New chips will increase storage density without significant increase in bulk/weight/power

The 3D chipmaking clock has seen another tick.

I. Octa-die Design Offers Up To 128 GB per Package

Samsung Electronics Comp., Ltd. (KSC:005930) -- one of the largest chip fabricators worldwide -- announced this week that it had begun mass-production of (3D) Vertical NAND (V-NAND) flash memory.  The new memory will allow denser storage for SSDs, eventually trickling down into the smartphone/tablet component stream.

Samsung writes:

Samsung’s new V-NAND offers a 128 gigabit (Gb) density in a single chip, utilizing the company’s proprietary vertical cell structure based on 3D Charge Trap Flash (CTF) technology and vertical interconnect process technology to link the 3D cell array. By applying both of these technologies, Samsung’s 3D V-NAND is able to provide over twice the scaling of 20nm-class* planar NAND flash.

The new 3D V-NAND shows not only an increase of a minimum of 2X to a maximum 10X higher reliability, but also twice the write performance over conventional 10nm-class floating gate NAND flash memory.

Samsung 128 Gb

CTF stands for 3D Charge Trap Flash -- a silicon nitride based charge storage technology that represents a significant material improvement over traditional polycrystalline silicon-based charge storage (Floating Gate MOSFET).  The approach has multiple advantages including fewer defects, the ability to use smaller process sizes, and less manufacturing steps to form a node -- all of which cut costs -- plus improved reliability.

Samsung 128 Gb

The layers of silicon in the chip are connected by vertical interconnects.  Each chip in the stack packs between 128-Gigabits (Gb) and 1 Terabit (Tb) of storage. The chip is composed of 3 to 24 "cell layers".  The cell layers are believed to be composed at the unit level by 3-bit multi-level cell (3bMLC).  3bMLC chip dies are then wired up inside the package using through silicon via (TSV) style interconnects.

While Samsung does not officially reveal is node sizes unlike some other companies, here's a rough idea of Samsung's timeline for NAND production node dates and 3D (MLC, stacked) mass-production dates.

(Samsung) Node sizes:
The last generation (released in 2012) capped out at 64 GB (gigabytes), where as this generation caps out at 128 GB (with eight stacked dies), hence the claim about "over twice the scaling".  The die is also somewhat smaller -- an estimated 19 nm, versus 21 nm.

II. Chips are Likely Primarily Headed to SSDs

Interesting Samsung's NAND is going largely to SSD production, where its high density commands premium prices.  While Samsung ostensibly targets its stock at mobile chips, the Galaxy S IV was found to use Toshiba Corp. (TYO:6502) memory chips.

For now it seems Samsung's 3-bit levels per die/eight dies in stack (max) strategy, first launched commercially last year is still its state of the art approach, although die shrinks have allowed it to double the density per die.

Looking ahead Samsung will likely look to continue to increase per-die capacities with shrinks and may opt to bump the bit levels or stack count a bit, as the process matures.

For those new to flash, history, here's a quick guide to some early flash memory milestones -- some of which Samsung played a part in:
  • 1973: Dr. Fujio Masuoka files his first of many patents on floating gate (FG) based non-volative memory (NVM) (storage)
  • 1984: NOR FG storage is perfect and presented by Dr. Masuoka, now at Toshiba
  • 1985: Dr. Masuoka coins the term "flash" to describe FG-based NVM
  • 1986: Toshiba samples NOR flash
  • 1987: Dr. Masuoka tests NAND-gate based flash
  • 1988: First commercial NOR flash: Intel Corp. (INTC) 256 KB, $20 USD/chip
  • 1989: First commercial NAND flash: Toshiba recruits Samsung for fabrication, releases 256 KB NAND flash with longer life and faster erases
  • 1991: First flash storage format: PC Card is released
  • 1994: CompactFlash storage format is launched by SanDisk Corp. (SNDK)
  • 1995: MiniCard storage format is launched by Intel led coalition
  • 1995: SmartMedia storage format is launched
  • 1995: First flash hard drive: M-Systems and S-TEC, Inc. (STEC) release models
NAND = not and; NOR = not or (in boolean logic)

Source: Samsung [press release]

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