Structure and Mechanical Properties of AlCrN Thin Films Deposited by Magnetron Sputtering

Abstract

A magnetron sputtering system was used to deposit AlCrN thin films. Chemical compositions of the films were determined by both EDXS and RBS, while structures analyses were conducted by XRD in a Seifert XRD3000 diffractometer. Macroscopic residual stresses of films were determined by curvature measurements using DEKTAK IIA profilometer, while in-grain stresses were extracted by the “sin²Y method” from XRD measurements. A nanoindenter from CSM (Switzerland) was used to determine the hardness of the films. A CrN type FCC structure was obtained with a strong (200) fiber texture for the range of compositions Al1-xCrxNy(0.56 < x< 0.89) of interest here. The global stresses were compressive for all FCC films resulting from the high energetic deposition conditions used. In-grain compressive stresses were determined for the films with thickness < 500nm, while thicker films (> 500nm) showed tensile in-grain stresses. Stress-free lattice parameter a0strongly decreased from 4.13 to 3.97 A°. Hardness values were obtained in a range extending from 17 to 27 GPa with an increase obtained as Cr content increases and correlated to the residual-stress level.