Design of SiO2/4H–SiC MOS interfaces by sputter deposition of SiO2 followed by high-temperature CO2-post deposition annealing

Abstract

Oxidation of silicon carbide (SiC) is known to induce defects at the interface of the SiO2/SiC system. NO-annealing is a standard industrial method of nitridation, but oxidation may progress during NO-nitridation, which may generate interface defects. Here, we propose a new method of fabricating SiO2/SiC metal-oxide-semiconductor (MOS) devices: sputter deposition of SiO2 in an Ar/N2 gas mixture followed by high-temperature CO2-post deposition annealing to form SiO2 and incorporate nitrogen at the interface while suppressing oxidation of the SiC. We obtained the nitrogen depth profile by performing x-ray photoelectron spectroscopy and confirmed that most of the nitrogen atoms exist at the abrupt interface. While maintaining a low interface state density and good insulating property, we demonstrated much improved reliability of MOS devices compared to conventional NO-annealed samples, thanks to the well-designed SiO2/SiC interface by the proposed method.

4H-SiC/SiO2 Interface Degradation in 1.2 kV 4H-SiC MOSFETs Due to Power Cycling Tests

“…Failure modes in gate oxide include threshold voltage shifts and increased leakage currents [8]. High interface trap density is mentioned as the primary cause of these phenomena [8][9][10][11]. Therefore, there was a variety of research performed to overcome the reliability issue at the 4H-SiC/SiO 2 interface.…”

“…Additionally, the paper explores advanced techniques such as nitrogen implantation and wet oxidation processes to passivate near-interface traps and improve the overall electrical quality of the 4H-SiC/SiO 2 interface [12]. These strategies aim to mitigate interface-related challenges and enhance the performance and reliability of 4H-SiC power MOSFETs by addressing critical issues at the SiC/SiO 2 interface [10]. On the other hand, degradation owing to the 4H-SiC/SiO 2 interface becomes more pronounced while the device is operating [7,9].…”