MIM cap bottom plate capacitance value

[viperpaki007]

Can anybody tell me that what is the aproximate value of bottom plate capacitance of metal insulator metal capcitor. I heard from somewhere that mim cap bottom plate capacitance is approximatley 1-5% of orginal capacitance value. Is it true?

 

[skal81]

Personally I would say 10~20%.
However it depends on the process you're using, especially:
- the metal used (higher metal means lower parasitic)
- if you have shielding under the Mim (metal, NWELL or other option)
The best is to check your process info, and try some back annotation.

 

[viperpaki007]

I am using cadenece generic design kit and there is not much information about the parasitic capacitance value. I have heard that MOS caps have got 10-25% of bottom plate capacitances and mimcap are much superior to them so there bottom plate capacitance should be lower than MOS caps.
I tried to simulate the bottom plate capacitance of mim cap but the resuts showed about 30% value, which is quite big. I wonder that this value is right or not?

 

[dgnani]

Hi viperpaki

you can get an estimate by the ratio of the oxide between the plates (dependent on process) and the thickness of the inter-layer dielectric below the bottom plate (agan dependent on the process.

Roughly tens on nanometer the first, a few microns the second so order of 1% is a good rough estimate

 

[nelsonadonis]

Hello, I am using cadence design kit and UMC 90nm library to design switched capacitors for power delivery. I would like to use MIM cap. But in the library, there are lots of MIM cap choices, such as MIMCAPS_20FNW_RFKF, MIMCAPS_20F_MM, MIMCAPS_20F_RFKF : ) Do you know that is the difference among them? and What do they stand for? Thank you very much.

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Hello, I am using cadence design kit and UMC 90nm library to design switched capacitors for power delivery. I would like to use MIM cap. But in the library, there are lots of MIM cap choices, such as MIMCAPS_20FNW_RFKF, MIMCAPS_20F_MM, MIMCAPS_20F_RFKF : ) Do you know that is the difference among them? and What do they stand for? Thank you very much.

 

[viperpaki007]

you can probably check the design rule manual for your process. It will give you the detailed information about type of capacitors