Yesterday evening, Toshiba Memory America introduced new flash memory devices for embedded flash memory. These devices are available in in 128GB, 256GB and 512GB versions that feature the high read/write speeds and low power consumption. These features are increasingly in demand for designs such as mobile devices, smartphones, and virtual reality systems.
Let's take a quick look at the concept of embedded flash memory, the specification being utilized, and how other companies are approaching flash memory.
What Is Embedded Flash Memory?
Flash memory is characterized by its ability to retain digital data even when system power is completely shut off. The main disadvantage is that it is slower than RAM.
Embedded flash memory is just that: memory that is embedded within another chip, often a microcomputer or a system-on-a-chip (SoC). It can serve any of a number of memory-related purposes within that chip, and that memory typically is not directly accessible to other chips via its host’s interface pins.
Flash memory is also used in the solid-state drives (SSDs) that are beginning to replace hard drives, with the main advantage being that SSDs have no moving mechanical parts, making them inherently more ruggedized.
UFS Version 3.0 Specification
The UFS is a JEDEC standard, which stands for universal frame system, and the UFS Version 3.0, which Toshiba’s new memory devices adhere to, “is specifically tailored for mobile applications and computing systems requiring high performance and low power consumption.”
JEDEC, the Joint Electron Device Engineering Council, is a global semiconductor industry group with members from about 300 companies. It develops open standards for the microelectronics industry, with a present emphasis on standards for flash memory and mobile memory.
96-Layer BiCS FLASH 3D Flash Memory
Toshiba's technology involves stacking memory cells vertically within the chip; in this case, 96 layers deep.
This arrangement “offers higher density, higher endurance, higher performance, and better power efficiency", according to Toshiba Memory America’s Doug Wong. A key advantage is the ability to store as many as four bits per cell in a vertical architecture with cells stacked vertically rather than being spread out horizontally. This allows for savings in board real estate.
To read more about how Toshiba developed their 3D NAND flash memory, check out AAC's interview with Doug Wong from last year: The Rise of Toshiba’s New 3D NAND Flash Memory.
3D memory. Toshiba’s previous generation of 64-layer stacked memory. Image courtesy of Toshiba
The new Toshiba devices consist of the flash memory, itself, and a controller fit into an 11.5 x 13mm package. The controller performs error correction, wear leveling, logical-to-physical address translation, as well as bad-block management, which simplifies the ability of designers to employ these devices.
Toshiba will be sampling the 128GB units starting January 23, 2019. It is expected that the other two versions will start to follow in March of this year.
The 3D Flash Memory Landscape
Toshiba is not alone in layered flash memory, but it seems to be the only manufacturer that has announced a 96-layer device so far.
- Samsung uses its 64-layer 3D flash memory devices in its solid state drives.
- SK Hynix Semiconductor is already shipping a 72-layer device and is planning to sample a 96 layer unit in the second half of 2019.
- Intel and Micron announced production and shipment of a 64-layer 4 bits/cell flash memory in May of 2018. A 96-layer device is in the works.
- Yangtse Memory Technologies Company (YMTC) features its Xtacking architecture, whereby the memory and controller elements exist on separate wafers.
Image from YMTC
What would you like to learn about embedded flash memory? Let us know in the comments below.