hybrid bonding
Beginner
A way to join two chips face to face, with copper pads pressed onto copper pads. No solder is needed, so the links can be packed very close.
Novice
A way of stacking chips by pressing their polished surfaces together so copper pads fuse to copper pads, with no solder. Because there is no solder bump, the connections can be far closer together than in older methods.
Expert
Bumpless copper-and-dielectric bonding at pitches from several micrometers down to sub-micrometer in research. It needs extremely flat, clean surfaces, and it makes testing each die before stacking, and getting heat out of the stack, harder.
Explained in AI accelerators and datacenter (Industries).