Mechanical properties of nanocomposite and multilayered Cr-Si-N sputtered thin films

We have investigated the structural and mechanical properties of polycrystalline Cr-Si-N thin films of different morphologies. The films were deposited by reactive magnetron sputtering at 510 K using two confocal targets of Cr and Si. The structure and mechanical properties of co-deposited Cr-Si-N films depend on their silicon content. Films with silicon content lower than 3 at.% are fcc Cr1-xSixN compounds with a maximum hardness of 22 GPa. On the contrary, films containing more than 3 at.% of silicon show the segregation of a SiNx amorphous phase and highly columnar morphology. These samples have low hardness values (14 GPa). The alternating deposition of CrN and a-SiNx layers disrupts this columnar structure and leads to nanocomposite films. The hardness of these films varies when the multilayer period is changed, i.e. the CrN crystallite size. A maximum hardness value (26 GPa) has been found for a nanocomposite structure composed of 4 nm CrN crystallites embedded in amorphous SiNx. (C) 2003 Elsevier B.V. All rights reserved.