SanDisk’s Amazing 512GB SD Card

SanDisk's 512GB SD CardSanDisk has introduced an SD Card with a whopping 512 gigabytes of storage.  Noting that SD Card capacities have increased by 1,000 times over the past ten years, from 512MB to 512GB, the company says that this product is aimed at professional HD videographers (who can justify its $800 price) allowing them to shoot Raw-format footage without shutting their cameras off, which could potentially allow them to miss a magic moment.

To The Memory Guy this represents an amazing piece of packaging technology.  Let’s see why:

In 2003 SanDisk’s 512MB card contained Continue reading “SanDisk’s Amazing 512GB SD Card”

Making 3D NAND Flash – Animated Video

The good people at Coventor have graciously allowed me to post their video of the Pipe-Shaped BiCS 3D NAND flash process onto The Memory Guy blog site.  Click the image to see it play out.

Coventor tells me that they are the leading Continue reading “Making 3D NAND Flash – Animated Video”

Why NAND is So Difficult to Scale

ASML chart chowing the lithography used for 4X, 3X, 2X, and 1Xnm planar NAND and 3D NANDNAND flash is the process leader in memory technology, and this puts it in a very challenging position: It must ramp to high volume production using techniques that have never been tried before.

The graphic for this post (click to enlarge), supplied by ASML, the semiconductor industry’s leading lithography tool supplier, illustrates the challenge of migrating from one process node to the next.  Across the bottom, on the X-axis, are representative process nodes ranging from “2D-45”, or two-dimensional (planar) 45nm NAND, to “3D-5x”, or three-dimensional 5xnm NAND.  Below these numbers are the year of volume production.

The vertical axis, labeled “Tolerance” represents the minimum Continue reading “Why NAND is So Difficult to Scale”

3D NAND: Who Will Make It and When?

SK hynix 3D NAND Cross SectionThis series has looked at 3D NAND technology in a good deal of technical depth.  The last question to be answered centers around the players and the timing of the technology.  A lot has been said about the technology and its necessity.  Will everyone be making 3D NAND?  When will this big transition occur?

This post will provide an update as of its publication (13 December 2013) to show each company’s current status, to the best of The Memory Guy’s understanding.  Readers may want to refer back to the earlier posts in this series, as well as to a June 2013 Nikkei TechON article that gives a good review of the 3D NAND alternatives that have been presented at various technical conferences.

Let’s start with Samsung, the largest producer of NAND flash today.  Just prior to Memcon 2013 last Continue reading “3D NAND: Who Will Make It and When?”

3D NAND’s Impact on the Equipment Market

Costs to Migrate to Next Lithography Node - Applied Materials (click to enlarge)A very unusual side effect of the move to 3D NAND will be the impact on the equipment market.  3D NAND takes the pressure off of lithographic steps and focuses more attention on deposition and etch.  The reason for going to 3D is that it provides a path to higher density memories without requiring lithographic shrinks.

This sounds like bad news for stepper makers like ASML, Canon, and Nikon while it should be a boon to deposition and etch equipment makers like Applied Materials, Tokyo Electron, and Lam Research.

In its summer 2013 V-NAND announcement, Samsung explained that it would be Continue reading “3D NAND’s Impact on the Equipment Market”

How Do You Erase and Program 3D NAND?

How FN Tunneling WorksSome of my readers have asked: “How is 3D NAND programmed and erased?  Is it any different from planar NAND?”

In a word: No.

(Before I get too far into this allow me to admit that The Memory Guy doesn’t understand quantum physics, so I will be presenting this only to the depth that I understand it.  There will be no band-gap diagrams or equations to wrestle with.)

Both 3D NAND and planar NAND use Fowler Nordheim Tunneling (FN) to both program and erase.  This differs from NOR flash which programs bits using Continue reading “How Do You Erase and Program 3D NAND?”

The Father of Flash Memory

Dr. Fujio Masuoka, the inventor of NAND and NOR flash memoryAt the Flash Memory Summit in August I had the honor of awarding Fujio Masuoka, the inventor of both NAND and NOR flash, the Flash Memory Summit Lifetime Achievement Award.  This award is given to the giants of the flash memory industry to acknowledge their contributions.

Dr. Masuoka first described NOR flash at the 1984 International Electron Device Meeting (IEDM) in San Francisco, and NAND flash at the same venue in 1987.  His paper “A new flash EEPROM cell using triple polysilicon technology” introduced a technology that is now used everywhere.

The award has also been given to Intel’s Flash team who brought the first commercial products to the market, and SanDisk co-founder Eli Harari, for devising a way to manufacture a floating gate.

David Schwaderer made a video of the presentation and posted it HERE.  Have a watch!

3D NAND: Benefits of Charge Traps over Floating Gates

Real California Cheese SealA prior post in this series (3D NAND: Making a Vertical String) discussed the difficulties of successfully manufacturing a charge trap flash bit.  Still, Spansion, and now other flash makers, have determined to take this route.  Why is that?

In Spansion’s case, a charge trap was a means of doubling the bit capacity of its products.  It was an inexpensive alternative to standard MLC flash.  To date this strategy has worked very well.

As mentioned in that earlier post, 3D NAND uses a charge trap because it’s extremely difficult to create features, like a floating gate, sideways – lithography works from the top down.  A charge trap, when used to replace a floating gate, doesn’t need to be patterned, since the Continue reading “3D NAND: Benefits of Charge Traps over Floating Gates”

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

Samsung's TCAT NAND Flash Wordline COnnectionsOne 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

Samsung's TCAT 3D NAND flashMy 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”