Growth and characterization of nitrogen-phosphorus hybrid passivated gate oxide film on N-type 4H-SiC epilayer

Abstract

A novel nitrogen-phosphorus (N&P) hybrid passivation technique by NO-containing dry oxidation of phosphorus-implanted 4H-SiC epilayer has been proposed to grow high-property gate oxide film. For demonstration and contrast, n-type 4H-SiC MOS capacitors with N&P hybrid and only N passivation have been fabricated and tested. The results from Secondary Ion Mass Spectroscopy (SIMS) reveal that about 60% of the implanted phosphorus atoms remain in the SiO2 film after sacrificial oxidation of the implantation layer. And the distribution of phosphorus is approximately uniform throughout the grown SiO2 film with a concentration about 4 × 1019 cm−3, avoiding the SiO2 film converting to phosphosilicate glass (PSG). I-V and X-ray Photoelectron Spectroscopy (XPS) data show that the grown SiO2 film with the appropriate phosphorus passivation can effectively improve the quality of oxide film, leading the gate oxide bandgap and integrity improved and reducing the leakage current above two orders of magnitude. The bias stress measurements with ultraviolet light (UVL) irradiation also show that the N&P hybrid passivation treatment can completely restrain the near-interface electron traps (NIETs) in 4H-SiC MOS devices, indicating that incorporation an appropriate amount of phosphorus atoms in the grown SiO2 film also can make the electron trap density reduced effectively.