Is there any rule for no. of contacts in case of MOS capacit

[rajesh13]

Is there any rule for no. of contacts in case of MOS capacitors. If yes, what is the actual phenomenon which is taking place in case of MOS as capacitor (source/drain/bulk are shorted together and act as one terminal & the other terminal of CAP is gate).
Is this related to some reliability issue.

 

[sunking]

Re: Is there any rule for no. of contacts in case of MOS cap

As normal, no rule for it.
But you should add more contacts for low res.esp when there is a big current.

 

[rajesh13]

Re: Is there any rule for no. of contacts in case of MOS cap

As normal, no rule for it.
But you should add more contacts for low res.esp when there is a big current.

But the TSMC 0.13u process restrict the no. of contacts on MOS as capacitors. The no. of contatcs are dependent on the GATE OXIDE area. More the Gate Oxide area, more the contacts you can place.

 

[sunking]

Re: Is there any rule for no. of contacts in case of MOS cap

Sorry for a mistake because I dont understand you question clearly.
Yes, no contact allow to place on MOS gate avoid to destroy the thin gate. the layout is same as MOS.
And it is better to place more contact for low res.
So the rule is reasonable.

 

[brain79]

Re: Is there any rule for no. of contacts in case of MOS cap

the only rule i know about contacts is its size and distance, so if you don't brake this rule, you can add as much as tou want watching carefully the compromise low res vs capacitance

 

[rajesh13]

Re: Is there any rule for no. of contacts in case of MOS cap

I think it has something to do with the fabrication of contacts on Poly.

 

[omsi]

hi,
i think there no rule like no of contacts.
but in analog we use minimum of 2 contacts to overcome the process variations.

 

[rajesh13]

Re: Is there any rule for no. of contacts in case of MOS cap

If you put more number of contacts then the cap value can change. ( This is seen
in the 65nm & 45nm technology, where the oxide thickness is few molecules thick)

 

[yaxazaa]

Re: Is there any rule for no. of contacts in case of MOS cap

the contact to contact rule is the only rule as I know.