Charge Trap - The Memory Guy Blog

3D NAND: Who Will Make It and When?

(The following is an update of a post that originally ran on 13 December 2013. It was republished in 2024 as a part of a series on The Memory Guy blog to honor the 3D NAND inventors who have received the 2024 FMS Lifetime Achievement Award.)

This series, originally run in 2013, has looked at 3D NAND technology in a good deal of technical depth. At that time, the last question to be answered centered around the players and the timing that the technology would Continue reading “3D NAND: Who Will Make It and When?”

How Do You Erase and Program 3D NAND?

(The following is an update of a post that originally ran on 29 November 2013. It was republished in 2024 as a part of a series to honor the 3D NAND inventors who have received the 2024 FMS Lifetime Achievement Award.)

Some of my readers have asked: “How is 3D NAND Continue reading “How Do You Erase and Program 3D NAND?”

An Alternative Kind of Vertical 3D NAND String

(The following is an update of a post that originally ran on 8 November 2013. It was republished in 2024 as a part of a series to honor the 3D NAND inventors who have received the 2024 FMS Lifetime Achievement Award.)

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 Continue reading “An Alternative Kind of Vertical 3D NAND String”

3D NAND: Making a Vertical String

(The following is an update of a post that originally ran on 1 November 2013. It was republished in 2024 as a part of a series to honor the 3D NAND inventors who have received the 2024 FMS Lifetime Achievement Award.)

Let’s look at how one form of 3D NAND is manufactured. For this post we will explore Continue reading “3D NAND: Making a Vertical String”

Videos Demystify MLC NAND Programming

What really happens in NAND flash during an MLC, TLC, or QLC write? Although there are lots of websites that explain that multilevel cells store four, or eight, or sixteen different voltage levels on a cell (for MLC, TLC, or QLC), they don’t spell out the process of putting those voltage levels onto the bit cell.

Fortunately, Vic Ye, Manager, NAND Flash Characterization at Yeestor Microelectronics Co., Ltd. in Shenzhen, China presented the programming process in a series of short videos at the Flash Memory Summit last August. The Memory Guy was fortunate enough to attend his presentation. Yeestor is a fabless semiconductor manufacturer that manufactures flash storage controllers for SSDs (PCIe & SATA) and flash cards (SD, UFS, eMMC, etc.)

Mr. Ye later gave me permission to share his videos and these are the foundation of this post. They’re brief (13 seconds to 1:10) so they won’t take much time to review. The videos were a part of his slide presentation titled: A Graphical Journey into 3D NAND Program Operations that can be downloaded from The Flash Memory Summit website by clicking the presentation title above and entering your e-mail address.

A multilevel flash bit cell has Continue reading “Videos Demystify MLC NAND Programming”

Samsung’s View on Charge Trap Flash

At 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”

Hynix and Spansion Join Forces

SK Hynix and Spansion have announced a strategic NAND alliance under which Hynix will serve as a foundry for low-density SLC NAND chips made for Spansion using Hynix’ advanced processing nodes.

These products, aimed at the embedded market, should serve to strengthen Spansion in a market in which the company thrives. In fact, Spansion expressed this very well in their press release, citing: “Spansion’s recognized customer support and commitment for longevity of supply, which is highly valued in the embedded market, where Spansion has established relationships.”

The new chips will be manufactured in “4x, 3x, and 2xnm” process technologies.

The companies have also agreed to cross-license their patent portfolios.

You may be asking yourself: “What does Hynix Continue reading “Hynix and Spansion Join Forces”