This paper constitutes a continuation of studies on modification technologies for 7075 series aluminum alloys (Al-Zn) in plasmochemical conditions using the RF CVD (Radio-Frequency Chemical Vapor Deposition) method. This technique is simultaneously the second stage of alloy ageing. The presented results concern optimization of alloy surface modification using N+ ions (in NH3 or NH3/Ar atmosphere) before obtaining a DLC (Diamond-Like Carbon) layer doped with Si and N. From the results it can be concluded that the most profitable mechanical properties (H, ca. 12 GPa and E, ca. 115 GPa) are obtained when the SiCNH coating process is preceded by Al-Zn alloy surface modification with nitrogen ions. These ions are provided by a flowing NH3 and Ar gas mixture (1:1 ratio). In these process conditions, the lowest tribological wear of the surface is also observed. Furthermore, the obtained coating exhibits a fine-grained structure. (C) 2016 Elsevier B.V. All rights reserved.