Stable Ti/TaSi2/Pt Ohmic Contacts on N-Type 6H-SiC Epilayer at 600°C in Air

Abstract

ABSTRACTWe report preliminary electrical and diffusion barrier characteristics of Ti (100nm)/TaSi2 (200nm)/Pt (300nm) thermally stable ohmic contact metallization on n-type 6H-SiC epilayers. These contacts exhibited linear ohmic characteristics with contact resistance in the range of (0.3×10−4−8×10−4) Δcm2 on n-type epilayer doped between 0.6 to 2×1019cm−3. The I-V characteristics and contact resistance remained stable after heat treatments at 500°C and 600°C in air for over 600 hours and 150 hours, respectively. Auger Electron Spectroscopy (AES) was used to analyze the metal and semiconductor interfaces to understand the prevailing reactions. The thermal stability of the ohmic contact between 500°C and 600°C in air is believed to be due to the formation of silicides and carbides of titanium after being annealed at 600°C in H2 (5%)/N2 forming gas for 30 minutes. The oxidation of silicon species that migrated after TaSi2 decomposition is proposed as the diffusion barrier mechanism.