Optical Emission Spectroscopy and Ultrafast Arc Management Strategy on the Quality of AlN Thin Films Using a 13.56 MHz RF Generator

This study focuses on the obtaining quality of arc-managed aluminum nitride (AlN) films in a PVD plasma system using a 13.56 MHz RF power source. Key parameters such as reflection coefficient (Г), suppression time, and re-ignition time were studied with the aim of reducing arc interference, increasing film crystallinity, and improving surface morphology. The key innovation of this work lies in the implementation of an ultrafast arc management strategy, with suppression/re-ignition times as short as 2 µs/2 µs—significantly shorter than those typically reported in the literature (50–1000 µs). This ultrashort modulation intercepts arc events at their micro-discharge stage, effectively minimizing energy accumulation and preventing the formation of high-energy "hard arcs." Consequently, this approach stabilizes plasma conditions and leads to significant improvements in film crystallinity, surface smoothness, and deposition rate uniformity, offering a new pathway toward high-performance AlN thin film fabrication in RF sputtering systems. In the plasma spectra obtained from in situ optical emission spectroscopy (OES), significantly higher spectral intensities were observed during radio frequency (RF) sputtering, particularly the emission feature associated with ionized nitrogen (N₂⁺) at approximately 390.93 nm. This suggests that RF plasma provides energy conditions favorable for the formation of high-quality aluminum nitride (AlN) films. Furthermore, we applied the principal component analysis (PCA) algorithm for big data analysis to reduce dimensionality and visualize the clustering patterns of OES data recorded during thin film deposition under three different suppression/re-ignition conditions: 2 µs/2 µs, 100 µs/50 µs, and 1000 µs/500 µs.