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How to generate overlapping layers in the layout for an existing layer?

ssram

Hi,

How to generate overlapping layers in the layout for an existing layer? For example, if there is an M5 present, i would like to have M4, M5 & M6 blocking layers overlapping on top of the existing M5. I do not want to use the layer generation method since its bit complicated, would be great if i could just do this by the push of a button.

Usually this is used to add dummy blocking layers on top of critical signals and the signal is not always just in one single metal layer, its mostly routed in different metal layers. So, this option should work on the selected layers rather than on just one metal layer. There are a lot of such things i guess Cadence should consider having it in-built so that we don't have to look for a script every now and then. But for time being, i would appreciate if someone could help me out here with a solution.

Thanks

Sooraj

  • Hi Sooraj,

    Given that this is very specific to what you want to do, having a single button press is a bit of a tall ask. There's the layer generation as a UI - which is simple enough to use. There's also abstract generation (although this is more about adding blocking layers to the current cell) - but that needs a little bit of setup. There's cover obstructions which allows you to mark the whole prBoundary as being blocked for particular layers. 

    Or you could write some SKILL code to do the specifics of what you want (particularly using the new abe functions I mentioned in your other post).

    Regards,

    Andrew.

  • Hi Sooraj,

    from reading your original post I have the feeling that you will have more success by creating a constraint for your net (VLS-XL).

    Here are 2 that might help:

    A co-axial shield constraint: This will create shield geometries left, right, above, below your net if you use the Wire Editor or autorouter.

    A Process-Rule Override constraint: If you don't want extra geometries you can create a P.R.O. constraint.

    No blockages, or layers are generated, but the autorouter would route other nets away from your critical net.

    Check the documentation, but a PRO with larger spacings defined for all layers plus a layer-layer spacing of 0 for M1-M2, M2-M3 etc to prevent different layers overlapping your net may do what you need.

    But don't forget, it may not be possible to route the rest of your nets if they cannot cross over your net. It depends on your floorplan and number of routing layers.

    Colin

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