Antenna Effect

Definition
During the fabrication of MOS integrated circuits, especially at the time of plasma etching, there will be a chance of collecting more charges at the gate and causes damage to the gate oxide layer since it is very thin. This condition is known as Antenna effect.

Antenna Violation 
The ratio of the gate area to the gate oxide area is known as Antenna ratio. Because the area/size of the conductor (gate area) will decide the magnitude of the charge collection. When this ratio exceeds a value specified in a Process Design Kit (PDK) , will leads to Antenna violation.

Click here to go to Process Design Kit (wikipedia).

Solutions for Antenna Violation
  • Metal jumpers : Break signal wires and route to upper metal layers by jumpers. Jumper insertion breaks the long wire which is connected gate and route to upper metal layer. So it becomes short and less capable of collecting charge. If the antenna violation happens at a metal layer, always use higher metal layers as metal jumper since all the lower layers are already fabricated at that moment.
  • Diode insertion : Connect reverse biased diodes near gate input where violation occurs on a net provides a discharge path to the substrate which saves the gate of the transistor. Adding diode increases the area and also the capacitance which leads to increase in delay. 



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