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Capacitance simulation with 3D expansion

Question asked by benji627 on Mar 29, 2007
Latest reply on Mar 29, 2007 by ALEPEREZ

I try to simulate capacitance effects between two metal layers electrodes, in Al 0.8µm, with an oxide of 0.25µm per example. Epsilon same everywhere.

I use RFDE 2005A,
- in No Expansion mode (sheet conductor), no problem, C extracted value is correct.
- in 3D  DOWN, correct too.
- in 3D UP, incorrect value, lower almost the half than expected !

I tried many configurations, changing conductor thickness or oxide thickness, the 3D UP is always false.

If I look RFDE Documentation,I can read in 3D expansion chapter:"The thickness values of the dielectric layers in between the metal are not changed,which will preserve the capacitance value between the two conductors lying on top of each other in the substrates."

What's wrong ?