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Design >> Mixed-Signal Design >> MIM layout queries
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Message started by Dipankar on Jun 5th, 2009, 10:25am

Title: MIM layout queries
Post by Dipankar on Jun 5th, 2009, 10:25am


Dear All,

            Need your help regarding following queries .

q1. Is it a strict "NO" to run any metal layer below MIM? (In my case MIM is between m6 and m5)

q2. If the answer to q1. is yes then is it safe to define dummy blockage layer on the top of mim to protect that area from dummy insertion by Foundry ?

q3. Is providing some shielding layer beneath MIM is necessary ? If yes then which layer ? N-well ? plz suggest ?

Title: Re: MIM layout queries
Post by ywguo on Jun 16th, 2009, 7:43pm


Quote:
q1. Is it a strict "NO" to run any metal layer below MIM? (In my case MIM is between m6 and m5)

It is a strict "NO".


Quote:
q2. If the answer to q1. is yes then is it safe to define dummy blockage layer on the top of mim to protect that area from dummy insertion by Foundry ?

Yes.


Quote:
q3. Is providing some shielding layer beneath MIM is necessary ? If yes then which layer ? N-well ? plz suggest ?

No.

Title: Re: MIM layout queries
Post by Dipankar on Jun 20th, 2009, 5:54am

Dear Sir,

             Can you please illustrate why running any other metal line beneath MIM is not a good practice ? Actually  I have m1 routing at some places beneath MIM (it's  between m6 and m5) and it does not violate drc.

Title: Re: MIM layout queries
Post by Berti on Jun 23rd, 2009, 3:42am

I think it is ok to route metal lines underneath a MIM capacitors, if you can except the increased bottom plate capacitance and risk of coupling.
But q3 was referring to shielding what you can do, but is not necessary.

The use of M5/M6 below the MIM is probability prohibited by the fab since it might results in a short in fabrication.

Regards

Title: Re: MIM layout queries
Post by Colbhaidh on Jul 21st, 2009, 4:23am

The is no Fab process limitation to routing metal beneath the bottom plate. The only concern would be coupling as mentioned before.

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