SK Hynix recently released details about its 8th generation 3D NAND memory device with over 300 active layers. The company’s new he 3D NAND devices could improve SSD performance and reduce cost per TB when they arrive sometime between 2024 and 2025.
SK Hynix’s first 8th generation 3D NAND device with 300+ layers features 1Tb (128GB) capacity with triple level cells and over 20Gb/mm^2 bit density. Additionally, the chip features a 16KB page size, four planes, a 2400 MT/s interface, and a maximum throughput of 194 MB/s (18% higher than the 7th generation 238-layer 3D NAND). Faster I/O and increased throughput are especially useful for the best SSDs with PCIe 5.0 x4 or higher interfaces.
Nearly doubling the bit density of the new NAND would significantly improve productivity per wafer for the new manufacturing node and reduce SK Hynix’s cost, but by how much is unknown.
To improve the design, SK Hynix had to implement five new schemes.
- The Triple Verify Program (TPGM) feature narrows the cell threshold voltage distribution, reduces tPROG (program time) by 10%, and improves performance.
- Adaptive Unselected String Pre-Charge (AUSP) — Another procedure that reduces tPROG by approximately 2%.
- All Pass Rising (APR) scheme reduces tR (read time) by approximately 2% and reduces word line rise time.
- The programmed dummy string (PDS) technique reduces the world line settling time of tPROG and tR by reducing channel capacity loading.
- The Plane-Level Read Retry (PLRR) feature allows plane read levels to be changed without terminating other users, allowing subsequent read commands to be issued immediately, improving quality of service (QoS) and increasing read performance. can be improved.
SK Hynix has not disclosed when the 8th generation 3D NAND device will go into production. However, it seems that the development is complete or nearing completion, as the company has released details of the technology. On the other hand, all flash memory makers tend to delay adoption of new manufacturing nodes to limit NAND bit output, so it is unlikely that SK Hynix will rush production of 8th Gen 3D NAND. Therefore, it is reasonable to expect the new memory he will be adopted in 2024.
