Basic question about metal thickness in interdigitated capacitors

Hi all,

looking at various models, I always found that the thickness of metal in microwave interdigitated capacitors is not part of the equation. Is it because typically the metal thickness is so thin that only finging fields are relevant? What if my thickness is in the same order of magnitude of fingers spacing and width?

I am a guy coming from the low-frequency side and to me it looks like it should somehow be part of the game.

Thank you in advance for any advice!

M.