I'm having a memory lapse ... what's the magic layer to use to make a

tap

to bias the substrate ?

Yes,

psubdiffcont

+

psubdiff

+

li

. There is also

mvpsubdiffcont

+

mvpsubdiff

+

li

if you want to place the tap near a nwell with 5V devices in it. The latest Magic version has tap generators in the

Devices

tab.

Since there are lots of aliases for layer names, you should be able to remember

ntap

and

ptap

(and for contacts,

ntapc

and

ptapc

).

Ack thanks Lucas & Tim.