375 Layers! SK Hynix to Mass-Produce Next-Gen NAND by Year-End

According to South Korean media, SK Hynix will begin mass production of its next-generation 375-layer 3D NAND flash memory by the end of this year. The company has completed production validation for the 375-layer NAND and is now preparing to transition the manufacturing line to the mass-production phase.

Rather than building a new factory, SK Hynix is upgrading the existing production lines at its Cheongju M15 plant—which currently produces 176-, 238-, and 321-layer products—and investing in converting them into 375-layer production lines.

Adjustment from 400 to 375 Layers; Future Roadmap Targets 604 Layers

It is reported that this NAND was initially planned as a 400-tier product. However, due to the high manufacturing difficulties associated with ultra-high-layer stacking (such as channel hole etching), the layer count was ultimately adjusted to 375. According to SK Hynix's technology roadmap, the company will continue to iterate by successively launching 480-layer and eventually 604-layer products.

Core Technological Highlight: Replacing Tungsten with Molybdenum

The most significant change in this technological iteration is the introduction of molybdenum (Mo) to replace some traditional tungsten (W) thin films. In 3D NAND flash memory, the metal gate electrodes controlling each memory cell (known as word lines) are typically made of tungsten. As the number of stacked layers increases, the wiring becomes increasingly minute, exposing the shortcomings of traditional tungsten: when the lines are scaled down, electrical resistance rises significantly, slowing signal transmission rates. Additionally, tungsten requires an extra barrier layer before filling; stacking these layers causes thickness loss and occupies valuable space.

In contrast, under the same miniaturized dimensions, molybdenum exhibits lower electrical resistance, effectively accelerating data read/write speeds. More importantly, molybdenum can be directly filled without the need for an additional barrier layer, which helps further increase the storage density of the chips. However, since molybdenum precursors are solid at room temperature, production requires specialized equipment for high-temperature heating, along with precise control over the supply volume and delivery rate of the materials, posing extremely stringent demands on both equipment and process management.

Equipment Selection and Supply Chain Layout

Samsung Electronics had already adopted molybdenum in its metal wiring process for its 9th-generation 286-layer 3D NAND flash memory, which began mass production in April 2024. Its next-generation 10th-generation 3D NAND flash will exceed 400 layers and is currently being prepared for commercialization in the second half of this year, with an expanded application scope for molybdenum.

Regarding equipment selection for the molybdenum deposition process, Samsung Electronics opted for Lam Research's single-wafer processing equipment. After evaluation, SK Hynix ultimately chose TEL's furnace-type processing equipment. While AMAT's equipment uses a single-wafer processing mode capable of handling only one wafer at a time, TEL's equipment can deposit materials on up to a hundred wafers simultaneously, offering greater cost advantages in terms of equipment pricing, installation footprint, and molybdenum consumption.

On the supply chain front, Air Liquide, Entegris, and Merck will supply molybdenum materials to SK Hynix. Among domestic South Korean companies, SK Specialty is also considered a potential supplier. However, as it lacks its own warehousing and supply facilities, both parties are discussing a plan for SK Specialty to borrow Air Liquide's supply system for delivery, with SK Hynix actively promoting cooperation between the two companies.

Surging Industry Demand; Profitability-Oriented Strategy Becomes Core Driver

With the evolution of 3D NAND processes, industry demand for molybdenum is expected to grow rapidly. Industry estimates show that Samsung Electronics' molybdenum procurement was about 4 tons last year and is projected to increase to 10 tons this year, potentially reaching 80 tons by 2030. SK Hynix will also begin large-scale adoption of the molybdenum process starting next year, with initial annual procurement estimated at around 4 tons.

Industry insiders point out that the current NAND market has bid farewell to the era of blind capacity expansion and has fully shifted toward a "profitability-oriented" approach. SK Hynix has adopted a similar strategy in its NAND business: instead of adding new capacity, it is reducing the output of lower-layer NAND products while expanding the production scale of 375-layer products, thereby improving per-bit output efficiency and lowering production costs.