Micron dismisses 4F-squared DRAM as CXMT presses ahead — why Samsung, SK Hynix remain divided

The DRAM industry is undergoing a rare architectural schism — not a roadmap debate, but a forced bifurcation of parallel technology stacks under geopolitical fragmentation. Micron's rejection of 4F² is a calculated move, not a capability gap: with advanced lithography access constrained, 6F²'s capacitor scaling hits a hard yield ceiling, making 3D DRAM the only viable escape from planar microscaling dead-ends. CXMT's bet on 4F² commercialization is, in essence, trading process complexity for bit density under DUV multi-patterning constraints — viable, but with a materially steeper cost curve. The supply-chain ripple is structural: 3D DRAM will exponentially amplify demand for high-AR etching and ALD, while 4F² continues to pull multi-patterning lithography and metal interconnect. ASML, Lam, and TEL order books will restructure along customer blocs. Samsung and SK Hynix's hedging is not indecision — it is a pre-HBM4 strategic positioning play. Whoever locks in the 3D DRAM packaging interface standard first captures pricing power over next-gen AI memory. 12–24-month outlook: the two paths will not converge. They will solidify into two independent ecosystems. Micron's first-mover window is roughly 18 months; if CXMT ships 4F² in 2026, it will anchor pricing in the mid-low segment, forcing Samsung to shift conventional DRAM capacity further toward HBM and accelerating profit migration toward packaging and interface layers.