Design, Fabrication, and Characterization of Ni/4H-SiC (0001) Schottky Diodes Array Equipped With Field Plate and Floating Guard Ring Edge Termination Structures

Abstract

In this paper, a through process for a commercial fabrication of a Schottky diodes array on thick epitaxial (50 $\mu{\rm m}$ ) 4H-SiC (0001) is presented. Nickel was used as a Schottky contact, while a tri-layer of Ti/Pt/Au was considered for ohmic contact metallization. An oxide field plate edge termination and floating metal guard ring was integrated simultaneously in each device structure. Moreover, to improve the device reliability, an optimum thickness of field plate (composite layer of thermally grown oxide and plasma enhanced chemical vapor deposition oxide) was introduced. The process-induced carbon-oxides contamination was eradicated by vacuum annealing at a mild temperature. The critical values of device parameters, such as leakage current, breakdown voltage $(V_{BV})$ , Schottky barrier height $(\phi_{B})$ , ideality factor $(\eta)$ , and epitaxial doping concentration $(N_{D})$ , were obtained from experimentally measured current–voltage $(I{\hbox{--}}V)$ and capacitance–voltage $(C{\hbox{--}}V)$ characteristics. The data revealed that $\phi_{B}$ , $\eta$ , $V_{BV}$ , and reverse leakage current are 1.34 eV, 1.21, ${>}{\rm 800}~{\rm V}$ , and 900 pA (at ${-}{\rm 100}~{\rm V}$ ), respectively, which suits most commercial aspects.