt of an Objective Analysis Alert sent to our clients 7/13/15.

A July 13 Wall Street Journal article disclosed that China’s state-owned Tsinghua Unigroup has bid to buy Micron Technology for $21 a share or $23 billion, which would make this the largest-ever Chinese takeover of a U.S. company.

Objective Analysis has been telling our clients for the past few years that either China or India would create a new DRAM/NAND manufacturing company, especially since memory chip makers have enjoyed a long period of profits, and this usually motivates outsiders to invest in new DRAM makers. We did not anticipate an acquisition.

Countries with heavy industry typically move into the semiconductor business during an extended upturn, and become DRAM suppliers since DRAM is an undifferentiated commodity. Commodities sell almost solely on price and success is based on little more than manufacturing strength. This is a business model that industrial economies understand.

In addition to Micron’s tangible assets, including Continue reading “Is Micron Being Acquired?”

What Memory Will Intel’s Purley Platform Use?

There has been quite a lot of interest over the past few days about the apparently-inadvertent disclosure by Intel of its server platform roadmap. Detailed coverage in The Platform showed a couple of slides with key memory information for the upcoming Purley server platform which will support the Xeon “Skylake” processor family. (A review of this post on 7/13/17 revealed that The Platform’s website has disappeared. The above link and the next one no longer work.)

One slide, titled: “Purley: Biggest Platform Advancement Since Nehalem” includes this post’s graphic, which tells of a memory with: “Up to 4x the capacity & lower cost than DRAM, and 500x faster than NAND.”

The Memory Guy puzzled a bit about what this might be. The only memory chip technology today with a cost structure lower than that of DRAM is NAND flash, and there is unlikely to be any technology within the leaked roadmap’s 2015-2017 time span that will change that. MRAM, ReRAM, PCM, FRAM, and other technologies can’t beat DRAM’s cost, and will probably take close to a decade to get to that point.

Since that’s the case, then what is this mystery memory? If we think of Continue reading “What Memory Will Intel’s Purley Platform Use?”

3D NAND: How do You Access the Control Gates?

One of the thornier problems in making 3D NAND is the job of connecting the peripheral logic (the row decoders) to all of those control gates that are on layers buried somewhere within the bit array. Remember that the control gates are the conductive sheets of polysilicon or tantalum nitride at various depths in the chip.

The problem boils down to this: You can’t run connections from each layer up or down the side of the chip to get to the CMOS circuits below. Instead you have to create a terrace structure to expose and connect to each layer.

These connections are made by etching a stair-step pattern into the layers and sinking Continue reading “3D NAND: How do You Access the Control Gates?”

An Alternative Kind of Vertical 3D NAND String

My prior 3D NAND post explained how Toshiba’s BiCS cell works, using a silicon nitride charge trap to substitute for a floating gate. This post will look at an alternative technology used by Samsung and Hynix which is illustrated in the first graphic, a diagram Samsung presented at a technical conference. This cell also uses a charge trap.

Let The Memory Guy warn you, if the process in my prior post seemed tricky, this one promises to put that one to shame!

Part of this stems from the use of a different kind of NAND bit cell. You can shrink flash cells smaller if you use a high-k gate dielectric (one with a high dielectric constant “k”) since it Continue reading “An Alternative Kind of Vertical 3D NAND String”

SanDisk & Toshiba Move to Next Process Node

SanDisk and Toshiba, in separate announcements, both today disclosed their next-generation process technology.

The companies introduced their new “1y” processing node that, according to SanDisk, produces 19nm x 19.5nm cell, versus the earlier “19nm” process (or “1x”) that used a 19nm x 26nm cell.

The graphic for this post (click to enlarge) was presented during SanDisk’s May 5th Analyst Day and compares the 24nm process to the 19 x 26nm process, moving to the 19 x 19nm process, and eventually to “1z” which neither company is yet revealing. After the 1z process SanDisk believes Continue reading “SanDisk & Toshiba Move to Next Process Node”

The End of Flash Scaling

Everyone knows that flash memory is about to hit its scaling limit – it’s right around the corner. We’re ready for it because it’s been right around the corner for more than a decade now. It’s so close we can taste it.

When will it happen?

One thing that is quite clear is that nobody knows when NAND flash will stop scaling. Everyone knows that it’s soon, but researchers continue to find ways to push the technology another couple of process nodes past where anyone thought it could possibly go, and they have been doing this since Continue reading “The End of Flash Scaling”

How Cheap is Flash?

The Memory Guy was a little surprised to see the advertisement in this post’s graphic. It was from an April 8 newspaper ad for Fry’s Electronics.

It’s a little early to see NAND selling for this little: The original price of $21.99 for a 32GB USB flash drive comes to $0.69/GB, and the price after the rebate of $16.99 means that the price per gigabyte of the flash is only $0.53!

At the time the lowest spot market pricing for MLC flash on the InSpectrum spot price website was $0.53, and $0.47 for TLC. According to DRAMeXchange MLC is selling for as little as $0.48.

That’s not a lot of margin for Patriot or Fry’s when you add in the cost of t Continue reading “How Cheap is Flash?”

MOSAID Samples 333GB/s HLNAND

MOSAID announced that the company is sampling a 333GB/s 512Gb HLNAND. According to MOSAID the devices packages: “16 industry standard 32Gb NAND Flash die with two HLNAND interface devices to achieve 333MB/s output over a single byte-wide HLNAND interface channel. Conventional NAND Flash MCP designs cannot stack more than four NAND dies without suffering from performance degradation, and would require two or more channels to deliver similar throughput.”

Think of this as a lower-cost NAND version of the Hybrid Memory Cube, which packages specialized DRAM using thousands of through-silicon vias (TSVs) atop a specialized interface. Both approaches use a custom logic chip to quickly move data across a point-to-point interface with the processor.

There were a couple of surprises with this announcement: First that it was made by MOSAID even though the company was acquired by Sterling Partners late last year. It would seem that the announcement would have borne the acquirer’s name.

Second, the press all remarked that the device was innovative since it was a 16-die NAND stack. This is not new! Samsung has been shipping 16-die NAND stacks for a couple of years now. Although it’s not an economical package, it’s in production.

MOSAID first introduced the HLNAND architecture in 2007. The Memory Guy has never fully understood how HLNAND fit in with the rest of MOSAID’s business. For the most part MOSAID has become a licensor and acquirer of IP, a departure from its origins as a chip design consultancy. It is unusual (but not unheard of) for such a company to champion an industry standard and to do much R&D on its own.

Either way, this is an impressive device with compelling throughput. Here’s a wish for MOSAID to successfully create a market for this technology.

New NAND Player: Macronix

Macronix, a company known for its leadership in mask ROMs and low-density NOR flash has just entered the NAND flash market. This adds a new player to a very small pool of competitors: Samsung, Toshiba, SanDisk, Hynix, Intel, and Micron.

The company’s first NAND products are SLC chips of two densities: 512Mb and 1Gb. Compare this to the offerings of the market’s other participants which range up to 256Gb. Spot price tracker InSpectrum doesn’t even track pricing of densities below 4Gb!

There still seems to be a good market for these low-density parts: According to WSTS Continue reading “New NAND Player: Macronix”

Top Ten Trends for NAND Flash

During the Flash Memory Summit in August three panelists were asked to tell what they thought would be the top ten trends for NAND flash in 2012.

The panelists were:

Troy Winslow, director of product and channel marketing for the Intel NAND group
Radoslav Danilak, SandForce founder and now CEO of StorCloud
Me

Here are mine:

Enterprise SSDs will be used in all data centers
There is still a lot of growth in NAND
Controllers will get more sophisticated
System software will be designed for NAND first
Tablet PCs will morph into newer devices
Not everyone can be a successful SSD supplier
NOR has a long future in code storage
NAND in PCs is a threat to DRAM, not HDDs
The death of flash is not imminent
SSDs in PCs will lose out to NAND + HDD

Over ten future posts I will elaborate on these. As I do I will add hot links to the list above to guide readers to these predictions. If any of the hot links are inactive, come back later and check again.

Many are detailed in reports on the Objective Analysis Reports page.