Influence of magnetron sputtering process parameters on the morphology of palladium thin films: An empirical study

Abstract The heightened initial energy of deposited atoms during the magnetron sputtering process alters the conventional rules of structure zone transformation for film morphology, posing challenges in fabricating Pd films with specific morphologies. This study aims to elucidate the impacts of substrate temperature and sputtering power on the morphology of Pd films and to determine the magnetron sputtering process parameters for preparing Pd films within a typical structure zone. Pd thin films were fabricated by using magnetron sputtering under varying substrate temperatures and sputtering powers. The morphologies of the films were examined through Scanning Electron Microscopy (SEM) and X-ray Diffraction (XRD). With increasing substrate temperature, the structure zone of Pd films transitions from Zone T to Zone 2, and subsequently to Zone 3. Given that initial energy enhances the diffusion capability of deposited atoms, the threshold temperature for structural zone transformation of Pd films prepared by magnetron sputtering is lower than the critical value suggested by the Structure Zone Model (SZM). While sputtering power does not critically affect the structure zone of Pd films, it influences grain size and preferred orientation. The substrate temperature is the decisive factor affecting the structural zone of thin films, with the critical temperature for structure zone transformation in magnetron sputtering being lower than that proposed by the Structural Zone Model (SZM). Furthermore, the research has determined the magnetron sputtering process parameters necessary for fabricating Pd thin films with specific structure zones. This study paves the way for subsequent enhancements in the hydrogen sensitivity of palladium thin film sensors through morphology control.