regarding physical design

[smith_kang]

hi
can anybody tell me about Antenna Effect in ASICs.

regards

 

[arunragavan]

wot do u excatly mean by antenna effects on ASIC.. do u mean microwave raditation effects.? or effects of radiation on semiconductors?

with regards,

 

[stormwolf]

Antenna effect in asic is for produce, at produce charge will collect in asic and it will damage for asic,
so we should change large metal to small metal to reduce charge collect by metal.

 

[eda_wiz]

Antenna effects are long floating interconnects that act as temporary capacitors during the metalization process. Because a conducting path to ground does not exist at the time of metalization, a random discharge from the floating nodes can cause permanent gate oxide damage.

 

[Vamsi Mocherla]

Antenna effect on a gate of a transistor exists because of the metalization process. The metals have free moving charges after Plasma etching. Usually the thumb rule is when the area of the metal connected to the gate is more than 1000 times to the polysilicon gate area, then huge voltages occur on the gate. This will break down the oxide.

The remedy is to cut the long metal and bridge it with a higher metal in between or provide a leakage path in form of antenna diodes

 

[omid219]

Does back-end tools prevent this phenomena? where can I find more information on this.

thanks

 

[Vamsi Mocherla]

definately, they do so....All the DRC rule decks will have a provision for Antenna check. So, the foundry should provide them.....Also, Digital PD tools will have provision for antenna checks

 

[Raptor]

Antenna is a large, charge-carrying conductor attached to a small gate.
During the ion etch stage of fabrication, electrical charge builds up on conductor layers (poly,contact/via, metal). This charge, through electrical stress, leads to degradation of the gate and in extreme cases may destroy the transistor entirely

There a lot of DRC checks to detect antenna effects, and to avoid this a diode(so that there is path to ground through diode) or jumper(so that the area of metal is small ) is used.