MIM caps CMOS process - Quality factor/Series resistance - Differences mod/meas

Hi!

Situation:

I recently compare series resistance of MIM capacitors from model with measured data. The results shows enourms descrepance between the series resistance model/Measurement.

I have atached a picture showing the results model and measurement data.

Otherwise in the smith chart everything looks fine. All parameters fits the measured data.But not the quality factor and series resistance.

The measurements were made using a probe station and network analyzer.
Normal setup... 1-port to ground

By the way im working with 0.18um CMOS process.

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So i have 3 questions:

1) The model contains a very low series resistance for MIM caps...aproximally 20m Ohm is that the usual value for a series resistance of MIM caps?

2) I have compared the series resistance of MIM caps with other tecnhnologies and the series resistance for a 1pF MIM capacitor goes around 1.5/2 Ohm. Is that the usual value for series resistance?

3)What could be wrong? Model? Measurement?
For low values of series resistance the equipament cant measure correctly the series resistance of MIM caps? Is that possible?


Best regards

Canosa