You need to connect a VIA from nwell to the appropriate metal you tend to use. to check the correct via if you don't know I advice you to use LVS test.
No: From nwell (or any other silicon surface) you need a contact opening (not a via) to metal1 . In ICs, vias are ties between different metal layers only. Simply a naming convention.
No: From nwell (or any other silicon surface) you need a contact opening (not a via) to metal1 . In ICs, vias are ties between different metal layers only. Simply a naming convention.
Need to check your layout design rules. Some processes with dnwell require some type of termination ring around the edge of the dnwell. It is all dependent on the technology