Growth and properties of amorphous Ti-B-Si-N thin films deposited by hybrid HIPIMS/DC-magnetron co-sputtering from TiB2 and Si targets

Amorphous nitrides are explored for their homogeneous structure and potential use as wear-resistant coatings, beyond their much studied nano- and microcrystalline counterparts. (TiB2)1-xSixN thin films were deposited on Si(001) substrates by a hybrid technique of high power impulse magnetron sputtering (HIPIMS) combined with dc magnetron sputtering (DCMS) using TiB2 and Si targets in a N2/Ar atmosphere. By varying the sputtering dc power to the Si target from 200 to 2000 W while keeping the average power to the TiB2-target, operated in HIPIMS mode, constant at 4000 W, the Si content in the films increased gradually from x = 0.01 to x = 0.43. The influence of the Si content on the microstructure, phase constituents, and mechanical properties was systematically investigated. The results show that the microstructure of as-deposited (TiB2)1-xSixN films changes from nanocrystalline with 2-4 nm TiN grains for x = 0.01 to fully electron diffraction amorphous for x = 0.22. With increasing Si content, the hardness of the films increases from 8.5 GPa with x = 0.01 to 17.2 GPa with x = 0.43.