From the current landscape of publicly available DRAM technologies, the industry is expected to perceive 3D DRAM as one of the solutions to the challenges faced by DRAM technology, marking it as a pivotal direction for the future memory market.

Is 3D DRAM similar to 3D NAND? How will the industry address technological bottlenecks such as size limitations? What are the strategies of major players in the field?

• Understanding 3D DRAM Technology

The circuitry of DRAM consists of a transistor and a capacitor, where the transistor is responsible for transmitting electrical currents to write or read information (bits), while the capacitor stores the bits.

DRAM finds wide application in modern digital electronic devices such as computers, graphics cards, portable devices, and gaming consoles, due to its low cost and high capacity memory.

The development of DRAM primarily focuses on increasing integration by reducing circuit line widths. However, as line widths reach the 10nm range, physical limitations such as capacitor current leakage and interference significantly increase.

To address these issues, the industry has introduced new materials and equipment like high dielectric constant (high-K) deposition materials and Extreme Ultraviolet (EUV) devices.

Nevertheless, from the perspective of chip manufacturers, miniaturizing the manufacturing of 10nm or more advanced chips remains a significant challenge in current technology research and development. Additionally, the competition for advanced processes, particularly at 2nm and below, has intensified recently.

In an era marked by continuous technological advancements, the semiconductor industry has turned its attention to the evolution of NAND technology. To overcome scaling limitations, transistors are transitioning from a planar to a 3D architecture, increasing the number of storage units per unit area. This concept of 3D DRAM architecture has entered the public sphere.

In traditional DRAM, transistors are integrated on a flat plane. However, in 3D DRAM, transistors are stacked into multiple layers, thereby dispersing the transistors. It is believed that adopting a 3D DRAM structure can widen the gaps between transistors, reducing leakage currents and interference.

From a theoretical perspective, 3D DRAM technology breaks the conventional paradigm of memory technology. It is a novel storage method that stacks storage cells above logic units, enabling higher capacities within a unit chip area.

In terms of differentiation, traditional DRAM requires complex operational processes for reading and writing data, whereas 3D DRAM can directly access and write data through vertically stacked storage units, significantly enhancing access speeds. The advantages of 3D DRAM not only include high capacity and fast data access but also low power consumption and high reliability, meeting various application needs.

In terms of application areas, the high speed and large capacity of 3D DRAM will help improve the efficiency and performance of high-performance computing. The compact size and large capacity of 3D DRAM make it an ideal memory solution for mobile devices. The large capacity and low power consumption characteristics of 3D DRAM can meet the real-time data processing and transmission requirements of the Internet of Things (IoT) field.

Furthermore, since the advent of the AI era with ChatGPT, AI applications have surged, and AI servers are expected to become a strong driving force for the long-term growth in storage demand.

Micron’s chief business officer previously stated in an interview with Reuter that a typical AI server has up to eight times the amount of DRAM and three times the amount of NAND that a normal server has.

• Continued Industry Focus on 3D DRAM

The DRAM market remains highly concentrated, currently dominated by key players such as Samsung Electronics, SK Hynix, and Micron Technology, collectively holding over 93% of the entire market share.

According to a report from TrendForce, as of the third quarter of 2023, Samsung leads the global market with a share of 38.9%, followed by SK Hynix (34.3%) and Micron Technology (22.8%).

Currently, 3D DRAM is in its early stages of development, with companies like Samsung actively joining the research and development battleground. The competition is intense as various players strive to lead in this rapidly growing market.

• Samsung: 4F2 DRAM

Since 2019, Samsung has been conducting research on 3D DRAM and announced the industry’s first 12-layer 3D-TSV (Through-Silicon Via) technology in October of the same year. In 2021, Samsung established a next-generation process development research team within its DS division, focusing on research in this field.

At the 2022 SAFE Forum, Samsung outlined the overall 3DIC journey of Samsung Foundry and indicated its readiness to address DRAM stacking issues with a logic-stacked chip, SAINT-D. The design aims to integrate eight HBM3 chips onto one massive interposer chip.

In May 2023, as per sources cited by “The Elec,” Samsung Electronics formed a development team within its semiconductor research center to mass-produce 4F2 structured DRAM.

The goal is reportedly to apply 4F2 to DRAM at 10nm processes or more advanced nodes, as DRAM cell scaling has reached its limit. The report suggests that if Samsung’s 4F2 DRAM storage unit structure research is successful, the chip die area can be reduced by around 30% compared to existing 6F2 DRAM storage unit structures without changing the node.

In October of the same year, at the “Memory Technology Day” event, Samsung Electronics announced its plans to introduce a new 3D structure in the next-generation 10-nanometer more advanced nodes DRAM, rather than the existing 2D planar structure. The aim of this project is to increase the production capacity of a chip by over 100G.

At the “VLSI Symposium” held in Japan last year, Samsung Electronics presented a paper containing research results on 3D DRAM and showcased detailed images of 3D DRAM as an actual semiconductor implementation.

According to a report by The Economic Times, Samsung Electronics recently announced the opening of a new R&D laboratory in Silicon Valley, USA, dedicated to the development of next-generation 3D DRAM.

The laboratory is operated under Silicon Valley’s Device Solutions America (DSA) and is responsible for overseeing Samsung’s semiconductor production in the United States, as well as focusing on the development of new generations of DRAM products.

• SK Hynix – Introducing IGZO as the Channel Material for Future DRAM

Per SK Hynix’s research, the IGZO channel is attracting attention to improve the refresh characteristics of DRAM.

Reportedly, IGZO thin film transistors have been used in the display industry for a long time due to their moderate carrier mobility, extremely low leakage current and substrate size scalability. It can be a candidate for a stackable channel material for future DRAM.

• NEO – 3D X-DRAM Offers 8x Density Boost

NEO Semiconductor, a US memory technology company, introduces its groundbreaking technology, 3D X-DRAM, aimed at overcoming the capacity limitations of DRAM.

3D X-DRAM features the first-ever array structure of DRAM units based on Floating Body Cell (FBC) technology, akin to 3D NAND. Similar to 3D NAND Flash, its logic involves stacking layers to increase memory capacity. The FBC technology in 3D NAND Flash enables the formation of a vertical structure with the addition of a layer mask, offering high yield, low cost, and a significant density boost.

According to Neo’s estimates, the 3D X-DRAM technology can achieve a density of 128 Gb across 230 layers, which is eight times the current density of DRAM. NEO proposes a target of an eightfold capacity increase every decade, aiming to achieve a capacity of 1Tb between 2030 and 2035, representing a 64-fold increase compared to the current core capacity of DRAM.

This expansion is intended to meet the growing demand for high-performance and large-capacity semiconductor storage, especially for AI applications like ChatGPT.

“3D X-DRAM will be the absolute future growth driver for the Semiconductor industry,” said Andy Hsu, Founder and CEO of NEO Semiconductor.

• Japanese Research Team: BBCube 3D Outperforms DDR5 by 30x

A research team at the Tokyo Institute of Technology in Japan has introduced a groundbreaking 3D DRAM stacking design technology called BBCube, which enables superior integration between processing units and DRAM.

The most significant aspect of BBCube 3D lies in achieving a three-dimensional connection between processing units and DRAM instead of the traditional two-dimensional linkages. The team employs an innovative stacking structure while using an innovative stacked structure in which the PU dies sit atop multiple layers of DRAM, all interconnected via through-silicon vias (TSVs).

The overall structure of BBCube 3D is compact, devoid of typical solder microbumps, and utilizes TSVs instead of longer wires, collectively contributing to achieving low parasitic capacitance and low resistance, thereby enhancing the electrical performance of the device in various aspects.

The research team evaluated the speed of the new architecture and compared it with two of the most advanced memory technologies, DDR5 and HBM2E. Researchers claim that BBCube 3D could potentially achieve a bandwidth of 1.6 terabytes per second, which is 30 times higher than DDR5 and 4 times higher than HBM2E.

Furthermore, due to features like low thermal resistance and low impedance in BBCube, potential thermal management and power issues associated with 3D integration could be mitigated. The new technology significantly improves bandwidth while consuming only 1/20 and 1/5 of the bit access energy compared to DDR5 and HBM2E, respectively.

• Conclusion

The evolution of DRAM technology from 1D to 2D and now to the diverse structures of 3D has offered the industry various solutions to address its challenges. However, optimizing and improving manufacturing costs, durability, and reliability remain significant challenges in advancing 3D DRAM technology. Due to the difficulties in developing new materials and physical limitations, the commercialization of 3D DRAM still requires some time.

Based on the current research progress, the industry is actively engaged in the development of 3D DRAM, which are still in the early stages. According to industry insiders, it is predicted that 3D DRAM will begin to emerge around 2025, with actual mass production becoming feasible after 2030.

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(Photo credit: Samsung)

Another breakthrough has emerged in flash memory layer technology! A recent report cited by tom’s Hardware has suggested that at the upcoming International Solid-State Circuits Conference (ISSCC) in February of this year, Samsung Electronics will unveil the next-generation V9 QLC NAND solution, pushing flash memory layer technology to 280 layers.

The Battle of Layers is Far from Over

Reportedly, Samsung’s V9 QLC boasts a storage density of 28.5Gb per square millimeter, achieving a maximum transfer rate of 3.2 Gbps. This surpasses the current leading QLC products (2.4 Gbps) and is poised to meet the requirements of future PCIe 6.0 solutions.

Additionally, the report further highlights that Samsung’s V9 QLC is considered the highest-density flash memory solution to date.

Before Samsung, major storage giants such as Micron and SK Hynix had already surpassed the 200-layer milestone. Micron reached 232 layers with a storage density of 19.5Gb per square millimeter, while SK Hynix achieved 238 layers with a storage density of 14.4Gb per square millimeter.

Still, 280 layers are not the end of the storage giants’ layer count competition; there will be breakthroughs with even higher layer counts in the future.

In August 2023, SK Hynix unveiled the world’s highest-layer 321-layer NAND flash memory samples, claimed to have become the industry’s first company developing NAND flash memory with over 300 layers, with plans for mass production by 2025.

Reportedly, SK Hynix’s 321-layer 1Tb TLC NAND achieves a 59% efficiency improvement compared to the previous generation 238-layer 512Gb. This is due to the ability to stack more units of data storage to higher levels, achieving greater storage capacity on the same chip, thereby increasing the output of chips per wafer unit.

On the other hand, Micron plans to introduce higher-layer products beyond the 232-layer milestone. Samsung, with ambitious plans, aims to stack V-NAND to over 1000 layers by 2030.

Kioxia and Western Digital, after showcasing their 218-layer technology in 2023 following the 162-layer milestone, also intend to develop 3D NAND products with over 300 layers in the future.

Amid Memory Market Rebound, What’s the Trend in NAND Flash Prices?

Amid economic headwinds and subdued demand in the consumer electronics market, the memory industry experienced a prolonged period of adjustment. It wasn’t until the fourth quarter of 2023 that the memory market began to rebound, leading to improved performances for related storage giants.

According to research conducted by TrendForce, a global market research firm, NAND Flash contract prices declined for four consecutive quarters starting from the third quarter of 2022, until they began to rise in the third quarter of 2023.

With a cautious outlook for market demand in 2024, the trend in NAND Flash prices will depend on the capacity utilization rates of suppliers.

TrendForce has projected a hike of 18-23% for NAND Flash contract prices, with a more moderated QoQ price increase of 3-8% for 2Q24. As the third quarter enters the traditional peak season, the quarterly price increase could potentially expand synchronously to 8-13%.

In 4Q24, the general price rally is anticipated to continue if suppliers maintain an effective strategy for controlling output. For NAND Flash products, their contract prices are forecasted to increase by 0-5% QoQ for 4Q24.

(Photo credit: Samsung)

Japanese telecommunications operator NTT is reportedly collaborating with American chipmaker Intel and other semiconductor manufacturers to research large-scale production of next-generation semiconductor technology, which involves significantly reducing power consumption using optical technology.

According to a report from Nikkei, SK Hynix is also set to participate in this initiative, expected to counter China through collaborative research and development strategies.

Meanwhile, the Japanese government will provide approximately JPY 45 billion in support. As cited by Nikkei quoting Japan’s Ministry of Economy, Trade, and Industry, Japan can lead the world in this technology as part of its strategy to revitalize the national semiconductor industry.

These companies are reportedly aiming to develop equipment manufacturing technology that integrates light with semiconductors and memory technology capable of storing data at Terabit-class speeds by the fiscal year 2027. Intel will provide technical development suggestions, aiming to reduce power consumption by 30-40% compared to conventional products.

As semiconductor scaling reaches physical limits, as per a report from TechNews, the industry is turning towards light. When combined with semiconductors, known as silicon photonics, it is expected to significantly reduce energy consumption. This technology is also seen as potentially game-changing for the semiconductor industry.

Signals received through optical communication is converted into electrical signals by specialized equipment, which are then transmitted to data center servers. Semiconductors within the servers then exchange electrical signals to process computations and memory. With the proliferation of AI and the need to process massive amounts of data, the demand for optical technology is anticipated to increase.

The integration of silicon photonics still presents numerous challenges, primarily concerning interface communication protocols. Consequently, synchronization in communication among semiconductor manufacturers is essential for the realization of silicon photonics technology.

Therefore, NTT aims to coordinate necessary technologies through collaboration with Intel and SK Hynix.

NTT holds a global leadership position in integrating optical and electronic technologies, having successfully pioneered the foundational technology of using light for transistor circuits. This achievement was published in the British scientific journal “Nature Photonics” in 2019, leading to the introduction of the IOWN (Innovative Optical and Wireless Network) fully optical network based on this technology.

(Photo credit: Intel)

Amid the AI trend, the significance of high-value-added DRAM represented by HBM continues to grow.

HBM (High Bandwidth Memory) is a type of graphics DDR memory that boasts advantages such as high bandwidth, high capacity, low latency, and low power consumption compared to traditional DRAM chips. It accelerates AI data processing speed and is particularly suitable for high-performance computing scenarios like ChatGPT, making it highly valued by memory giants in recent years.

Memory is also representing one of Korea’s pillar industries, and to seize the AI opportunity and drive the development of the memory industry, Korea has recently designated HBM as a national strategic technology.

The country will provide tax incentives to companies like Samsung Electronics. Small and medium-sized enterprises in Korea can enjoy up to a 40% to 50% reduction, while large enterprises like Samsung Electronics can benefit from a reduction of up to 30% to 40%.

Overview of HBM Development Progress Among Top Manufacturers

The HBM market is currently dominated by three major storage giants: Samsung, SK Hynix, and Micron. Since the introduction of the first silicon interposer HBM product in 2014, HBM technology has smoothly transitioned from HBM, HBM2, and HBM2E to HBM3 and HBM3e through iterative innovation.

According to research by TrendForce, the mainstream HBM in the market in 2023 is HBM2e. This includes specifications used in NVIDIA A100/A800, AMD MI200, and most CSPs’ self-developed acceleration chips. To meet the evolving demands of AI accelerator chips, various manufacturers are planning to launch new products like HBM3e in 2024, expecting HBM3 and HBM3e to become the market norm.

The progress of HBM3e, as outlined in the timeline below, shows that Micron provided its 8hi (24GB) samples to NVIDIA by the end of July, SK hynix in mid-August, and Samsung in early October.

As for the higher-spec HBM4, TrendForce expects its potential launch in 2026. With the push for higher computational performance, HBM4 is set to expand from the current 12-layer (12hi) to 16-layer (16hi) stacks, spurring demand for new hybrid bonding techniques. HBM4 12hi products are set for a 2026 launch, with 16hi models following in 2027.

Meeting Demand, Manufacturers Actively Expand HBM Production

As companies like NVIDIA and AMD continue to introduce high-performance GPU products, the three major manufacturers are actively planning the mass production of HBM with corresponding specifications.

Previously, media reports highlighted Samsung’s efforts to expand HBM production capacity by acquiring certain buildings and equipment within the Samsung Display’s Cheonan facility.

Samsung plans to establish a new packaging line at the Cheonan plant dedicated to large-scale HBM production. The company has already invested KRW 10.5 trillion in the acquisition of the mentioned assets and equipment, with an additional investment of KRW 700 billion to KRW 1 trillion.

Micron Technology’s Taichung Fab 4 in Taiwan was officially inaugurated in early November 2023. Micron stated that Taichung Fab 4 would integrate advanced probing and packaging testing functions to mass-produce HBM3e and other products, thereby meeting the increasing demand for various applications such as artificial intelligence, data centers, edge computing, and the cloud. The company plans to start shipping HBM3e in early 2024.

In its latest financial report, SK Hynix stated that in the DRAM sector in 2023, its main products DDR5 DRAM and HBM3 experienced revenue growth of over fourfold and fivefold, respectively, compared to the previous year.

At the same time, in response to the growing demand for high-performance DRAM, SK Hynix will smoothly carry out the mass production of HBM3e for AI applications and the research and development of HBM4.

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(Photo credit: SK Hynix)

NAND flash memory giants Kioxia and Western Digital (WD) were reported to be in negotiations with intentions to merge. However, the merger talks between Kioxia and WD were halted in October last year due to opposition from SK Hynix, the South Korean memory giant indirectly invested in Kioxia.

As per a report from Japanese media 47news, Kioxia has been making adjustments behind the scenes and is interested in restarting merger negotiations with WD. Kioxia’s major shareholder, Bain Capital, is reportedly in negotiations with SK Hynix.

It is reported that Kioxia is also exploring the possibility of cooperation with SK Hynix, but this may pose risks of violating anti-monopoly laws. If Kioxia and WD ultimately fail to merge, going public independently is also an option for Kioxia.

According to the report citing sources, SK Hynix is concerned that a merger between Kioxia and WD would weaken its influence over Kioxia. Therefore, SK Hynix is interested in participating in the integration to safeguard its influence.

On the other hand, WD has announced on October 30 last year that its board had approved a spin-off plan to separate its NAND flash memory division and establish a new company for independent listing, with operations expected to commence in the second half of 2024.

As per TrendForce’s  data for 3Q23, Samsung maintained its position as the top global NAND flash memory manufacturer, commanding a significant market share of 31.4%. Following closely, SK Group secured the second position with a 20.2% market share. Western Digital occupied the third position with a market share of 16.9%, while Japan’s Kioxia held a 14.5% market share.

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• [News] Kioxia and Western Digital Merger in Turmoil? Reports of SK Hynix Disapproval and a Possible SoftBank Collaboration
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(Photo credit: Kioxia)