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efabless / skywater-pdk-libs-sky130_fd_sc_hs

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DRC error for designs containing dlygate4sd3_1 #14

Open MichaelBell opened 5 days ago

MichaelBell commented 5 days ago

When using the sky130_fd_sc_hs cell library with OpenLane2 (Tiny Tapeout based flow), the Magic DRC check fails due to errors in sky130_fd_sc_hs_dlygate4sd3_1 cells.

If that cell is added to libs.tech/openlane/sky130_fd_sc_hs/drc_exclude.cells then the flow completes and DRC passes.

An example of a failing design can be found here: https://github.com/MichaelBell/tt09-factory-test/actions/runs/10845419808

The rule causing the error is Diffusion contact to gate < 0.055um (licon.11).

We believe the problem may be that an exception to this rule for standard cells isn't being applied to this particular cell.

RTimothyEdwards commented 3 days ago

I will need to take a look at this. All other standard cells---or at least the ones in the HD library---are marked with the "standard cell ID" layer 81:4, which is what magic uses to make sure the standard cell exception is applied to the DRC rule. I don't know if it's this cell specifically or the whole library that is missing the layer.

RTimothyEdwards commented 2 days ago

Okay, this appears to be my omission and I will correct it. Meanwhile, this DRC error can be ignored.