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using auto-vias through SKILL

Leonardo Vinci

I have a list of bBoxes of path shapes of 0.05um width (M1, M2, M3 overlapping/stacked on each other) in my current hierarchy. I have dbIDs of shapes as well. I tried to use function "dbCreateViaShapeArray" but it requires calculations of how many vias we can place(and this could change upon different lengths of the overlapping paths, i could calculate the length of path by subtracting starting y and ending y from their bBoxes, but still it is not generalized for different path lengths).  And also it is not giving equal enclosures of both the ends of the paths. 

The requirement here for me is to use auto-via function somehow on these overlapping shapes somehow through SKILL code because auto-via is giving me required proper results. 

So, how to use auto-via on these overlapping path shapes to get the desired result.  

  • Quek

    Hi Leonardo Vinci

    Starting from IC617, you can use functions such as viaGenerateViasAtPoint to automatically create vias. It is the SKILL equivalent of autovia function. Please see $CDSHOME/doc/sklayoutref/sklayoutref.pdf for more details.


    Best regards
    Quek

  • MatthewLove
    in reply to Quek

    Hi Quek,

    Which version are you using? I'm on 617 and that function isn't in the document you specified or the virtuoso help docs in general.

  • Andrew Beckett
    in reply to MatthewLove

    It was added in IC617 ISR7 - i.e. subversion IC6.1.7-64b.500.7 (and added to the documentation then).

    Regards,

    Andrew.

  • Leonardo Vinci
    in reply to Andrew Beckett

    "viaGenerateViasAtPoint"  I use this function(to stack Via1 and Via2) and it does fine only problem is it takes some 15 to 20 seconds to put vias over just 5 metal shapeswhich are less than .5um in length and .032um of width. why is this function so slow?  

  • Quek
    in reply to Leonardo Vinci

    Hi Leonardo

    If you see the same slow performance using IC617-ISR18 (or IC12.3-ISR18), it would be good if you can file a case to your local Cadence support so that they can investigate the issue.

    Best regards
    Quek

  • Leonardo Vinci
    in reply to Quek

    I am using Ver. 12.3 ISR14. Cant find local cadence support. :/ 

  • Andrew Beckett
    in reply to Leonardo Vinci

    You could always try support.cadence.com or the "Support" link at the top of this page:

    BTW, I did some searching around the time Quek responded and only found one report of an issue with slowness with this function, but it turned out that the user found his own mistake (in his code) and so it wasn't something we needed to fix. Could still be a problem of course, but we'd need to see the details of the problem.

    Regards,

    Andrew.

  • Leonardo Vinci
    in reply to Andrew Beckett

    I have used viaGenerateViasAtPoint(), viaGenerateViasFromShapes() and viaGenerateViasInAr​ea() interchangeably for the same task, but i am still facing issues and to my surprise, the time required by the task using these three functions is same, 15-20 seconds. I have contacted support too, but not much help. 
    Is there any other way of putting auto vias from bBoxes, or shapes or area, or any other thing? 

    Regards, 

    Leo 

  • Quek
    in reply to Leonardo Vinci

    Hi Leo

    Do you have a case or CCR number from your local Cadence support?

    Best regards
    Quek

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