「Tungsten Out, Molybdenum In」: Behind SK Hynix's 375-Layer NAND, the Real Winners Are These Two Types of Upstream US Stocks

Original Author: Ada, TechFlow on Deep Tide

According to industry research firm TrendForce, SK Hynix has completed the design verification of 375-layer NAND, with mass production scheduled to begin by the end of 2026. The company will convert existing production capacity for manufacturing. The completion of SK Hynix's 375-layer NAND verification has brought a long-brewing industry inflection point to the forefront: tungsten, which has been used in chips for nearly a quarter of a century, is being replaced by molybdenum. The real winners of this material substitution are not the memory manufacturers, but the upstream suppliers of equipment and consumables.

Tungsten Lasted Nearly 25 Years, Scaling is Pushing its Physical Limits

It is worth noting that Samsung, not SK Hynix, was the first to introduce molybdenum in metal wiring. Samsung had already adopted molybdenum in its 9th-generation 286-layer NAND, which began mass production in April 2024, and is currently expanding the use of molybdenum to more process steps. SK Hynix's current effort marks the first use of molybdenum on its product line, positioning it as a follower within the industry landscape, rather than a pioneer.

This 375-layer product itself has a history of downward revision. According to TheElec, SK Hynix initially targeted the 400-layer level internally, but due to the manufacturing complexity of high-layer stacking, it ultimately scaled back to 375 layers. Even so, it represents a crucial leap on SK Hynix's NAND roadmap, and future 480-layer and 604-layer products are expected to rely more heavily on molybdenum.

Although the replacement of tungsten with molybdenum is not exclusive to the memory sector, it has created an industry-wide inflection point. Reports indicate that tungsten has been used as an interconnect metal in NAND, DRAM, and the middle-of-line (MOL) processes of logic/foundries for nearly 25 years. However, scaling requirements are now pushing against tungsten's boundaries, making molybdenum the most promising alternative candidate.

The advantages of molybdenum extend beyond lower resistance. Unlike tungsten and copper, molybdenum does not require a barrier layer to prevent diffusion, simplifying the process and improving yield. Its high melting point and oxidation resistance support direct deposition, making it more suitable for high-aspect-ratio structures like 3D NAND and logic GAA (Gate-All-Around). In other words, the more layers stacked and the smaller the nodes become, the more challenging tungsten becomes, and the greater the penetration potential for molybdenum. This is the very foundation of the "pick-and-shovel seller" logic; once the substitution begins, the beneficiaries are the providers of tools and materials.

Lam Research: The Only Pick-and-Shovel Seller with Mass-Produced ALD Molybdenum Tools

The most direct and compelling narrative in this chain is Lam Research (LRCX). The company's ALTUS Halo, launched in February 2025, is described as the industry's first atomic layer deposition (ALD) tool designed for molybdenum in mass production. In most cases, it achieves over 50% improvement in resistance compared to traditional tungsten metallization. Lam disclosed that early adoption has already begun in high-capacity 3D NAND fabs in South Korea and Singapore, as well as advanced logic fabs. South Korea corresponds to Samsung and SK Hynix, while Singapore corresponds to Micron.

The business leverage lies in the increasing complexity of processes. According to Zacks Research, Lam is currently the only supplier with ALD molybdenum tools already in mass production, serving foundry and NAND customers. While molybdenum deposition is slower and more complex, it allows Lam to triple its serviceable addressable market (SAM) for single-wafer metal deposition at these advanced nodes. The harder the process becomes, the greater the incremental benefit for equipment suppliers.

Entegris Sells Consumables, Micron is the Only Pure-Play Memory Stock on US Markets

Applied Materials (AMAT) takes a different path. In February, it launched the Spectral ALD system, which replaces tungsten with molybdenum in today's transistor contacts, reducing resistance at the critical connection point between the transistor and the copper wiring network. This system has already been adopted by multiple leading logic foundries. A distinction is necessary: Lam's molybdenum story leans towards NAND/DRAM word lines, while AMAT's molybdenum story leans towards 2nm GAA logic contacts. Their downstream applications differ and cannot be grouped under the same beneficiary logic.

A representative in the materials sector is Entegris (ENTG). The company supplies molybdenum solid precursors, specifically molybdenum dichloride dioxide (MoO₂Cl₂), tailored for DRAM and 3D NAND, and pairs it with the ProE-Vap delivery system. Its logic lies in the ripple effects of material switching. According to Entegris, the shift from copper and tungsten to molybdenum will impact multiple areas, including precursor selection, polishing pad design, slurry formulation, etching materials, and filtration. The process becomes more fragmented but spans multiple steps.

As for the memory manufacturers themselves, Samsung and SK Hynix are not listed on the main US stock exchanges. Micron (MU) is the only pure-play memory stock in the US market and has gained a head start with molybdenum. Lam cited Mark Kiehlbauch, VP of NAND Development at Micron, who stated that molybdenum metallization allowed Micron to achieve industry-leading I/O bandwidth and storage capacity in its latest generation of NAND products. However, Micron is a "user of molybdenum" rather than a "beneficiary from selling molybdenum." Its stock price is primarily driven by memory cycles and HBM; molybdenum is merely a performance enhancer.

Molybdenum Miners Cashing In? Semiconductor Demand is Just a Drop in the Bucket

Theoretically, molybdenum miners can also be considered peripheral beneficiaries of this narrative. A relevant US stock counterpart is Freeport-McMoRan (FCX), which produces molybdenum as a copper by-product. However, the volume of molybdenum used in semiconductors is extremely small. According to TheElec and industry estimates, Samsung purchased approximately 4 tons of molybdenum last year and around 10 tons this year, while SK Hynix starts with about 4 tons. Even by 2030, the total industry consumption is expected to be merely around 80 tons. Compared to the global molybdenum market, dominated by steel alloys and consuming hundreds of thousands of tons annually, semiconductor demand is negligible. Linking miners' stock prices to the NAND narrative is an untenable causal relationship.

This delineates the true focal point of the "tungsten out, molybdenum in" story. SK Hynix's 375-layer NAND is just the starting point; the real scope spans three major categories: NAND, DRAM, and materials. In this metal generational shift, the probability of certainty is higher for those selling tools and consumables. Memory manufacturers using molybdenum are beneficiaries in terms of performance, not valuation, while the metal mining side essentially reaps little benefit.

Disclaimer: This article does not constitute any investment advice.