NO Plasma Treatment Effects on the Structural and Electrical Properties of PECVD-Grown SiO2 Films

As device scaling processes, widely used silicon dioxide (SiO₂) films in semiconductor devices face increasing challenges from interfacial defects, oxygen vacancies, and suboxide states that degrade their dielectric performance. Therefore, an effective post-treatment method is critical for enhancing their stability, reproducibility, and reliability. In this study, SiO₂ films deposited via plasma-enhanced chemical vapor deposition (PECVD) were treated with nitric oxide (NO) plasma for durations of 0, 1, 4, and 10 min to evaluate its impact on their electrical and chemical structural properties. The results revealed significant improvements in the dielectric performance with the leakage current density decreasing from 9 × 10^-9 to 1.2 × 10^-10 A cm^-2 and the breakdown electric field increasing from 6.79 to over 15 MV cm^-1 after 10 min of treatment. Capacitance-voltage (C-V) measurements showed a rightward shift and a steeper slope, indicating reduced fixed charges and an interface trap density (D_it), which decreased nearly 10-fold from 7.4 × 10¹² to 7.17 × 10¹¹ cm^-2 eV^-1. X-ray photoelectron spectroscopy (XPS) analysis confirmed reductions in suboxide states of Si (Si⁰, Si⁺, Si²⁺, and Si³⁺) and the replacement of Si-N bonds with stable Si-O bonds. Furthermore, atomic force microscopy (AFM) measurements showed a reduction of surface roughness from 0.86 to 0.56 nm, indicating an improvement of surface morphology. These improvements contribute to the enhanced stability and reliability of the SiO₂ films, making NO plasma treatment a promising approach for achieving an enhanced dielectric performance in next-generation semiconductor devices.