Paving the way for greater storage capacity: 3D NAND Flash Memory
With file sizes getting larger and larger nowadays, NAND flash memory technology has been a major contributor in meeting in fulfilling these rising data storage demands. In this article, we will discuss the role of NAND flash memory, how 3D NAND is a major upgrade, and how NAND will further evolve.
Flash memory
3D NAND is a type of flash memory, which is the main storage technology used in storage devices such as SSDs (Solid-state-drives) and USB flash drives.
Memory vs storage
Although flash memory contains the term “memory” in its name, flash memory is actually used for data storage, instead of RAM (Random Access Memory) operations. When the term memory is mentioned, manufacturers are usually referring to DRAM (Dynamic Random Access Memory)-based DDR3, DDR4 modules, etc. Despite the similarities, memory and data storage have very different applications.
DRAM temporarily preserves data for quick access on a running system. It is a type of volatile memory, which means the system loses data when powered off. It is not designed to store data long-term. In contrast, flash memory stores data even when powered off. This makes it a type of non-volatile memory (NVM). For this reason, the term “storage” is a more suitable moniker for non-volatile memory-based storage devices such as SSDs, flash drives, etc.
Flash memory is particularly effective for storage because it does not rely on mechanical parts to handle data. Unlike Hard Disk Drives (HDDs) which rely on mechanical arms to magnetically read and write data over a rotating disk, flash memory utilizes integrated circuits to store data. As such, flash memory can read data around 10x faster and write data 20x faster than a standard HDD.
NAND flash in a nutshell
The predominant type of flash memory used is NAND (NOT-AND) flash. It is named as such because its utilizes transistors that closely resemble a “NOT-AND” logic gate transistor and it uses a binary system to store data.
In binary, a system of “1's” and “0's” are used to represent information. These “1's” and “0's” are known as bits and stringing bits together in different patterns can express a multitude of different values. These values are then processed by devices as bits of data. A modern computer can process a trillion bits or more, handling a significant amount of data.
NAND flash memory utilizes floating transistor gates to store the binary values. An open gate would represent “1” and a closed gate would represent “0”. When the storage device is reading data, it sends a current that checks whether these gates are open or closed. If the gate is open, the current will pass through. If the gate is closed, it will not pass through.
The computer can interpret these set of binary values and data sequences to output the correct functions. It then writes or deletes data based off these values.
The emergence of 3D NAND
Although NAND flash has been an indispensable storage technology for the greater part of two decades, manufacturers were starting to run into bottlenecks for storage density and limitations on storage scaling. NAND (also known as planar NAND or 2D NAND) is a two-dimensional solution, which means the flash memory cells are placed horizontally, side-by-side.
Drawbacks of planar NAND
Traditionally, the way to improve storage density was to reduce the space between each transistor. At a certain point, however, signal interference between side-by-side cells would start disrupting data flow and heavily diminishing data integrity. Simply increasing additional flash memory cells would also inflate manufacturing costs.
3D stacking
The solution to addressing storage scaling limitations is the introduction of 3D NAND or V-NAND (Vertical NAND). As its name suggests, 3D NAND uses stacking to build additional flash memory cells into the storage device. This is achieved by converting NAND cell strings (which were originally flat) into a U-shaped NAND string. The U-shaped NAND strings are then flipped vertically so that engineers could start building upwards instead of strictly sideways. With the ability to build both horizontally and vertically, manufacturers could take advantage of previously unused space.
3D NAND Performance and Roadmap
3D NAND is a vast improvement over NAND in terms of performance, durability, and power consumption. 3D NAND delivers read and write times that are up to 2x faster than a traditional NAND solution. It also offers up to 10x the durability of standard NAND while consuming half the power. Even as a newer technology, 3D NAND offers a greater value proposition as the price per bit is substantially lower than standard NAND. This is in part because the lithography costs for shrinking planar NAND wafers is much more expensive than the relatively straightforward design of V-NAND.
232-layer solution in development
Further improvements to the 3D NAND architecture are on the horizon. Currently, the leading consumer V-NAND technology can stack up to 128 layers of flash memory cells. Manufacturers have already announced the introduction of a whopping 232-layer solution. The next generation solution promises significantly higher read/write bandwidth and bits per cell. These features are designed to address key data storage needs for next generation applications.
Axiom can help with your storage needs:
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Sources
https://ieeexplore.ieee.org/document/7870331
https://newatlas.com/samsung-v-nand-flash-chip-ssd/28655/
https://www.techspot.com/news/84905-samsung-developing-industry-first-160-layer-nand-flash.html
https://www.pcmag.com/news/micron-offers-worlds-first-232-layer-3d-nand-flash-memory