soft connections for well and substrate

[d-m-bailey]

Currently, extraction with magic treats well and substrate the same as metal for connectivity. This means that the following circuits will pass LVS even though the ground connection is through the substrate.

One possible solution would be to defining high resistive planes (including substrate) that only pass connectivity from a higher level and print an error/warning if more than one node tries to connect.

[d-m-bailey]

This might be a temporary method for finding these errors. https://github.com/d-m-bailey/sconnect_for_sky130_magic

[d-m-bailey]

For reference, this repo has a setup for detecting these types of errors with magic and netgen.
https://github.com/d-m-bailey/sconnect_for_sky130_magic