In this study, Cu(In_1−xGa_x)Se₂ (CIGS) thin film was deposited on molybdenum (Mo) coated glass substrate by thermal co-evaporation technique and depth profile crystal orientation of the this film was examined by grazing incidence X-ray diffraction (GIXRD) method. The crystal structure of the CIGS thin film was determined within 20° to 80° (2θ) scanning range at 0.5° to 15° incidence angle of X-ray. Cross section images were investigated by scanning electron microscope measurements and these measurements showed that bilayer Mo thickness and CIGS thickness are approximately 480 nm and 2 µm, respectively. The surface roughness of films investigated by atomic force microscopy (AFM) and average roughness R_a was found 11.07 nm. According to GIXRD measurements; the interdiffusion of the constituent elements and their effect on the crystal structure were defined both electromagnetic field penetration (skin depth) and mass attenuation viewpoints, and also these results were supported by energy dispersive spectroscopy measurements. As a result, it was seen that the GIXRD method can be used with ease to define the crystal phase homogeneity and depth profile characterization of thin film volume applying skin depth theory.