Building a few houses isn’t enough to make a neighborhood. You also need to build the roads and sidewalks to connect them.

Same with an integrated circuit. You can stick a billion transistors on an IC, but they are useless if you cannot also connect them.

That is what interconnects are for. They are wires for transmitting the electrical signals between transistors and other circuit elements.

For over 30 years, we used to make these interconnects and their insulating layers from aluminium and silicon dioxide, respectively.

But by the late 1990s, it became technically necessary to use new materials. Big technology transitions are opportunities for certain companies to pull ahead of the rest. In this case, that certain company was TSMC.