A bit late to the party, but still want to share some of my thoughts on the rumor that TSMC may enter 3D DRAM at NVIDIA’s request: (1) What does “3D DRAM” mean here? The rumor leaves that unclear. If it means a 3D structure built during front-end fabrication to increase storage capacity per unit of die area, I would see NVIDIA’s motive as backing another DRAM supplier to expand wafer supply and push down today’s high prices. That seems a weaker fit for TSMC’s customer-specific foundry model, so I find this scenario less likely. (2) The rumor said the 3D DRAM project would be led by TSMC’s VP of advanced packaging technology development, which means that 3D DRAM could also mean vertical stacking during packaging, just like HBM. NVIDIA’s HBM base dies are already moving toward custom designs manufactured by TSMC. The three major DRAM makers still produce the DRAM dies and handle stacking and packaging. Asking TSMC to take over those two steps would basically mean asking it to manufacture HBM in direct competition with the DRAM makers. Again, I would see the motive as expanding supply to lower prices. This also seems a weaker fit for TSMC’s model, so to me the claim doesn’t work as well. (3) Another possibility is the kind of 3D DRAM in d-matrix’s “Raptor” inference chip, presented at this year’s Hot Chips. Like HBM, it uses vertical stacking during packaging. But while current HBM pairs a custom base die with DRAM dies that retain a standard design, Raptor’s DRAM dies themselves are highly customized, removing the need for a separate base die as the data interface. Both the DRAM design and stacking architecture are highly customized, making this inherently a made-to-order business. The chip designer leads the DRAM design, just like d-matrix does for Raptor, while TSMC provides fabrication and stacking services. Competition with DRAM makers would be more indirect, and the impact on them would not necessarily be negative. If NVIDIA is asking TSMC to manufacture this kind of custom 3D DRAM, that fits TSMC’s business model much better. Personally, I find this scenario more plausible. (4) Whatever “3D DRAM” means, TSMC’s business model is significantly different from that of DRAM makers. If TSMC do enter the market, I would still expect it to manufacture against customer orders. It would not bear the same inventory sell-through risk as DRAM makers, so I would expect much less dramatic profit swings.