I am learning how to make integrated circuit design in Cadence, and starting with an inverter. For the layout design, I noticed that someone aligns the pins(Vin, Vout, Vdd, Vss, etc.) to the metal layer while someone aligns them to the poly layer. Which one is correct? What is the difference between selecting different layers for the pins?
For my design, I imported the components directly from the schematic design. Yet, I don't know exactly which layer are these pins assigned to.
You can pin connect to any layer that is in the extract rules connect statement list. Those same rules say how connectivity passes from layer to layer. The only requirement for the pin layer is, that it should be poly/pin for poly/drawing, met3/pin for met3/drawing, etc.
You may also see in some kits, net naming by text-on-drawing-layer.