Epitaxial Growth And Characterization Of Thick Multi-Layer 4h-Sic For Very High-Voltage Insulated Gate Bipolar Transistors

Techniques to fabricate thick multi-layer 4H-SiC epitaxial wafers were studied for very highvoltage p(-) and n-channel insulated gate bipolar transistors (IGBTs). Multi-layer epitaxial growth; including a thick p(-) drift layer (similar to 180 pm); was performed on a 4H-SiC n substrate to form a p-IGBT structure. For an n-IGBT structure; an inverted growth process was employed, in which a thick n- drift layer (similar to 180 pm) and a thick p injector layer (>55 Pm) were epitaxially grown. The epitaxial growth conditions were modified to attain a low defect density, a low doping concentration; and a long carrier lifetime in the drift layers. Reduction of the forward voltage drop was attempted by using carrier lifetime enhancement processes, specifically; carbon ion implantation/annealing and thermal oxidation/annealing or hydrogen annealing. Simple PiN diodes were fabricated to demonstrate the effective conductivity modulation in the thick drift layers. The forward voltage drops of the PiN diodes with the p(-) and n-IGBT structures promise to obtain the extremely low-loss and very high-voltage IGBTs. The change in wafer shape during the processing of the very thick multi-layer 4H-SiC is also discussed. 2015 AIP Publishing LLC.