SILICON-CARBIDE SHIELDED-MOSFET EMBEDDED WITH TRENCH SCHOTTKY DIODE AND HETEROJUNCTION GATE

摘要

A shielded Schottky heterojunction power transistor is made from a Silicon-Carbide (SiC) wafer with SiC epitaxial layers including a N+ source and a Silicon N-epitaxial layer under the gate with higher channel mobility than SiC. The bulk of the wafer is a N+ SiC drain contacted by backside metal. A trench is formed between heterojunction transistors. Metal contacting the N+ source is extended into the trench to form a Schottky diode with the N-SiC substrate. P+ taps on the sides of the trench connect the metal to a P-SiC body diode under the heterojunction gate, and also prevent the Schottky metal from directly contacting the P body diode. Buried P pillars with P+ pillar caps are formed under the trench Schottky diode and under the heterojunction transistors. The P pillars provide shielding by balancing charge with the N substrate, acting as dielectrics to reduce the E-field above the pillars.