This study presents a stacked process of thermal and atomic layer deposition (ALD) SiO2 that reduces the interface trap density of 4H-SiC metal-oxide-semiconductor (MOS) capacitors. The channel mobility of metal-oxide-semiconductor field effect transistors are reduced due to the high interface trap density as well as coulomb scattering mechanism. Herein, we investigate SiO2/SiC interface properties of a stacked process, which is accomplished via reducing the thickness of thermal oxidation film. Notably, MOS capacitors fabricated with thermal and ALD SiO2 stacked structures can reduce the interface state density (Dit) by twofold at 0.2 eV below the conduction band energy compared with thermally grown SiO2. Furthermore, the interface state density decreases more steeply in the range of energy levels close to the conduction band. Additionally, the leakage current increases at a relatively slow rate in the electric field of 5 -10 MV/cm, whereas the leakage current increases sharply when the electric field is higher than 10 MV/cm. The resultant ALD SiO2 stacked structure provides a new approach to improving interface quality, which allows for a reduction in the thermal budget involved in the fabrication and preparation of devices.

Detailed investigations of the pre-oxidation phosphorus implantation process are required to increase the oxidation rate in 4H-SiC metal-oxide-semiconductor (MOS) capacitors. This study focuses on the SiO2/SiC interface characteristics of pre-oxidation using phosphorus implantation methods. The inversion channel mobility of a metal-oxide-semiconductor field effect transistor (MOSFET) was decreased via a high interface state density and the coulomb-scattering mechanisms of the carriers. High-resolution transmission electron microscopy (HRTEM) and scanning transmission electron microscopy (STEM) were used to evaluate the SiO2/SiC interface’s morphology. According to the energy-dispersive X-ray spectrometry (EDS) results, it was found that phosphorus implantation reduced the accumulation of carbon at the SiO2/SiC interface. Moreover, phosphorus distributed on the SiO2/SiC interface exhibited a Gaussian profile, and the nitrogen concentration at the SiO2/SiC interface may be correlated with the content of phosphorus. This research presents a new approach for increasing the oxidation rate of SiC and reducing the interface state density.