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Other CAD Tools >> Physical Verification, Extraction and Analysis >> how to verify wire density
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Message started by lily on Oct 17^th, 2005, 5:56pm

Title: how to verify wire density
Post by lily on Oct 17^th, 2005, 5:56pm

Hi All,

I am trying to do some analysis of the wire density after routing. I found one "verify density" function in silicon ensemble. And I tried several times but always got "CADENCE-PROBLEM-31 DISASTER..." >:(. And I couldn't find anything about it in SE manual. How should I use it correctly or is there any good tool to do this analysis?

Thanks a lot!

lily

Title: Re: how to verify wire density
Post by Paul on Oct 19^th, 2005, 12:40am

Hi Lily,

if you talk about metal density checks, I would suggest using a DRC tool (Dracula, Diva, Assura, Calibre). It may take some more of your time because you have to switch tools (I don't think you can run Assura directly from SE). I think there also is an antenna verification in SE which sometimes gives strange results. I wonder if the implementation of these tools has been improved in SoC-Encounter.

In most cases, the foundry mask shop people take care of adding dummy metal to comply with the density rules. Maybe you don't need to care too much about this (especially in the case of a standard-cell design in SE).

Paul

Title: Re: how to verify wire density
Post by lily on Oct 20^th, 2005, 2:21pm

Thanks for your suggestions. Actually I wanna get the wire density and then do some analysis based on it. With the DRC tool, can I get the report file of wire density?

//lily

Title: Re: how to verify wire density
Post by Paul on Oct 20^th, 2005, 2:29pm

Hi Lily,

The DRC tool usually does what it is asked for by the rule file. I believe most foundries specify the density per sqmm or something comparable, and that's what is defined in the rules. If you want to obtain a value for the whole chip, you probably have to write an additional rule defining the calculation on the whole chip area at once. To me this seems feasible (althoug I never tried).

If needed, please mention the tool you intend to use and I may be able to direct you to the corresponding command.

Paul

Title: Re: how to verify wire density
Post by lily on Oct 24^th, 2005, 11:45am

The PDK provided a Diva DRC rule file. I think you are right. I have to add some additional rule defining the calculation. Do you have any idea how to add this rule in the diva drc file? Thanks.

//lily

Title: Re: how to verify wire density
Post by Paul on Oct 24^th, 2005, 1:18pm

Hi Lily,

I've never used Diva, so I will have some trouble guiding you. In case I can get hands on a documentation I'll try to have a look, otherwise I'm sure somebody else will be able to help you out.

Paul

Title: Re: how to verify wire density
Post by Andrew Beckett on Oct 24^th, 2005, 2:03pm

Look at the Diva reference manual. You'll find it in your IC software installation:

<instdir>/doc/divaref/divaref.pdf

There is a section in there called drc(coverage) and this is followed by a description of geomGetCoverage(). These two sections explain how to write a coverage rule. There are examples too - it is straightforward enough.

Regards,

Andrew.

Title: Re: how to verify wire density
Post by lily on Oct 25^th, 2005, 2:34pm

Thank both you two very much!

//lily