Zener diodes are used in a number of different applications. For example, a Zener diode may function as a shunt that prevents voltages across some other electrical circuitry configured electrically parallel to the Zener diode from exceeding a breakdown voltage of the electrical circuitry when the voltage exceeds the reverse bias breakdown voltage of the Zener diode. It is desirable for Zener diodes to exhibit a stable and reliable reverse breakdown voltage with minimal leakage current. However, achieving this objective is particularly challenging when integrating fabrication of the Zener diode into a fabrication process optimized for other devices on the semiconductor wafer (e.g., logic transistors and the like). While it is possible to add process steps that are optimized for the Zener diode to the fabrication process, this undesirably increases the fabrication costs. Furthermore, when the process steps optimized for other devices on the wafer are used to fabricate a Zener diode, the functionality and/or performance of traditional Zener diode structures may be constrained by the doping levels of the implants for the other devices on the wafer, which, in turn, limits the range of achievable breakdown voltages. Additionally, process variations attendant to fabricating traditional Zener diode structures may further exacerbate the effects of fabricating the Zener diode structures using process steps that are not tailored to the Zener diode.
USPTO Backgrounds
USPTO Backgrounds