Densification of silicon dioxide formed by plasma-enhanced atomic layer deposition on 4H-silicon carbide using argon post-deposition annealing

Post-deposition annealing (PDA) was used to improve gate oxide physical and electrical properties. Deposition was accomplished by plasma-enhanced atomic layer deposition (PEALD). We investigated the densification silicon dioxide (SiO2) formed by PEALD on 4H-silicon carbide (SiC) using PDA without oxidation and nitridation. PDA was conducted at 400-1200 °C in argon (Ar) ambient. The thickness of the SiO2 was reduced by up to 13.5% after Ar PDA at 1000 °C. As the temperature of the Ar PDA increased, the etching rate of SiO2 decreased. At temperatures greater than 1000 °C, the SiO2 etching rate was low compared with that of thermal SiO2. After PDA, the SiO2/4H-SiC interface was smoother than that of thermal SiO2/4H-SiC. The current density versus oxide field and capacitance versus voltage of the SiO2/4H-SiC metal oxide semiconductor (MOS) capacitors were measured. Sufficient densification of SiO2 formed by PEALD on 4H-SiC was obtained using Ar PDA at 1200 °C.