Pressure influence on the depth resolution of rf-glow discharge depth profiling of multilayer coatings

Multilayer coatings (MLC) of known composition and thickness, 5x(100nm Al/1 00nm Ti), 10x(300nm CrN/300nm CrAlN)/100nm Cr and 30x(100nm CrN/100nm CrAlN )/100nm Cr, deposited onto steel substrates (SS) were analysed by depth pro filing using radiofrequency (rf)-glow discharge optical emission spectrosco py (GD-OES). The aim of the investigation was to find the optimal depth res olution by varying the rf-powered discharge guiding parameters. For the sam ples analysed here, the selected rf-discharge guiding parameters were the p eak-to-peak voltage and the argon flow rate. Optimal discharge conditions w ere obtained by applying a constant peak-to-peak voltage of 2000V as well a s low Ar flow rates [40-50 standard cubic centimetres per minute (sccm)], w here the relative depth resolution of the MLC/SS interface region improved significantly. A transient unstable rf-discharge pressure regime resulting in a worse depth resolution was also found.