3D NAND: The future of flash memory

The quantity of data generated worldwide is growing at a staggering rate. By 2025, the collective sum of all global data will be a breathtaking 175 zettabytes (ZB)[1] - that’s 175 trillion gigabytes. In comparison, it was 33 zettabytes in 2018.

To put that in context, if you were to put 175ZB onto BluRay discs, you’d have a stack of discs that could get you to the moon 23 times.

This growth in data is driven by digitalization and the increasing role of technology in our everyday lives. 

The number of devices like smartphones and fitness trackers, connected to the Internet of Things (IoT), is growing exponentially. It’s predicted that around 29 billion devices will be connected to the IoT by 2022, a number that will only continue to rise.[2]

And those devices are expected to create around 90ZB of data by 2025 – just over half of the global total.[1]

In the face of this data explosion, the need for clever new data storage solutions is paramount. There is already a gap emerging between data generation and hard drive and flash production. 

Soon, we won’t have enough data storage to meet the growing levels of data we’re producing. By 2020, the gap between the amount of storage we need and the amount we actually have is predicted to be over 6ZB.[3]

The continued predicted growth of the IoT, as well as megatrends such as artificial intelligence and 5G, will only be possible if we can find innovative solutions to store the huge volumes of data that these trends both rely on and generate.

3D NAND is the latest generation of flash memory (also known as flash storage). 

Flash memory is used in enterprise server storage (data storage for large businesses) and networking technology, as well as in a wide range of consumer devices, including USB flash drives, smartphones, digital cameras, tablets, and laptops.

Before the introduction of 3D NAND technology, NAND flash memory options were all 2D or planar. However, we’re now reaching the physical limits of what can be achieved on a 2D plane.

Unlike 2D NAND where memory cells are crammed into a limited space on a chip, 3D NAND stacks the memory cells vertically on top of each other. Through cutting edge process technology, 3D NAND chips vertically connect the cell layers with channel holes (pathways through which data passes).

Just as skyscrapers allow a city’s population to increase within the same footprint, 3D NAND memory cell stacks increase storage capacity within the same horizontal space.

This new architecture delivers significantly more storage capacity – and at a lower cost per gigabyte.

But it’s not just about storage capacity. 3D NAND also enables data to process twice as fast, compared to earlier NAND chips and cuts power consumption by half.

For the everyday person, this means more data capacity, faster speeds, greater reliability and better power efficiency for our devices. We’ll be able to transfer files faster, store many more photos, analyze data in real time, and use robust applications without any lag, among many other things.

3D NAND technology is developing at a rapid pace. In 2015, 32 layers of memory cells were possible. Just four years later, we’re close to seeing a 96-layer structure launched. And by 2022, we expect 256-layer structures to be possible.

To help visualize this, the world’s tallest building – the Burj Khalifa in Dubai – is 828 meters high with a base of 140 meters. That’s an aspect ratio (AR) of about 6 to 1. Yet 3D NAND structures already work at an AR of around 60 to 1.

By the time we get to 256-layer structures, we’re talking about the equivalent of stacking 11 Burj Khalifas on top of one another. 

The transition from 2D to 3D NAND required significant changes to manufacturing processes for memory devices. A focus on process efficiency, materials innovations, and contamination controls will be crucial to achieving high volume manufacturing that meets performance, yield, and cost requirements.

Working in partnership with customers, our Semiconductor Solutions team is heavily involved in new developments to solve critical manufacturing challenges.

Our deposition, patterning materials and spin-on dielectric materials are already crucial to the processes involved in manufacturing 3D NAND chips. 

This includes our Spinfil^® spin-on dielectric material, for example, which is designed to fill staircase and deep trench respectively hole and simplify the manufacturing process of 3D NAND.

Meanwhile, our Advanced Lithography material KrF thick-film is used as an etching mask that enables production of 3D NAND staircases (which are integral to the chip’s structure).

“3D NAND is a perfect example of how we collaborate with our customers in the innovation process to bring groundbreaking, high-tech products to the market,” says Anand Nambiar, our Global Head of Semiconductor Solutions.

“This new technology, powered by our innovative materials and solutions, will enable a future where everything and everyone will be connected.” 

3D NAND is state-of-the-art, but manufacturers are already looking ahead to the next chapter in the flash memory story. News of the development were first released in late 2018.[4]

These new devices push peripheral circuitry underneath a CTF (charge trap flash) NAND array, thus saving more space on the chip and reducing production costs even further. 

With the race on to fill the predicted data storage gap of 6ZB by 2020, it seems likely that we won’t be waiting long for further developments.

^{[1] https://www.seagate.com/files/www-content/our-story/trends/files/idc-seagate-dataage-whitepaper.pdf
[2] https://www.ericsson.com/en/mobility-report/internet-of-things-forecast 
[3] https://www.sciencedirect.com/science/article/pii/S0167739X17312876
[4] http://www.businesskorea.co.kr/news/articleView.html?idxno=33316}