A Non-Destructive Technique for High Field Characterization of Gate Insulators in SiC MOS Capacitors

摘要

In this paper we report the use of a fast ramp response technique to non-destructively determine the dielectric breakdown strength of silicon-dioxide (SiO_2) gate insulators in SiC MOS capacitor structures. Conventional low voltage capacitance-voltage (C-V) techniques do not give information regarding the high field characteristics of the MOS structure, such as the breakdown strength of the oxide layer. Using the ramp response technique it is possible to determine the breakdown strength of the gate insulator or that of the semiconductor in a non-destructive manner that is not possible using classical C-V techniques. The breakdown strength of oxide layers deposited on SiC Lely substrates by a proprietary technique indicates a large variation, which could be due to variations in substrate surface condition, non-uniformities in the deposited oxide layer or the diffusion of impurities into the oxide from the highly doped substrates.