SK hynix starts mass production of speedy, 238-Layer NAND

SK hynix said late on Wednesday that it had begun mass production of its 238-layer “4D” (actually a form of 3D) NAND memory devices that promise to enable high-performance and high-capacity SSDs. The new chips boast a 2400 MT/s data transfer rate and could be used to power the next generation of best SSDs, high-speed models what will featuring a PCIe 5.0 x4 interfaces and offer sequential read/write speed of 12 GB/s and higher. 

From a performance PC enthusiast’s point of view, the key advantage of SK hynix’s 238-layer TLC NAND IC is its interface speed of 2400 MT/s. This represents a 50% increase over prior generation and is something that is needed to build SSDs with sequential read/write speeds of 12 GB/s and higher as 3D NAND devices with a 1600 MT/s interface cannot enable transfer rates to saturate a PCIe Gen5 x4 interface. 

SK hynix’s first 238-layer 3D NAND device is a 512Gb (64GB) 3D TLC device that has a 34% higher manufacturing efficiency than a comparable device fabricated on the company’s 176-layer 3D NAND node, the company said. Assuming that yields of the 238L TLC NAND IC are high, it will significantly — by up to 34% — decrease bit costs and therefore increase the device’s cost competitiveness. In addition to being smaller than predecessors, the new devices are said to reduce power consumption during reads by 21%, which is a benefit for mobile PCs as well as smartphones.

Typical for SK hynix, the 238-layer NAND device sports a charge trap flash (CTF) design, and it employs the company’s proprietary peripheral under cells (PUC) layout, a feature the manufacturer labels as ‘4D’ NAND. This particular layout allows for a reduction in the size of the memory devices, thus facilitating further cost reduction for SK Hynix’s NAND. 

SK hynix plans to use the new 238-layer memory for smartphones first and then expand its usage across portfolio of other products.

“SK hynix has developed solution products for smartphones and client SSDs which are used as PC storage devices, adopting the 238-layer NAND technology, and has moved into mass production in May,” a statement by the company reads. “Given that the company secured world-class competitiveness in price, performance and quality for both 238-layer NAND and the previous generation 176-layer NAND, we expect these products to drive earnings improvement in the second half of the year.”