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 SiO 2 film after sacrificial oxidation of the implantation layer. And the distribution of phosphorus is approximately uniform throughout the grown SiO 2 film with a concentration about 4×10 19 cm-3 , avoiding the SiO 2 film converting to phosphosilicate glass (PSG). I-V and X-ray Photoelectron Spectroscopy (XPS) data show that the grown SiO 2 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 SiO 2 film also can make the electron trap density reduced effectively.

Analysis of the electronic and chemical structure in boron and phosphorus passivated 4H-SiC/SiO2 interfaces using HRTEM and STEM-EELS

“…In the case of phosphorus, secondary ion mass spectrometry (SIMS) has suggested the full conversion of SiO 2 into PSG, with a uniform concentration of P through the layer. 20,30 X-ray photoelectron spectroscopy (XPS) measurements have indicated a uniform atomic fraction for P of 5% within the PSG layer. 22 Using transmission electron microscopy (TEM), Fiorenza et al 31 reported a similar finding of P "almost homogeneously distributed within a) the insulating layer" as measured with energy dispersive X-ray spectroscopy (TEM-EDS).…”