SK Hynix Pivots NAND Competition to Material Innovation with 375-Layer Chip

SK Hynix Elevates NAND Competition: A Paradigm Shift Towards Material Advancement

In a significant strategic maneuver, SK Hynix is redefining the competitive landscape for next-generation NAND flash memory. The company is transitioning its focus from simply achieving higher layer counts to pioneering material innovations, signaling a crucial evolution in the industry. This forward-thinking approach aims to address inherent limitations and unlock new performance benchmarks in semiconductor storage.

Beyond Stacking: The Era of Material Innovation

According to a recent report by Korean semiconductor media outlet TheElec, SK Hynix is set to begin mass production of its 375-layer 3D NAND flash memory by the end of this year. The company has successfully completed production validation for this advanced product and is preparing for its transfer to mass production lines. This significant undertaking will not require the construction of new facilities but will be achieved by retrofitting existing NAND production lines at the M15 factory in Cheongju, South Korea. These lines currently produce 176-layer, 238-layer, and 321-layer NAND products.

While internally referred to as "400-class" NAND, the final layer count has been adjusted to 375. This adjustment is driven by the escalating manufacturing complexities associated with higher layer counts. Processes such as channel hole etching become considerably more challenging, imposing limitations on stacking height, yield rates, and overall process stability. Industry insiders suggest that SK Hynix's future roadmap includes the development of 480-layer and 604-layer products, underscoring their commitment to pushing the boundaries of NAND technology.

Molybdenum: The Key Material for Enhanced Performance

Perhaps the most noteworthy aspect of the 375-layer NAND is SK Hynix's plan to introduce molybdenum (Mo). This advanced material is slated to partially replace tungsten (W), traditionally used for metal gate electrodes, specifically in the word lines. NAND technology achieves higher densities by vertically stacking numerous memory cells and the word lines that control them. As the number of layers increases, the word line structures become thinner, exacerbating the resistance issues associated with conventional tungsten materials.

Molybdenum is emerging as a prime candidate to resolve this challenge. Experts from Lam Research have indicated that atomic layer deposition solutions for molybdenum can deliver over 50% improvement in resistance compared to traditional tungsten metallization in many scenarios. Semiconductor Engineering has also highlighted that as word lines thin, increased tungsten resistance degrades performance, making low-resistance materials like molybdenum and ruthenium (Ru) key areas of research.

For NAND flash, lower resistance translates directly into faster signal transmission, promising improvements in program write and read latency. Furthermore, it contributes to reduced power consumption. While this may not immediately result in a generational leap in single-chip performance, it signifies that the bottlenecks in high-layer NAND are no longer solely about the feasibility of stacking, but also about maintaining speed, power efficiency, and reliability once stacked.

Samsung's Preemptive Material Integration

It is important to note that SK Hynix is not the sole industry player exploring molybdenum. Reports indicate that Samsung Electronics began incorporating molybdenum into its metal wiring process with the ninth-generation 286-layer 3D NAND, which entered mass production in April 2024. Samsung is also preparing for the commercialization of its tenth-generation 3D NAND, exceeding 400 layers, in the latter half of this year, further expanding its use of molybdenum in its manufacturing processes.

This development positions the 375-layer NAND not just as an upgrade for SK Hynix but also as a competitive response in the ongoing race for high-layer NAND advancements being pursued by manufacturers such as Samsung, Kioxia, and Micron. SK Hynix has demonstrated rapid progress in high-layer stacking over the past two years, announcing the world's first mass production of 321-layer NAND in 2024, with customer shipments planned for the first half of 2025. Following this, SK Hynix aims to initiate mass production of 321-layer 2Tb QLC NAND in 2025, targeting higher density storage applications, with expected customer release in the first half of 2026 after validation. This QLC variant will increase the number of independently operating units within the chip from four to six, mitigating potential performance degradation associated with large-capacity QLC NAND.

AI Storage Demands Reshape NAND Expectations

This wave of NAND upgrades is occurring against the backdrop of rapidly expanding artificial intelligence (AI) storage requirements. SK Hynix introduced its "AI-NAND" product line at last year's OCP Global Summit, catering to diverse needs in performance, bandwidth, and density. The company has emphasized that the growth in the AI inference market is significantly increasing the demand for NAND storage capable of fast and efficient processing of massive datasets.

Recent reports from Reuters also detail a multi-year collaboration between Nvidia and SK Group, wherein SK Hynix will develop advanced storage solutions for global AI data centers and expand its wafer production capacity. Nvidia CEO Jensen Huang has stated that current capacity expansions are still insufficient to meet future AI demands.

The successful mass production of the 375-layer NAND by year-end hinges on the efficient retrofitting of the M15 production line, the ramp-up of yield rates, and the progress of customer validation. The true measure of success will not solely be the number of layers SK Hynix can stack, but the stability and scalability of molybdenum integration in high-layer products, ushering in a new era of semiconductor storage innovation.