Well and Substrate Taps Substrate must be tied to GND and n-well to VDD Metal to lightly-doped semiconductor forms poor connection called Shottky Diode Use heavily doped well and substrate contacts taps GND n+ n+ p+ p+ n+ n well p substrate substrate tap well tap Digital IC 6Digital IC Well and Substrate Taps • Substrate must be tied to GND and n-well to VDD • Metal to lightly-doped semiconductor forms poor connection called Shottky Diode • Use heavily doped well and substrate contacts / taps n+ p substrate p+ n well A Y GND VDD p+ n+ substrate tap well tap n+ p+ 6