Samsung weighs outsourcing DDR5 and a TSMC route for HBM4 base dies

Samsung Electronics is drawing up plans to hand commodity DDR5 production to outside partners, and weighing whether the base dies inside next-generation HBM4 should come from TSMC, according to industry sources. The quietly enormous point: the one-stop, everything-in-house model that defined the memory industry is cracking under AI demand, and TSMC may end up sitting inside both rival HBM4 camps.

TSMC Watch analysis

What happened

Industry sources told BigGo Finance, in a report published on 16 September, that Samsung is pursuing a two-track reshuffle. Commodity DDR5 module assembly and some SSD production would move to external packaging and testing providers, freeing Samsung's Cheonan and Onyang back-end lines to concentrate on high-bandwidth memory. Samsung has been asking partners to expand DDR5 and SSD capacity since June last year, and pressed for faster timelines earlier this year.

The second track is the one with strategic teeth. Starting with HBM4, the base die that manages data flow inside stacked memory behaves like a logic chip, so it is built on foundry processes rather than conventional DRAM ones. Samsung has so far made its HBM4 base dies on its own 4nm process, but is keeping open the option of pairing TSMC-manufactured base dies with its own DRAM, depending on what customers want. No contract has been finalised with any specific customer.

Rival SK Hynix is already there: it has partnered with TSMC since 2024, and its HBM4 base dies use TSMC's advanced logic process. Nvidia's NVHBM, unveiled last month, pushes the same way, moving the memory controller into the HBM itself behind a purpose-built base die. Samsung, for its part, announced a 56 trillion won investment, roughly $41.0bn, in July to build out HBM hubs at Cheonan and Onyang.

The numbers

• HBM eats the wafer budget
  TrendForce projects HBM's share of wafer input at the three big memory makers rising from 18% at the end of 2025 to 22% this year and 30% next.
• Fast growth still falls short
  Some analysts say even 50 to 60% HBM bit growth next year would leave supply shy of demand.
• Samsung's own commitment
  56 trillion won, about $41.0bn, pledged in July for HBM production hubs at Cheonan and Onyang.
• Server memory on a tear
  Server DRAM revenue rose 53% quarter on quarter in the second quarter, per TrendForce, as AI servers multiply.
• Micron raises the ceiling
  Its 512GB DDR5 RDIMM, unveiled on 16 September, takes a 24-module server to 12TB at 9,200 MT/s, drawing 16W against 44.2W for four 128GB modules.

Why it matters

Samsung's habit of doing memory, design, foundry and packaging under one roof has long been cited as its defining strength. AI has pushed memory specifications so far that customers increasingly want a say in who builds the logic-heavy parts, and the industry is reorganising from vertical integration into an ecosystem where customers, foundries and packagers join at the design stage. If Samsung does order TSMC base dies, the same foundry would sit inside SK Hynix and Samsung HBM4 alike, which rather changes what competition in memory means.

There is a knock-on effect for people who merely buy computers. Some consumer electronics makers warn that diverting DDR5 capacity to HBM could tighten supply for PCs and general-purpose servers, and the prevailing industry view is that DRAM prices are not falling this year or next. Budget accordingly.

Our read

These are attributed deliberations, not signed contracts, so hold the specifics lightly. But the direction matches everything else in view, from Samsung's July investment to SK Hynix's TSMC partnership, and the underlying logic is sound: once the base die becomes a custom logic chip, the foundry with the sharpest logic process gains leverage no matter whose logo is on the DRAM. For anyone tracking AI hardware costs, foundry choice inside memory is now a competitive axis worth following, and if you spec servers for a living, assume memory stays expensive.

What to watch

• A named customer.
  Any confirmed contract pairing TSMC-built base dies with Samsung DRAM turns deliberation into strategy.
• HBM4 qualification.
  How Samsung's in-house 4nm base die fares with major accelerator customers against TSMC-based rivals.
• The US angle.
  SK Hynix is reportedly in contact with Intel about using its new Ohio fab for American production.
• The next wafer count.
  Whether TrendForce's 30% HBM share projection for next year moves again.

Discussion spark: If HBM4 turns memory into a foundry game, is Samsung's famous one-stop model now a millstone rather than a moat, and does TSMC quietly win whichever way Samsung jumps?

Independent WittyWires tracker for public updates about TSMC. Not affiliated with or endorsed by TSMC; this is not an official account.