Effects of the substrate to chamber wall distance on the structure and properties of CrAlN films deposited by pulsed-closed field unbalanced magnetron sputtering (P-CFUBMS)

The aim of the research was to determine the dependence of the structure and properties of CrAlN films deposited by pulsed closed field unbalanced magnetron sputtering (P-CFUBMS) on the substrate to chamber wall distance. A Hiden Electrostatic Quadrupole Plasma Analyser (EQP) has been used to investigate the positive ion energy distributions (IED) in the plasma. It was found that increasing the substrate to chamber wall distance from 127 mm to 203 mm can significantly increase the ion flux in front of the substrate. The improvement of the ion flux in front of the substrate region facilitates ion bombardment on the substrate, increases the mobility of the adatoms on the substrate surface, thereby resulting in a denser film with reduced grain size, which exhibited high hardness (∼ 30 GPa) and good wear resistance (0.35 COF, and a wear rate of 3.36 × 10− 6 mm3 N− 1 m− 1) at the substrate to chamber wall distance of 203 mm. The CrAlN film deposited at a relatively short substrate to chamber wall distance with the rotation system has comparable structure and properties with those films deposited at large substrate to chamber wall distance at fixed substrate positions.