Re: Antenna check
Antenna errors occur when a large metal structure is connected to a gate. When the metal is etched in the fabrication a large amount of charge might be induced in the metal. This can cause the gate to break if there is no discharging path for high voltages (like a drain/source or a reversed diode).
Antenna errors can be fixed by adding a reversed diode connected to the metal wire causing the problem. A N+ doped nwell contact will function as a reversed diode if it is connected to the substrate.
Ref: TSEK01 - VLSI Deisgn Project 2006, Third Edition, Rev. 2005, Linkoping University, Sweden