MIM capacitor voltage dependence

[Sadegh.j]

mim cap shield

Hey

How is a MIM capacitor manufactured?

 

[salem_eng1]

mim capacitor

MIM Cap (Metal Intrinsic Metal capacitor)
is a metal to metal capacitor manufacture by making two metal very narrow to each other to increase the capacitance.

In manufacturing the MIM cap have two special metal layers for it and this two metal layers mainly be founded in the upper higher layers.

Ex: MIM cap in TSMC 0.13um RF technology is founded under the metal-7 between two special metal layer very narrow to each other and manufactured especially for the MIM cap.

The following picture describe how the MIM-Cap is manufactured:


Not that: The 2-metal of cap are connected to the metal-7 to connect them to any other device in the design but this connections is not plotted here for the simplicity.

 

[Sadegh.j]

Re: MIM capacitor

I was told that the bottom layer is a bit bigger than the top one, is this correct, if yes, could you tell me why?

 

[freelancer]

Re: MIM capacitor

I think
first ,to the circuit design ,there always are electromagnetic fields lekage in the fringe of the capacitor,and influnce the signal lines below ,so making the bottom plate a little bigger can shield this field ,protect the signal path below.
second ,to manufacture ,there always are some misalignment in real manufacturing ,so, to avoid the misalignment of the two plae induced capacitance disceptance and get the precise capacitance we wanted ,we can make the bottom plate a little bigger and the top plate the excise area to cancel the misalignment and get the right capacitance.
Above is my personal consideration ,may be wrong!thank you for correcting!

 

[Sadegh.j]

Re: MIM capacitor

I have also heard the first one, the second one is quite new.

Cheers

 

[kunaldekate]

Re: MIM capacitor

How do we find capcitance vs voltage characteristics
by which formula
capacitor refers to mim structure and dielectric as silicon nitride

 

[erikl]

Re: MIM capacitor's voltage dependency

How do we find capcitance vs voltage characteristics

By first approximation, MIM caps aren't voltage dependent. Real MIM caps, however, show some (small) voltage dependency, and their voltage coefficient (VC) usually is documented in the fab's PDK.