Evaluation of crack resistance of CrSiCN coatings as a function of Si concentration via nanoindentation

Abstract

A series of CrSiCN coatings with various Si concentrations were deposited on Si(100) wafers, and the influence of Si content on the microstructure, mechanical property and crack resistance of the coatings was investigated by XRD, Raman spectroscopy and nanoindentation. After introducing (CH3)3SiH into precursor from 5sccm to 30sccm, the Si concentration increased from 0.97at.% to 7.00at.% with gradually increasing formation of amorphous SiCx and SiNx. Under low Si concentration (0.97–3.40at.%) condition, solid solution effect and formation of nc-Cr(C,N)/a-SiNx(a-SiCx) architecture caused an increase in hardness from 18.1GPa to 21.3GPa. In contrast, at high Si concentration (5.35–7.00at.%), larger grain separation, which resulted from the increase of a-SiNx(a-SiCx), led to a drop of hardness to a low range of 13.0–13.6GPa and a decrease in compressive stress from 4.74GPa to 2.78GPa. As a result, superior elasticity and high compressive stress prevented the CrSiCN (Si<3.40at.%) coatings from radial crack, whereas the CrSiCN (Si≥3.40at.%) coatings confronted. However, after unloading, unbalance of high compressive stress (4.74 and 4.83GPa) in CrCN and CrSiCN (0.97at.%) coatings initiated cracks parallel to the indenter edge. On account of favorable H/E, H3/E2 and compressive stress, the CrSiCN coating with 2.05at.% Si presented the best mechanical property and crack resistance.