With AI’s information growth, highly effective reminiscence is changing into all of the extra needed for next-gen computing. It’s 3D NAND that may assist this necessity with cryogenic tech. What’s its future, and who’s main the market?
NAND flash expertise has been the first resolution for low-cost and large-density information storage functions for a number of a long time, enabling the revolution of markets from USB drives to cellphones to servers. The non-volatile two-dimensional (2D) NAND flash reminiscence has been the workhorse of the storage trade, delivering elevated efficiency, reliability and decrease energy consumption at decrease value.
Nevertheless, the arrival of smartphones has triggered an exponential want for storage in gadgets in addition to cloud servers to retailer information from thousands and thousands of functions throughout billions of gadgets. Over time, user-generated content material has grown from high-definition (HD) pictures to four-kilobyte (4K) movies, demanding extra superior and high-capacity storage options. Excessive-quality streaming content material, together with music and movies, requires vital storage capability.
This demand will be met by the trade’s transfer to a three-dimensional (3D) construction, the place horizontal layers of reminiscence cells are stacked and linked utilizing tiny vertical channels to extend storage density. This method permits the trade to maintain tempo with Moore’s Legislation regardless of the challenges of constructing reminiscence cells smaller. With every subsequent technology from single-layer cell (SLC) to quad-level cell (QLC) flash, the variety of bits per cell saved doubling.
Three-dimensional NAND (3D NAND) flash reminiscence has turn into the dominant non-volatile reminiscence for the reason that cargo of Samsung’s second-generation 32-bit layer in 2014. Relying on the NAND distributors (Samsung, Western Digital, Toshiba, Micron, SK Hynix and others), variations within the 3D NAND construction exist and are identified by totally different names, corresponding to vertical-NAND flash (V-NAND flash) and bit in value scalable (BICS).
During the last decade, the bit density has elevated from one gigabit per sq. millimetre (1 GB/mm²) to a powerful 14.6 gigabits per sq. millimetre (14.6 GB/mm²). The continued development in computing for coaching and generative AI fashions in cloud and edge computing, together with high-quality user-generated content material by way of smartphone cameras, will drive a big want for sooner, harder capability storage for at the least the subsequent 20 years. AI smartphones, AI private computer systems (AI PCs), AI servers, autonomous automobiles and robotics will likely be key drivers for 3D NAND development.
Consequently, the general NAND flash reminiscence market is anticipated to greater than double to achieve $83 billion by 2036, up from $40 billion in 2023.
Breaking obstacles in 3D NAND scaling
With out main improvements in instruments corresponding to deposition and etch, the evolution will battle to enhance the fee effectivity of NAND flash storage merchandise. Rising the processing steps and time to allow the scaling roadmap will drive higher funding in extremely superior deposition and etch instruments, which may barely decelerate the storage roadmap.
To satisfy rising information calls for pushed by AI, reminiscence distributors are discovering smarter methods to pack extra bits into tighter areas with out sacrificing value or efficiency. The trade is actively exploring improvements in tools and manufacturing methods to deal with these challenges. Some main tools producers for 3D NAND manufacturing, corresponding to Lam Analysis, are working carefully with reminiscence distributors to co-optimise superior deposition and etch applied sciences. For instance, Lam’s proprietary cryogenic expertise enhances etch chemistry and polymer administration options, serving to to mitigate 3D NAND scaling challenges.
Cryogenic expertise: etching and course of
Initially developed within the Nineteen Eighties, cryogenic etching is re-emerging as a dry etching methodology. The etch course of is carried out at a low on-wafer temperature, sometimes under 0°C, with temperature management permitting for operation at even decrease temperatures. Cryogenic etching helps to extend the adsorption of reactive substances whereas limiting the lateral etch price. Leveraging low-temperature advantages and totally different plasma chemistry delivers elevated excessive facet ratio etch functionality, enhancing the etching price. Adopting novel chemistries through the low-temperature course of improves the circularity and sidewall roughness of the etched holes. This expertise additionally reduces the general environmental impression of the etching course of. Cryogenic expertise addresses the challenges of the normal high-aspect ratio (HAR) course of.
Challenges in scaling 3D NAND
NAND vertical stack scaling offers rise to challenges primarily in movie deposition and etch, in contrast to gadget scaling by way of characteristic dimension discount. To sample, isolate and join vertically built-in 3D reminiscence gadgets, tough high-aspect-ratio (HAR) etches are required. The facet ratio for a gap or trench is mostly outlined because the ratio of the depth to the width of the outlet or trench. Important processes in 3D NAND manufacturing embody final stack movie deposition, powerful facet ratio etching and phrase line metallisation. Discovering the steadiness between bit density, learn and write speeds, energy, reliability, and value is essential for functions. The method turns into extra advanced as extra layers are added to the construction, resulting in elevated capital expenditures. Because the variety of layers rises, it turns into more and more expensive so as to add extra storage capability.
Nevertheless, the method complexity and capital depth of 3D NAND manufacturing contributes to the difficulties fabs face by way of course of management, yield and value per bit.
NAND is a fancy expertise that presents vital manufacturing challenges, corresponding to HAR etch processes to allow tiny vertical channels, acquiring enough drive present between the reminiscence cells, logic design optimisation and wafer warpage.
The 3D NAND for future
Lam Analysis has developed this expertise over time and is a market chief in 3D NAND dielectric etching. With the introduction of cryogenic etching expertise in 2019, Lam’s put in base has grown to greater than 7500 chambers, with practically 1000 of those in manufacturing with cryogenic etch expertise. This robust put in base offers Lam the expertise of etching greater than 5 million wafers utilizing cryogenic etch expertise.
The most recent innovation, Lam Cryo™ 3.0, leverages the advantages of utilising scalable, excessive energy and ion vitality confined plasma reactors, distinctive pulsed plasma expertise, and temperatures as little as -60°C to etch with tight profile management effectively. It allows deeper etching with out compromising the characteristic form. The repeatability of a extremely exact, predictable etching course of helps NAND suppliers obtain constant output throughout manufacturing.
