It was never the lithography

Ask someone what constrains AI accelerator supply and the answer will almost always involve extreme ultraviolet lithography: the tool count, the export controls, the single supplier. It is a good story. It has not been the binding constraint since 2023.

An accelerator is a logic die integrated with high-bandwidth memory stacks on a silicon interposer. The logic die comes off a leading-edge wafer line that has been running with available capacity for accelerator-class parts throughout the period. The integration step — advanced packaging — has been at capacity continuously.

The reason attention went elsewhere is measurability. Lithography tools are individually enormous, individually expensive, individually tracked in shipment disclosures and individually named in export control instruments. Packaging capacity is diffuse, less well documented and harder to count. The analysis followed the data availability.