NAND, 280 layers
在今年的ISSCC上，三星希望推出迄今为止数据密度最高的新型NAND 闪存。 据了解，三星届时将会分享一篇题为《A 280-Layer 1Tb 4b/cell 3D-NAND Flash Memory with a 28.5Gb/mm² Areal Density and a 3.2GB/s High-Speed IO Rate》的演讲，披露其下一代V9闪存。
As the title suggests, Samsung has developed a new generation of QLC NAND flash memory with 4 bits per cell, which is said to have an extremely high area density of 28.5 Gbits per square millimeter. This will obviously replace the current leader in this area, YMTC, with a 232-layer QLC NAND capacity of 19.8 Gbit/mm². From this data, it seems that even the high-density TLC-NAND of more than 300 layers and 20.0 Gbit/mm² announced by SK hynix, as well as Intel's first PLC-NAND of 5 bits per cell and 23.3 Gbit/mm², do not remember the density of Samsung's new memory.
According to a 2022 report by Samsung, Samsung is basically fully committed to QLC development. As TLC flash architecture begins to push the limits of raw storage capacity (just like SLC and MLC before it), QLC represents the future for SSD manufacturers who want to continue to push the limits of mainstream consumer SSD capacity. It may even make its way to enterprise-class SSDs in the future.
V9 is just the next step in Samsung's QLC roadmap. Future generations should be faster than V9 and can eventually compete directly with today's upcoming TLC flash architecture in terms of raw performance.
The V9 isn't slow either, with Samsung's V9 QLC reportedly having a maximum transfer rate of 3.2 Gbps. This is much faster than its upcoming QLC-based product, which only offers 2.4 Gbps. Speed has been a fundamental issue for QLC in the past, and Samsung's new V9 NAND flash shows that it has come a long way in solving this problem. The V9 has a speed of 3.2 Gbps (per chip), which should be more than enough for a PCIe SSD. Of course, it remains to be seen how well it will perform in practice.
What is not clear is how performance scales when writing directly in QLC mode. All current QLC SSDs use pSLC caching, which has a capacity of up to 25% of the total usable capacity, with significantly improved performance. Depending on the NAND, once the cache is full, we typically see write speeds drop to 100~300 MB/s.
If the performance is good enough, Samsung's new QLC-based flash memory will be available later this year and could fundamentally change the consumer SSD landscape. QLC may still not be able to service high-performance SSDs, such as those that support PCIe 5.0 transfer speeds, but it should be a good fit for lower-tier PCIe drives. With a storage density lead of nearly 50%, we can expect any new Samsung hard drive with the new V9 QLC flash memory to offer competitive value and potentially have the best price per gigabyte in the industry.
Depending on market demand, Samsung may even offer V9 QLC M.2 hard drives with capacities of more than 8TB, which is currently the highest capacity among consumer M.2 hard drives. Samsung may even launch a single-sided 8TB hard drive.
In recent years, Samsung has repeatedly emphasized that QLC-NAND is here to stay. Slow write speeds have been an Achilles' heel so far, but there should be progress in this area as well. The high surface density ensures one thing above all: lower manufacturing costs, because the more bits installed on the wafer, the better.
GDDR7 VRAM:37 Gbps
GDDR (Graphics Double Data Rate Memory, originally known as DDR SGRAM – Double Data Rate Synchronous Graphics RAM) was another highlight of Samsung's showcase. The latest advancement in this technology is GDDR7, which Samsung first unveiled at Tech Day 2022.
In July 2023, Samsung said it had completed the development of the industry's first Graphics Double Data Rate 7 (GDDR7) DRAM. The remainder of the year will be first installed in key customers' next-generation systems for validation, driving future growth in the graphics market and further solidifying Samsung's technology leadership in this field.
Samsung said its 16 Gb GDDR7 product will deliver the industry's highest speeds to date, following the company's development of the industry's first 24Gbps GDDR6 DRAM in 2022. Innovations in integrated circuit (IC) design and packaging provide greater stability despite high speeds.
"Our GDDR7 DRAM will help improve the user experience in areas that require excellent graphics performance, such as workstations, PCs, and gaming consoles, and is expected to expand into future applications such as artificial intelligence, high-performance computing (HPC), and automotive. Yongcheol Bae, executive vice president of Samsung Electronics' memory product planning team, said. "The next generation of graphics DRAM will be brought to market based on industry demand, and we plan to continue to lead the way in this field. ”
Samsung further noted that GDDR7 achieves an impressive 1.5 TBps bandwidth, which is 1.4 times faster than GDDR6 1.1 TBps, and boosts the speed to up to 32 Gbps per pin. These enhancements are achieved through the Pulse Amplitude Modulation (PAM3) signaling method adopted by the new memory standard instead of the non-return-to-zero (NRZ) signaling method of previous generations. PAM3 allows 50% more data to be transmitted than NRZ in the same signaling cycle.
It's worth noting that, as Samsung says, the latest design delivers a 20% improvement in energy efficiency compared to GDDR6 through power-saving design techniques optimized for high-speed operation. For applications where power consumption is particularly important, such as laptops, Samsung offers a low operating voltage option.
In order to minimize heat generation, in addition to IC architecture optimization, Samsung has adopted epoxy molding compounds (EMCs) with high thermal conductivity in the packaging materials of the next-generation GDDR. To this end, these improvements result in a significant 70% reduction in GDDR 7 thermal resistance compared to GDDR6, contributing to stable product performance even at high speeds.
But Samsung doesn't stop there, and at the upcoming five-day IEEE International Solid-State Circuits Conference 2024 in San Francisco in February, Samsung will present its new GDDR7 presentation, where they will present a paper titled "A 16Gb 37 Gb/s GDDR7 DRAM with PAM3-Optimized TRX Equalization and ZQ Calibration". Although there are not many details, as you can see from the title, Samsung has increased the speed of GDDR 7 to 37 Gb/s.
GDDR7 memory will utilize PAM3 and NRZ signals and is designed to achieve data rates of up to 37 Gbps per pin. Its development involves increasing the signal transmission rate and burst size without significantly raising the internal clock of the memory cell. This allows each GDDR version to increase the memory bus frequency, which improves performance.
However, as the frequency increases becomes more complex, the industry is exploring other solutions. For example, GDDR6X replaces traditional NRZ encoding with PAM4 encoding, effectively doubling the data transfer rate. PAM4 also significantly reduces signal loss due to the reduced baud rate.
However, GDDR7 will utilize PAM3 encoding, which is a compromise between PAM4 and NRZ signals. This results in a higher data transfer rate per cycle than NRZ, reducing the need for higher memory bus frequencies. GDDR7 promises better performance than GDDR6, as well as lower power consumption and implementation costs than GDDR6X.
With PAM3 signals instead of traditional signaling methods, GDDR7 VRAM is expected to deliver a huge improvement not only in bandwidth, but also in power consumption (at the same level as GDDR6/X performance). Of course, getting the most out of GDDR7 can still see that it uses comparable power to modern GDDR6 configurations, only with more performance per watt. The next version of USB4 is also expected to feature PAM3 signals to reduce power consumption.
In addition, GDDR7 provides a way to optimize memory efficiency and power consumption. This includes four different read clock modes so that it only runs when needed. The GDDR7 memory subsystem can also issue two separate commands in parallel, optimizing power consumption.
As for its release, GDDR7 is expected to be released alongside next-generation GPUs from AMD and NVIDIA, most likely later this year.
It is worth mentioning that two versions of GDDR7 VRAM are expected to appear at the ISSCC this year: the low-power 35.4 Gb/s per pin GDDR7 from SK hynix, and the higher power 37 Gb/s per pin GDDR7 from Samsung. And according to Micron, GDDR6X has a bandwidth of about 19-24 Gigabits per pin.
3D DRAM, ahead of schedule
In addition to NAND and GDDR, Samsung also announced the company's 3D DRAM layout.
3D DRAM is a memory chip with a new structure that breaks the current paradigm of aging. Existing DRAM product development focuses on increasing integration by reducing the line width, but as the line width moves into the 10 nm range, physical limitations such as capacitor current leakage and interference increase significantly. In order to prevent this from happening, new materials and equipment such as high dielectric constant (high K) deposition materials and extreme ultraviolet (EUV) equipment have been introduced. But the semiconductor industry believes that miniaturization of 10nm or more chips will pose a huge challenge for chipmakers.
According to reports, Samsung Electronics has confirmed that it has formed a new next-generation memory research and development (R&D) organization to seize the 3D DRAM market, which is often referred to as "dream memory". According to industry sources, Samsung Electronics' semiconductor (DS) division recently set up a cutting-edge memory R&D facility at Silicon Valley's semiconductor U.S. headquarters (DSA). Led by Song Jae-hyeok, Chief Technology Officer (CTO) of Samsung Electronics' DS Division and Director of the Semiconductor Research Institute, the organization is committed to pioneering research on 3D DRAM.
3D DRAM has been hailed as a "game-changer" in the memory semiconductor industry and has the potential to revolutionize the global DRAM market landscape. While current DRAM has a 2D structure where cells are densely packed in a single plane, 3D DRAM can significantly improve performance by increasing the density of the same area, whether by placing cells horizontally and stacking them upwards, or by using a two-layer vertical approach.
Samsung Electronics is also betting on 3D in the DRAM field based on its experience in commercializing 3D vertical NAND in 2013, which was the first in the world to commercialize 3D vertical structures.
At IEEE EDTM 2023 at COEX in Seoul on March 10 last year, Lee Jong-myung, vice president and head of the process development office at Samsung Electronics' Semiconductor Research Center, said, "3D DRAM is considered to be the future growth driver of the semiconductor industry. Cha Seon-yong, vice president of SK hynix, who is in charge of SK hynix's Future Technology Research Institute, also said on March 8, 2023, "By next year (2024), details about the electrical characteristics of 3D DRAM will be announced to determine their development direction." ”
Last October, at Samsung's Memory Technology Day 2023 in Silicon Valley, Lee Jeong-bae, president of the memory business, announced, "We will be the first to introduce new 3D vertical structures in sub-10nm DRAM." They claim that the new structure of sub-10nm DRAM will allow for more than 100 GB of capacity on a single chip.
Industry experts believe that the first companies to develop and mass-produce 3D DRAM will take a leading position in the next-generation DRAM market, echoing the layer competition in the NAND flash memory market.
Technology competition in the 3D DRAM space is also intensifying. According to semiconductor technology analyst firm TechInsights, Micron, which ranks third in the memory semiconductor market, is actively preparing for the blue ocean market and has obtained more than 30 3D DRAM patents by August 2022. In comparison, Samsung has only 15 patents related to 3D DRAM, and SK hynix has only about 10.
In addition to the above technologies, HBM is also a focus for Samsung, which is also an area that Micron and SK hynix are investing heavily in.
[Source: Semiconductor Industry Observation]