Takehiko Mae

Influence of sputtering conditions on the structure and properties of Ti-Si-N thin films prepared by r.f.-reactive sputtering

Abstract The influence of Si content and sputtering conditions on the microstructure and mechanical properties (hardness and Youngs modulus) of Ti–Si–N were investigated using XRD, XPS and nano-indentation. The composite targets consisting of a Ti plate and Si or Si 3 N 4 chips were sputtered in a mixture of argon and nitrogen. Ti–Si–N films were prepared in an r.f. sputtering apparatus of the facing target-type. During the deposition, the substrate was heated from room temperature up to ∼573 K and a bias of d.c. up to −100 V was applied. Without substrate heating and bias, the hardness of the films increased from 30 GPa for a binary system, reaching a maximum of 37 GPa for a ternary system with a small amount (3–8 at.%) of Si. It then decreased to lower values than those of binary systems when Si was more than 10 at.%. The tendency to grow columnar grains was strongest at approximately 5 at.% of Si. The hardness of Ti–Si–N films increased and reached to a maximum value of 42 GPa around at a bias of −10 V, but the crystallite size of the film remained larger than 23 nm. The increase of hardness with small amounts of Si in TiSiN films was probably associated with the lattice distortion. On the other hand, the increment of hardness of films containing 20 at.% of Si by the negative bias application could be attributed to the formation of nano-composite structure.

Structure and properties of Cr–B, Cr–B–N and multilayer Cr–B/Cr–B–N thin films prepared by r.f.-sputtering

Abstract Cr–B, Cr–B–N and Cr–B/Cr–B–N multilayer films were synthesized by r.f. plasma-assisted magnetron sputtering using a CrB target (99.9% in purity) on silicon wafer substrates. The multilayer coatings were prepared by sequential sputtering using a nitrogen gas flow controller and a shutter by the sputtering of the CrB target. The films were deposited with an r.f. power of 120 W (target) and 100 W (coil) without substrate bias application, and the film thickness was controlled to ∼1 μm by adjusting the sputtering time. The micro-structure of thin films was studied by XRD and TEM and the chemical bonding state of films was investigated by XPS. The hardness and Youngs modulus of the films were studied in detail by the nano-indentation system. A ball-on-disk tribometer was used to measure the friction and wear behavior. A study of their microstructure and mechanical properties has provided the following results: XRD, TEM and XPS measurements revealed that the Cr–B films consist of CrB phase mainly and Cr–B–N films contain CrB and h-BN phase with an amount of unknown phases. The hardness for the films of Cr–B and Cr–B–N was 17 and 13 GPa, respectively. On the other hand, Cr–B/Cr–B–N multilayer films exhibited higher hardness reaching to 20 GPa regardless of the sublayer thickness. Cr–B and Cr–B–N films showed the Youngs modulus of 204 and 216 GPa, respectively. The Youngs modulus of Cr–B/Cr–B–N multilayer films increased to approximately 240 GPa regardless of the sublayer thickness as well. Furthermore, the friction coefficient of Cr–B/Cr–B-N multilayer exhibited an intermediate value of ∼0.45 between those of Cr–B (0.9) and Cr–B–N (0.2).