Kioxia and Western Digital have jointly introduced their latest storage device, the 8th Generation BiCS 3D NAND memory with 218 active layers. The new device boasts a 1Tb capacity in 3D TLC mode, coupled with a 3200 MT/s data transfer speed, making it ideal for high-performance, high-capacity drives for SSD makers. The architecture of the new device is similar to YMTC’s Xtacking, which enables such an extreme interface speed.
BiCS 3D NAND memory is a type of flash memory technology that uses a three-dimensional (3D) stacked cell structure. This technology was jointly developed by Toshiba Memory (now Kioxia) and Western Digital. The name “BiCS” stands for “Bit Cost Scaling,” which refers to the ability of this technology to scale up the density of memory cells while maintaining low manufacturing costs. BiCS 3D NAND memory allows for higher capacity and faster read/write speeds compared to traditional 2D NAND memory, making it suitable for a wide range of data storage applications such as solid-state drives (SSDs), smartphones, and data centers.
Triple-level cell (TLC) and quad-level cell (QLC) are two types of flash memory technologies used in solid-state drives (SSDs). TLC flash memory can store three bits of data per memory cell, while QLC flash memory can store four bits of data per memory cell. This makes QLC denser than TLC, but it also makes it slower and less durable. Both TLC and QLC are used to maximize storage density and expand addressable applications, meaning that they allow for higher capacity SSDs to be built.
The 218-layer BiCS 3D NAND device supports triple-level cell (TLC) and quad-level cell (QLC) configurations, maximizing storage density and expanding addressable applications. Kioxia and Western Digital incorporated their new ‘lateral shrink technology’ to increase bit density by over 50%, indicating that developers also shrank lateral sizes of NAND cells to fit in more of them per layer.
The 218-layer 3D NAND device features a quad-plane architecture that allows for a higher level of parallelism for programming and read times, providing increased performance. Additionally, the 218-layer 3D TLC device has a 3200 MT/s input/output interface, the highest I/O speed announced so far. High data transfer rates will be handy for high-end client and enterprise SSDs featuring a PCIe 5.0 interface.
The key innovation of the 8th Generation BiCS 3D NAND memory is the all-new CBA (CMOS directly Bonded to Array) architecture. This new technology involves producing memory cells and peripheral circuits separately, allowing manufacturers to make them using the most efficient process technologies in their sections of cleanrooms, bringing further benefits as the industry adopts methods like string stacking.
CBA stands for “CMOS directly Bonded to Array.” It is a new architecture used in the 8th Generation BiCS 3D NAND memory jointly developed by Kioxia and Western Digital. The CBA architecture involves separately producing 3D NAND cell array wafers and I/O CMOS wafers using the most optimal process technologies and then bonding them together to create a final product that offers increased bit density and fast NAND I/O speed. The separate production of memory cells and peripheral circuits solves several problems, as it allows manufacturers to make them using the most efficient process technologies in their sections of cleanrooms, which can bring further benefits as the industry adopts methods like string stacking.
Kioxia has started sample shipments of the 8th Generation BiCS 3D NAND memory devices to select customers. Still, there is no word on when the company expects to initiate volume production of its next-generation flash memory. However, industry experts expect the 8th Gen BICS to hit the market in 2024.
“Through our unique engineering partnership, we have successfully launched the eighth-generation BiCS Flash with the industry’s highest bit density,” said Masaki Momodomi, Chief Technology Officer at Kioxia Corporation. “By applying CBA technology and scaling innovations, we’ve advanced our portfolio of 3D flash memory technologies for use in various data-centric applications, including smartphones, IoT devices, and data centers.”
