Meshing a big thin volume (~2.5 mm x 6.5 mm x 14 um)

Hi all,

I have being simulating the capacitance between different pads/terminals between CMOS chips assemblies for the last year without a problem.
Usually, these pads are 20 x 20 x 4 um and the chips assembly is ~15 um (small volume).

Now I am trying to simulate a test structure that has about the same thickness (14um) but the pads are 1.5 x 1.5 mm large.
The structure that I am trying to simulate is 2.5 mm x 6.5 mm x 14 um (its thickness is much smaller than its area) and (I think) this is making the meshing more complicated to do (even more as it is composed by different layers, going from 0.2 um to 5 um).

I have already tried to use (in just one of the simplest domains) Free Tetrahedral meshing and Free tetrahedral/quad + Sweep (controlling the distribution and trying different edges) on the boundaries.

I don't know how to proceed and that's why I am here. I would like to ask for help from this community (as I already did it before and it was super fruitful). The model is attached.

Many thanks for any help!
Cheers,
Mateus