barrel effect in metal-metal capacitors

[Humungus]

capacitors

Hi,

Does anybody know what the barrel effect is in large metal-metal capacitors?

I have in hand a layout checklist and this is mentioned as being some kind of issue.

Do you have any information or description of it?

Thanks.

 

[erikl]

Does anybody know what the barrel effect is in large metal-metal capacitors?

I'm not quite sure, but I guess the optical barrel distortion effect is meant, which tends to reproduce large rectangular structures into barrel-like geometries - depending on the lithography equipment used. This could increase the intended capacitances a little bit, the effect increases non-linearily with increasing structure size. If this should be a pb., compose all caps from (integer) numbers of smaller caps of the same size - which is good practice anyway.