The High-k Metal Gate (HKMG) film stack, introduced since 32 nm node of complementary metal oxide semiconductor (CMOS) technology, is one major case where composition determination is mandatory. Parallel Angle-Resolved X-ray Photoelectron Spectroscopy (pARXPS) allows to perform high resolution chemical depth profiling characterization of advanced transistor technology gate stack. By applying the maximum entropy concept to the pARXPS measurements, it is possible to obtain depth profiling information. Although, the capability of this technique has been widely discussed in the past few years, we propose here to validate the pARXPS depth profiling technique using Medium Energy Ion Scattering (MEIS), another high resolution chemical depth profiling characterization technique. Comparison between pARXPS and MEIS measurements allowed us to validate the pARXPS depth profiling technique and to determine with accuracy the composition of HKMG HfON/SiON stack from the 14 nm node technology.