Integrated circuit subsurface zener diode

摘要

A zener diode is incorporated into a conventional integrated circuit without changing the process. The structure employed produces a diode that breaks down in a subsurface region, thus avoiding the noise and instabilities that attend surface breakdown. An isolation diffusion is employed to make the anode and an NPN transistor emitter diffusion is employed to provide the cathode. If the emitter diffusion diameter is larger than the oxide cut used to achieve isolation predeposition and is concentric therewith, the resulting zener diode will have its breakdown region confined to under the emitter diffusion. The diode action is thereby remote from surface junction breakdown effects.