Trench MOS Barrier Controlled Schottky Rectifiers

Abstract

Device structures for reducing the electric field at the Schottky contact were discussed in the previous chapters by incorporation of either a P-N junction or a metal located within trenches. The suppression of the electric field enables significant reduction of the leakage current under reverse blocking operation. In this chapter, yet another approach to suppressing the electric field at the Schottky contact will be described. This approach utilizes a metal-oxide-semiconductor (MOS) structure incorporated within trenches etched around the Schottky contact. The depletion of the region between the trenches under reverse bias operation creates a potential barrier under the Schottky contact and screens it against high electric field in the bulk of the semiconductor drift region. This device structure is referred to as the ‘Trench-MOS-Barrier controlled Schottky (TMBS) rectifier’ structure1. As in the case of the JBS and TSBS rectifier structures, the depth of the MOS structure used to form the potential barrier is small when compared with the total drift region thickness. In this device concept, the MOS structure is used to suppress the electric field at the Schottky contact but not used to shape the electric field profile in the drift region.