Need help with Minimum Routing Layer

[shipherd]

Hi,

I have a set of standard cells which all of them have Pin Shapes of Metal 3 and it requires that the minimum routing layer must be Metal 3.
I have tried set_routing_layers, and indeed OpenROAD started to route on Metal 3, but still I have found some Pins were accessed through the "Metal1-Via1-Metal2" cuts.
How to prevent the tool from using the layers that are below Metal 3? e.g., Do NOT use Metal 1, Via 1 and Metal 2.

Thank you.

[maliberty]

Is it illegal to access them that way? If those shapes are truly unusable they should just be obs shapes.

[shipherd]

I have found one solution to this problem - set it to extract the signal nets on M3 only if using Abstract in the Extract window.
Thanks for the comments by the way @maliberty .