Flash Memory Summit 2022 Announcements

Although the FMS is expanding to include all solid-state storage, not just flash memory, there were several product and technology announcements at Flash Memory Summit 2022. Let’s look at announcements from Kioxia, Western Digital, YMTC, FADU, Solidigm (SK hynix), Samsung, NVIDIA and Neo Semiconductor.

During Kioxia’s keynote, the company discussed its software-defined flash API (software-enabled flash) for more efficient flash implementation in data centers. They have stated that their Ethernet-connected SSDs can be used for storage disaggregation and are certified for GPUDirect storage. The company also offers the E1.S (XD6) and E3.S (CM7) SSD form factors. The CM7 made its debut at the FMS.

Kioxia, along with the company’s factory partner, Western Digital, discussed NAND scaling. As shown in the slide below, the density of 3D NAND flash memory depends on more factors than the number of layers. In particular, it is also lateral scaling, logical scaling, and architectural scaling (especially chip or chip stacking).

Western Digital also talked about moving NAND flash memory into adjacent market niches, such as providing storage-class memory that complements DRAM. They also talked about the different ways to scale NAND flash and showed a roadmap of up to 500+ layers by 2032 but also implementing other density improvements as shown below. As for logical scaling with more bits per cell, WDC talked about 4.5 bits per cell products before moving to 5 bits per cell for cold storage applications.

Other design innovations that WDC talked about include asynchronous independent plan playback (aIPR) for improved random playback performance. A slide shows that the total annual production of NAND flash capacity in 2021 was 765 EBs with more than 2 ZBs planned for 2025.

YMTC out of China showed a photo of its manufacturing plant in China during its opening speech. YMTC is a pioneer in bonding wafers from a logic wafer to 3D NAND flash wafers as a way to achieve high density NAND flash. Slice bonding is done through millions of metal vias and YMTC calls this Xtacking. YMTC says this allows for smaller array sizes and higher bit densities. The company claims to have validated this wafer bonding technique and that it will work in mass production. To be successful, the YMTC had to overcome several challenges, as illustrated below.

YMTC said their 3rd generation Xtacking provides a 1 TB fabric with 6 planes that allows per-plane asynchronous multi-plane independent operations. The company said Xtacking opens up possibilities for many applications, as shown below.

FADU pointed out that power and heat will be the biggest challenges for SSDs used in data center applications and they indicate that this is a major focus of their product development.

Power is also an issue for many in-vehicle devices. During Samsung’s keynote, they showed 45% power efficiency (MB/s per mA) with their UFS 4.0 product compared to the previous generation UFS 3.1, using their own controller and 7e VNAND generation. The product will be available in Q# 2022. Samsung was also showing its 2n/a Generation SmartSSD with PCIe support for close data processing. The product includes an AMD versatile adaptive SoC and an ARM IP accelerator plus HW. The product achieves a 6X data throughput improvement by running PostgreSQL scan compared to a standard PCIe 4.0 SSD.

Solidigm, now part of SK hynix, was Intel’s NAND and SSD business. At FMS 2022, the company announced its first Solidigm-branded product, the P41 Plus SSD. This SSD is a PCIe 4.0 NVMe product for the client PC market. The drive features 144-layer 3D NAND and offers a sequential read speed of up to 4.1 GB/s. Capacities range from 512 GB to 2 TB.

Solidigm offers software running on the host machine called Solidigm Synergy which includes a storage driver and a Windows application with health monitoring tools. The P41 Plus includes SLC as well as flash and Synergy TLC software to provide host-managed caching by monitoring usage patterns to keep the most frequently accessed data in cache.

A demonstration showed that the P41 Plus worked twice as fast (when reading data) with the Synergy software than without the software. In a briefing, Solidigm said the P41 Plus can turn part of SLC flash into TLC flash and vice versa if needed. Synergy software leverages caching developments originally created for Intel’s Optane memory. The figure below is from SK hynix’s keynote.

Solidigm also benchmarked its D7-P5520 against an unnamed competitor enterprise SSD showing significant performance improvements. Solidigm’s 4D NAND core technologies are a side source to reduce alignment dependence, under-cell peripheral logic, and an advanced charge-tracing cell that has a wider cell voltage distribution window ( ~6 V was shown on a slide). During the keynote, they also announced a 512 GB 238-layer TLC chip (6 layers more than Micron’s recently announced 232-layer 3D NAND. Mass production of this chip is to begin in the first half of the year. 2023, see below There has been a 10% performance gain with each 4D NAND generation.

Solidigm/SK hynix also announced a 175-layer 1TB QLC NAND that will begin mass production in Q4 22 and said that a QLC for mobile products with the 238-layer technology is under development. The company also said it was working on a NAND PLC (5 bits per cell) device for near-field applications. This technology is for a 1.67TB 192-layer chip.

During an FMS session on Thursday, SK hynix demonstrated a next-generation smart storage product and Key Value Store (KV-CSD) computing storage device with enhanced write and read capabilities for high-performance computing.

Samsung was also showing off its first PCIe 5.0 SSD that they claim was in mass production, the PM1742, pictured below (it won an award at CES 2022). As noted, moving to PCIe Gen 4 from 3 has dramatically improved bandwidth and power efficiency.

Samsung also announced a 24G dual-port SAS SSD (the PM1653) that boasts 2X bandwidth and a 31% increase in power efficiency over previous 12G SAS SSDs. Samsung said its V8 TLC VNAND product will be launched with physical scaling and improved storage capacity with the same volume. Samsung also talked about die stacking technology for its SSDs for very high capacity implementations. The table below gives their 32-chip stacking capacity projections, with 1PB capacities possible in 10 years. Samsung was also showing off its wide range of SSD form factors for different applications and enclosures.

NVIDIA spoke at Samsung’s keynote on GPU direct storage, showing and AIC JBOF with a Samsung SSD and BlueField DPU, see below. They also discussed PBSSD, an NVMe subsystem for disaggregated storage with higher rack efficiency for PB-scale storage.

Neo Semiconductor in its keynote talked about its new NAND Flash and DRAM architectures. With their aggregate sense amplifier, upper plane architecture, their X-NAND delivers 3x random read/write speed and 20x sequential R/W speed. Their X-DRAM has 50% lower turn-on latency and requires only 15% refresh power consumption. The figure below shows the basic concept applied to DRAM.

By aggregating four bitlines to a sense amplifier, they can create 4 DRAM memory planes and shorter bitlines with shorter bitline delay and lower power consumption. This also results in a much higher data rate. This can be applied with even more sense amplifier aggregation to further increase performance.

The figure below shows the overall modeled benefits of this architecture change for DRAM.

A similar approach can be taken with NAND flash by aggregating page buffers. The figure below shows a first generation X-NAND TLC with all four page buffers instead of one and a second generation with eight page buffers. Note that the first generation is modeled to have data rates of 1.6 GB/s compared to 160 MB/s with conventional NAND. Neo speculates that X-NAND could provide a storage class memory layer between SSDs and DRAM using SLC or MLC NAND and an SSD storage layer using TLC and QLC NAND. They even discussed the possibility of replacing the hard disks with NAND PLC or HLC (six bits per cell).

FMS 2022 included several new flash memory announcements. Solidigm (SK hynix) has announced a 238-layer NAND flash as well as a PLC NAND flash chip. WDC/Kioxia spoke of over 500 diapers by 2032. YMTC spoke of their 3rd generation wafer bonding technology, Samsung was showing off its PCIe Gen 5 SSD and said that 32 chip stacks with 1PB capacity would be possible in 10 years. FADU talked about the need for power and temperature control in enterprise SSDs. NVIDIA discussed PBSSD for disaggregated petabyte-scale NVMe storage. Neo Semiconductor talked about a higher performance NAND and DRAM architecture.

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