BACKGROUND

A Schottky diode is a semiconductor diode formed by the junction of a semiconductor and a metal. The metal-semiconductor junction creates a Schottky “barrier,” The metal forms the diode's anode, and the semiconductor forms the diode's cathode. As such, forward current (when the diode is forward biased) is from metal/anode to semiconductor/cathode. The Schottky barrier results in relatively fast switching and low forward voltage drop as compared to a semiconductor-semiconductor (p-n) junction. The forward voltage drop of a Schottky barrier may be in the range of, for example, 150 to 450 mV, The reverse recovery time of a Schottky barrier (when the diode switches from the conducting to the non-conducting state) is significantly lower than for a p-n junction. Because of the relatively low forward voltage and fast switching speed of a Schottky diode, Schottky diodes are often used in applications such as voltage clamps, transistor saturation prevention, power systems to prevent, for example, batteries from discharging through solar panels at night, rectifiers in switching voltage regulators, sample-and-hold circuits, and other applications.

Because of the low forward voltage of a Schottky diode, Schottky diodes also are characterized by higher reverse leakage current than p-n junctions. Reverse leakage current is the current that flows through the Schottky diode when the Schottky diode is reverse biased. The electric field around the metal-semiconductor interface of a Schottky diode is relatively high due to the sharp edges of the Schottky contact, and reverse leakage current is proportional to the electric field. As such, a higher electric field means higher reverse leakage current of a Schottky diode relative to a p-n junction.

SUMMARY

In one example, a method includes forming first and second trenches in a semiconductor substrate. The method further includes filling the first and second trenches with polysilicon. The polysilicon is oppositely doped from the semiconductor substrate. A Schottky diode is created by forming a Schottky contact on the semiconductor substrate between the first and second trenches. The method also includes forming an anode electrode for the Schottky diode. The anode electrode is formed on the Schottky contact and coupled to the polysilicon in the first and second trenches.

