Morphological and structural characterization of magnetron-sputtered aluminum and aluminum-boron thin films

Abstract

In microelectronic mechanical systems applications, sputtered aluminum thin films may have large roughness, which promotes the optical degradation and electromigration. This challenge motivated the present research, where magnetron sputtering equipped by radio frequency allowed for preparing aluminum and aluminum-boron thin films. This study evaluated the effect of the sputtering power and the substrate type (silicon wafer and glass slides) on the deposited films. The film’s morphology and structure were characterized via an atomic force microscope and X-ray diffraction. Pure aluminum films’ topographic findings revealed a 25.23 nm average roughness with larger grain size and hillock formation. Conversely, the aluminum-boron films possessed a 3.41 nm average roughness, with smaller grains and hillocks suppression when higher sputtering power was used. The pure aluminum films’ structural analysis uncovered a material with low crystallinity, with (111) and (200) planes diffracting X-rays. On the other hand, aluminum-boron films displayed better crystallinity and a preferential (111) texture. Further characterization demonstrated how the sputtering power, the substrate material, and the studied targets affected the films’ morphological and structural. The improvements in morphological and structural aspects that were observed in the films that were obtained via the aluminum-boron target sputtering make this methodology an appealing alternative for metal films manufacturing.