Antenna effect
Beginner
Static charge that builds up on long wires while the chip is made. It can zap the chip’s tiny switches.
Novice
Damage that can happen during manufacturing. While metal layers are etched with electrically charged gas (plasma), a long wire connected only to a transistor’s input collects charge that can break through the transistor’s very thin insulating layer. Antenna rules limit how much wire can connect to one input before a protection measure is needed.
Expert
Antenna rules limit the ratio of metal area connected to a gate to the gate area, per layer and cumulatively up the stack. Fixes: a protection diode, jumping to a higher metal layer near the gate (so the long segment isn’t connected until later), or splitting the net. Routers repair most violations; signoff re-checks the final layout with the foundry’s rules.
Explained in Signoff (Design Flow).