Samsung said this week that it is developing 24Gb DDR5 memory devices at the request of customers operating cloud data centers. Such ICs will enable the company to build memory modules with capacities up to 768GB for servers and high-capacity memory solutions for client PCs. In addition, Samsung also disclosed some features of its DRAM technology using extreme ultraviolet (EUV) lithography.
24Gb DDR5 chip under development
“In order to meet the needs and requirements of cloud companies, we are also developing the largest 24Gb DDR5 products,” Samsung executives said at the earnings conference this week, according to Find Alpha.
Samsung has shown its 512GB registered DIMM (RDIMM) memory module, using 32 16GB stacks based on 8 16Gb DRAM devices. The 8-Hi stack uses TSV interconnects to ensure low-power and high-quality signal transmission.
By using 24Gb memory ICs in the 8-Hi stack, Samsung can increase the capacity of a stack to 24GB and the capacity of a 32-chip module to 768GB. Using such RDIMMs, a server CPU with 8 memory channels and two modules per channel can be equipped with more than 12TB of DDR5 memory. To put this number in context, today’s Intel Xeon Scalable “Ice Lake-SP” CPUs are designed for workloads that require large amounts of memory and can support up to 6TB of DRAM.
In addition, Samsung can build 96GB, 192GB, or 384GB modules for mainstream and ultra-dense servers with no more than one RDIMM per channel, but it can certainly take advantage of additional DRAM capacity.
For client applications, using 24Gb memory chips instead of 16Gb ICs can increase memory module capacity by 50%, so it is expected that 24GB and 48GB DDR5 modules will be used at some point. At the same time, Samsung pointed out that 16Gb DDR5 devices will become the mainstream at present, so even if 24Gb devices will be used for client applications, don’t expect too fast.
DRAM shrinking becomes more difficult
In addition to increasing data transfer rates and performance enhancements, one of the key features of DDR5 memory is the ability to increase the capacity of each device up to 64Gb (16Gb in the case of DDR4) and stack up to 8-16 DRAMs (depending on (In terms of capacity) in one chip (four in the case of DDR4).
It is challenging to triple the capacity of memory IC devices from 16Gb to 32Gb, because as newer process technologies no longer provide tangible node-to-node density improvements, it becomes increasingly difficult to shrink DRAM transistor and capacitor structures. For example, Samsung calls its most advanced DUV-only manufacturing process the 15nm node, while its latest D1a technology relies on EUV spanning five layers, called 14nm.
“Our 14-nanometer DRAM is the smallest design rule in the industry’s 14-nanometer class,” said a Samsung executive. “We will mass-produce this product by applying EUV to five layers in the second half of the year.”
From 15 nanometers to 14 nanometers, such a small step is determined by Samsung’s conservative approach and is unwilling to increase the risks associated with using new equipment and actively increasing density. However, it still emphasizes that even with the use of DDR5 and its enhancements to increase yield and EUV lithography, increasing the density per device will not be so easy. For this reason, it is completely reasonable for Samsung to develop 24Gb DDR5 equipment.
Previously, the company did not disclose the number of EUV layers used by D1a. By using EUV instead of DUV’s multiple modes, Samsung has reduced the number of process steps and DRAM costs. Samsung is currently providing customers with samples of 16Gb DRAM based on 14 nm D1a, and plans to start mass production in the second half of 2021.
Samsung is the first memory manufacturer to pre-announce its 24Gb DDR5 IC, and will be one of the first manufacturers to utilize such high-capacity DRAM devices. The only question is when.
Perhaps due to competition reasons, Samsung did not disclose when it plans to start producing 24Gb DDR5 DRAM and high-capacity memory modules on its basis. When Intel’s Xeon Scalable “Sapphire Rapids” processor is launched in mid-2022, in order to meet the urgent demand for ultra-high-capacity DDR5 memory modules, Samsung has 16Gb-based 512GB RDIMMs and is currently providing samples to various server customers .
Therefore, high-capacity modules based on 24Gb may sometimes be launched later, unless customers are willing to deploy them as soon as possible without a long verification process.