Time-of-flight secondary ion mass spectrometry has been used for depth profiling of 530 nm-thick Be/Al-based multilayer interferential structures fabricated by magnetron sputtering for X-ray radiation at the wavelength of 17.1-17.5 nm. The introduction of ultra-thin (< 1 nm) Si barrier layers inside each period of ca. 8.9 nm decreased the thickness of interfaces between layers, increased the modulation factor of sputter depth profiles for both main elements and the relative intensity of Al-2(+) /Be-2(+) secondary ions. For all structures with Si barriers, irrespective of the succession of the deposited layers, the improvement of the reflectance as compared with nobarrier Be/Al structure was revealed. Si/Al/Si/Be structure can be considered as the most prospective, but the realization of its potential requires further optimization of the width of Si barriers and the corresponding Si concentration in the multilayer structures.