Hi anil4sat,
Most Place and Route tools operate on abstract views (e.g. LEF abstraction), therefore base layers & some internal geometries will not be seen by Place and Route tool. Also if you do top level assembly outside the Place and Route tool, you may not see Alucap & RDL layers present in the design, and so the DRC errors related to them.
Please find below some violations you may see at Signoff;
1 - Latchup errors
2 - nwell, deep nwell and other base layer related DRC violations (spacing, enclosure, etc...)
3 - If you are working on a top level design, and you assemble the top level after you export design from Place and Route tool, you may see some Alucap/RDL related DRCs at Signoff (e.g. vias/bumps related to Alucap & RDL layers)
4 - If you don't do metal filling in Place and Route tool, and you check DRC at Signoff without doing metal filling, you will see metal density violations in Signoff.
5 - And others that do not fill in above categories.
I hope it helps,
BR,
Gokhan
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