How to get metal spacing rules in skill

Hi Amar,

I might be wrong but surely the layer is "M1" regardless of the purpose?  I would expect "M1" rules to apply to all purposes of "M1". What do you mean when you say "... but it is not applicable when the layer purpose came into consideration." ?

Regards,

Lawrence.

Lawrence is right (as you would expect ;-> ) and there's only limited support for purposes in technology rules - typically for implementation of voltage dependent rules. This is in OA, at least - you didn't say which version you were using.

Regards,

Andrew.

Hi Lawrence,

Hi Andrew,

Thanks for your reply.

Am using cadence 6.1.6 version(OA database).

We know that the spacing differs between layer to layer.Similarly it differs between purposes also.

Suppose ("M1" "drawing") edge  to ("M1" "drawing") edge spacing is 0.07

But ("M1" "dummy") to ("M1" "dummy") spacing might be different.....like 0.09.

So the spacing actually depends upon the layer purpose also(depend upon the technology).

My script returns the spacing between "M1" layer only(0.07)...idk what purpose it is taking because that command "techGetSpacingRule" doesnot allow to take any purpose name.

So is there any command where i can give the layer name as well as the layer purpose also as input?

Hi Amar,

I could be wrong but I believe that essentially all purposes of "M1" are treated the same from a spacing constraint standpoint. In the tech file I think it is possible to write things in terms of a specific layer-purpose combination in places where it may be supported, but you would have to always use layer-purposes as opposed to just using the layer name, plus I don't think it is supported for what you are requesting.  In other words, in the tech file M1_drawing is treated the same as M1_dummy and vice-versa for a spacing constraint.  Having said this I've not investigated this or tried things out in a tech file.  I have worked on different purposes being treated differently for connectivity, but things like viaLayers section of the layerRules tech file construct support that (definitely, I've used that).

If the constraintGroups( spacings() ) section supported different spacings for different purposes of the same layer, it seems that the techGetSpacingRule() command doesn't support reading a specific layer-purpose anyway... Where did the notion that it is supported come from?

Not sure what you can do other than to contact Cadence and get a definitive response, but my guess is that it is not supported.

Regards,

Lawrence.

Hi Lawrence,

I have some technologies,where am finding the spacing difference between purposes while doing layout.

Am not sure if the tech file is modified manually or the drc file is modified.But now am pretty sure that in the original tech file, the spacing between purposes are unique according to you.I don't know how i can get those modified spacing rules, but hopefully i will be able to find some solution.

Anyway many thanks for clearing this doubt.

Amar Kumar

Amar,

I suggest you dump the tech file. I think you'll find that there aren't any purpose-specific spacing rules in there. I'm pretty certain it's not legal syntax to specify the rules for different purposes. The special case is voltage dependent rules, but even then it's specified in a special way - see 

You may have different rules in some DRC rules perhaps, but not in the tech file. Since the tech file doesn't support it, having the SKILL API support it wouldn't make sense either.

Regards,

Andrew.

Hi Andrew,

Now I got a clear picture regarding this.Thank you for your support and help.

Amar