Improvement of the electrical properties of PECVD silicon oxide using high-density and low-ion-energy plasma post-treatment

We have studied the electrical properties of the high-quality plasma enhanced chemical vapor deposition (PECVD) silicon oxide deposited by high-density and low-ion-energy plasma at 400 °C and the effect of the plasma post-treatment on its electrical properties. Analysis of the gate voltage shift during constant current stress and the high-frequency C-V characteristics indicate that the bulk electron trap and the interface charge densities are reduced from 3.2 ± 0.1 × 10¹⁸ cm^-3 and 1.5 ± 0.1 × 10¹¹ cm^-2 to 1.5 ± 0.2 × 10¹⁸ cm^-3 and 4 ± 0.3 × 10¹⁰ cm^-2 by the high-density and low-ion-energy plasma post-treatment, respectively. In addition, the capture cross-section of the bulk trap is 2.6 ± 0.2 × 10^-18 cm². The silicon oxide films deposited by the high-density low-ion-energy plasma and plasma post-treatment exhibit excellent properties, e.g., high-breakdown electric field (>12 MV/cm) and high charge-to-breakdown. These properties of the films have approached those of high-temperature thermal oxide films.