Demonstration of a 10-kV Class Waffle-Substrate n-Channel IGBT in 4H-SiC

The silicon carbide (SiC) waffle-substrate n-channel insulated gate bipolar transistor (IGBT) is a vertical IGBT designed to operate at blocking voltages below about 15 kV. At these voltages, the drift and anode layers are too thin to allow complete removal of the n + substrate. Instead, a waffle pattern is etched through the substrate to expose the buried anode layer while preserving the structural integrity of the wafer. The feasibility of this approach is demonstrated by fabricating a 10-kV class n-channel IGBT with a differential specific ON-resistance of 160 m Ω cm 2.