In QRC it is possible to change how substrate/well connections are made using the substrate_connection command.
With the device_list option it looks like it is possible to connect to the nearest well tap in the extracted netlist
If I add the following command to the QRC run:
substrate_connection \
-remove_contact layers "none" nets "none" \
-device_list "ngate_25od_mac" "pgate_25od_mac"
My R extracted netlist is:
XM2 io#6316 io#6319 vdd#50 vdd#48 pch_25od33_mac L=4.4e-07 W=4e-07 (etc)
XM3 io#2533 io#3160 vdd#8 vdd#48 pch_25od33_mac L=4.4e-07 W=4e-07
XM4 io#2514 io#2515 vdd#1 vdd#6 pch_25od33_mac L=4.4e-07 W=4e-07
I.e. for the nwell connections (4th terminal) all devices in the same well use the same subnet of vdd rather than the nearest well tap.
Should I get a different result with the device_list option?