Why Do We Need 3D NAND?

NAND Flash Capped Gate StructureA memory chip of a certain area costs about the same amount to produce, no matter how many bits it holds. Naturally, the more bits you can cram onto this chip, the cheaper the price per bit will be. Low cost is of the utmost importance in the world of memory.

Memory chip makers have shrunk the cost of a bit some nine orders of magnitude since the 1960s largely by shrinking the process, or “scaling” to increasingly tighter process geometries.

Flash has always been expected to reach a scaling limit. Over the past few generations technologists have developed Continue reading “Why Do We Need 3D NAND?”

What is 3D NAND? Why do we need it? How do they make it?

3D NANDIn August 2013 Samsung announced its V-NAND, the first production 3D NAND, kicking off a big change in the way that NAND flash will be manufactured.  This new technology raises a number of important questions:

  • What exactly is a 3D NAND?
  • Why does the industry need to go to a 3D topology?
  • How the heck do they make such a product?

To answer these questions I assembled a series of articles posted as weekly segments on The Memory Guy blog during the fourth quarter of 2013.  The different sections are listed below, with hot links to each section.

Each of these is a topic that is complex enough to warrant its own post, so for the nine Fridays I published a post to explain each one in depth.  I hope you find it engaging and informative.

Samsung’s View on Charge Trap Flash

Samsung's Cheese analogy for Charge Trap FlashAt the Flash Memory Summit yesterday ES Jung, PhD, EVP & GM for the Samsung R&D Center, explained the inner workings of Samsung’s new V-NAND vertical NAND flash technology.  I will shortly be writing a series to explain what a 3D NAND is since there is little on the web that gives clear details about the technology.

One key attribute of most 3D NAND approaches is the use of a charge trapping layer.  This has to do with the difficulty of manufacturing sideways floating gates.

Dr Jung delighted the show’s audience by explaining that a standard floating gate is like Continue reading “Samsung’s View on Charge Trap Flash”

Samsung Announces 3D NAND Production

Toshiba's BiCS 3D NAND 2007 diagramSamsung has announced production of its 3D NAND technology.  This approach, first introduced by Toshiba in 2007, allows NAND flash makers to achieve more bits per chip by building NAND strings, which normally run across the surface of the chip, as vertical stacks.

It’s a fascinating technology, since it harnesses exotic steps invented by DRAM makers in the 1990s to get over scaling problems in that technology.  At the time DRAM had to go vertical to follow Moore’s Law and there were two schools of vertical DRAM: Stacked Capacitor, and Trench Cell.  The stacked capacitor camp layered polysilicon and silicon dioxide into layers to form a vertical capacitor.  The trench camp etched a very narrow and deep hole into the silicon and lined it with the capacitor plates.  Both worked very well, but over time the trench makers have Continue reading “Samsung Announces 3D NAND Production”

Applied’s Take on 3D NAND

Applied Materials expects for 3D NAND to grow the etch & CVD markets by 50%Early this month I was invited to participate in Applied Materials’ (AMAT) Analyst Day.  The sessions were rich in data covering the markets that would profit the company over the next few years.

Naturally, The Memory Guy fixated on those presentations that dealt with memory.  When it came to the upcoming transition to 3D NAND, AMAT had a lot to say.

A later post will explain what 3D NAND actually is.  Suffice it to say that today’s approach to making NAND flash has nearly reached its limit, and the approach that manufacturers plan to use in the future involves making NAND strings that stand on their ends.  This has phenomenal implications on Continue reading “Applied’s Take on 3D NAND”