That’s crazy. I thought maybe some of the other elements used in modern semiconductors might melt first. The wiring seems like a potential problem. But before that even the elements they use in the transistors themselves could be an issue.
The wiring has lower resistance for a bunch of different reasons, so the heat has a tendency to be concentrated on the transistors themselves (which are mostly silicon, just doped).
Like I have already said in another comment, semiconductors and metals behave differently when temperature increases.
For metals the electrical resistance increases with temperature, causing a negative feedback that limits the increase of the temperature, while for semiconductors the electrical resistance decreases with temperature above a certain threshold, so once that threshold is reached positive feedback increases the temperature very quickly until the semiconductor is melted, unless there is some protection system that limits the power dissipation through the semiconductor.
That is why it is very easy to melt silicon in an integrated circuit or in a discrete device, despite its high melting point.
