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Prevent Net Extraction for Shapes

PK202501238151

Hi,

is there a way to prevent net extraction for specific shapes? I'm generating layouts with external tools and mark the with `lxStickyNet = t` to prevent their nets to change by the extraction. However, there are also shapes that have no net assigned, and they change connectivity, even though lxStickyNet is set.

Thanks, kind regards,

Patrick

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  • Andrew Beckett

    Patrick,

    I'm not sure of the answer (without doing some additional research), but my first question is why you would want shapes on connectivity layers without nets to continue not having nets (I understand for the scenario where you have pre-assigned the net yourself; not so much for the net-less shapes)?

    Andrew

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  • Andrew Beckett

    Patrick,

    I'm not sure of the answer (without doing some additional research), but my first question is why you would want shapes on connectivity layers without nets to continue not having nets (I understand for the scenario where you have pre-assigned the net yourself; not so much for the net-less shapes)?

    Andrew

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  • PK202501238151
    in reply to Andrew Beckett

    Hi Andrew,

    fair question. I'm auto-generating power grids, so I need net information for shapes, as targets for placing vias to power shapes. Among these targets there are guardrings with metal 1 ring shapes. I generate these guardrings and set the top and bottom segments to the power nets (e.g. one guardring is on vdd). If the extraction runs, the nets are also assigned to the left and right segments. As they are not in the preferred routing direction for the power grids, the via generation on these sometimes causes DRC issues. Not assigning the left and right segments would be a work-around for this (although granted, not a good solution).

    Patrick

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