Silicon (Si) and yttrium (Y) are believed to have a strong influence on functional properties of oxynitrides due to their effects in the growth process and incorporation in solid solution phases. It is worthwhile noting that the presence of these elements is strongly active for controlling structural evolution during the growth. The aim of this work is to systematically study the microstructural development and mechanical properties of (Al,Cr,Si/Y)OxN1 (-) (x) oxynitride films as a function of Si and Y contents. Our results show that Si and Y have a different mechanism for incorporation into the oxynitride films. According to the TEM, XRD, and XPS results a substitutional role of yttrium is suggested for the investigated coatings, whereas silicon tends to form an amorphous glassy phase. Such oxynitride layers with cubic structure (fcc-B1) meet an enhanced structural stability by the incorporation of both silicon and yttrium. As a result, the nitride growth regime is extended in the range of O/(O + N) <= 0.80. On the other hand, they hinder the formation of corundum phase in the predominant oxide regime (O/(O + N) >= 0.98) suggesting retarded diffusional processes with the presence of such alloying elements (i.e. Si and Y) in the deposition flux. Additionally, the Y-containing oxynitrides demonstrate a greater nano-hardness for all growth regimes. (C) 2013 Elsevier B.V. All rights reserved.