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How to fix layers after changing layer numbers in the technology file

Sheppy

Hi,

This is what I have done:
I have updated layer number information in the technology file in the sections TechnologyFile->layerDefinitions->techLayers and TechnologyFile->layerRules->functions. The reason for changing the numbers is that in the original technology file, the layer numbers did not match the actual gds2 numbers. So exporting a layout to gds2 resulted in a not compatible database.The second reason is that I had to change layers because Virtuoso crashed due to inconsistent layer name-number mapping in the technology file, see post Home > Community > Forums > Custom IC Design > Virtuoso crashes when trying to instantiate a stacked Via (community.cadence.com/.../34766).

But then I ran into a problem: after the recompiling and attaching the new technology file, when I open an existing layout layers have changed color/fill or are completely invisible. It looks like Virtuoso does not store the layer purpose pair (lpp) as MET1:drawing, but rather as the assigned numbers, like 19:0. When you reassign the numbers to a different lpp name it will get the display information of that new name as specified in the display.drf file. If a layer had a number like 22:0, and this number is not assigned to any layer in the new technology file, it is completely invisible.

What I see is that all shapes in a layout have the layerNumber stored, and only a few have the layerName stored. When I do the following:
foreach( shape cv->shapes printf( "%L - %L\n" shape->layerName shape->layerNumber ) )
I'll get the following output (example after updating the technology file):
nil - 107
nil - 55
nil - 107
"METTOP" - 31
"VIAT" - 30
"METTOP" - 31
This looks to me that Virtuoso stores only layer number information (all shapes have the number, not all have the name) and when asking for the layer name, it simply matches the number to the name in the technology file. If a layer number is not associated to a name, it reports nil. So the name is not stored.

My questions:
1. How do I fix the layout after changing the layer numbers in the technology file?
2. Is it possible to configure Virtuoso so that is stores the layerName instead of the layerNumber?

If I have to roll-back all changes (giving each layer it's original, wrong, layer number again) I might end-up in a situation that I am unable to instantiate a stacked via, since Virtuoso will crash. How can I disable the stacked via option?

Thanks in advance.

With kind regards,

Sjoerd

Parents

  • Hi Ted,

    Thank you too for the reply.

    When I write p-cells (all pure SKILL), and add shapes in certain layers, I refer to the layers as follows: list("MET1" "drawing"). Referring to the original problem stated in the original post, all p-cells generated like this were still working fine. All other p-cells (generated by a p-cell made using the standard graphical p-cell editor) were corrupted after changing the layer numbers.

    Does this mean that:
    - graphical p-cells have th elayers stored as numbers
    - p-cells which are purely SKILL-based will always be working fine, thus the safest option when creating p-cells?

    If the second is true, this would be a huge incentive to never use a graphical p-cell editor.

    Kind regards,

    Sjoerd

Reply

  • Hi Ted,

    Thank you too for the reply.

    When I write p-cells (all pure SKILL), and add shapes in certain layers, I refer to the layers as follows: list("MET1" "drawing"). Referring to the original problem stated in the original post, all p-cells generated like this were still working fine. All other p-cells (generated by a p-cell made using the standard graphical p-cell editor) were corrupted after changing the layer numbers.

    Does this mean that:
    - graphical p-cells have th elayers stored as numbers
    - p-cells which are purely SKILL-based will always be working fine, thus the safest option when creating p-cells?

    If the second is true, this would be a huge incentive to never use a graphical p-cell editor.

    Kind regards,

    Sjoerd

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