Antenna Effect - Antenna Rules

Antenna Rules

Antenna rules are normally expressed as an allowable ratio of metal area to gate area. There is one such ratio for each interconnect layer. The area that is counted may be more than one polygon —it is the total area of all metal connected to gates without being connected to a source/drain implant.

• If the process supports different gate oxides, such as a thick oxide for higher voltages and a thin oxide for high performance, then each oxide will have different rules.

• There are cumulative rules, where the sum (or partial sum) of the ratios over all interconnect layers sets the limit.

• There are rules that consider the periphery of each polygon, as well.

Before signing-off a physical design/layout for fabrication, the Antenna Rule Check is therefore performed.