Stabilization of Nb/Si nano-multilayers by B4C diffusion barriers

Nb/Si multilayers which can be used in the extreme ultraviolet wavelength range were deposited by the magnetron sputtering method. In order to improve the thermal stability of the multilayer, B4C barrier layer was inserted into the interface between Nb and Si. The interface structures and crystallizations of Nb/Si multilayers with and without B4C barriers were investigated by grazing incidence X-ray reflection (GIXRR) and X-ray diffraction (XRD). The results show that the interface structures of Nb/B4C/Si/B4C multilayers are preserved well and no extra crystallization occurs after annealing at 500 degrees C for one hour. The period thickness varies by only 6% at 500 degrees C. In contrast, the interface structures of Nb/Si multilayers are destroyed rapidly and new compounds are formed when the annealing temperature reaches 500 degrees C and above. It can be verified that the introduction of B4C barrier layers improves the thermal stability of Nb/Si multilayer up to 500 degrees C.

Automated summary

The study showed that Nb/B4C/Si/B4C multilayers maintain good interface structures and minimal additional crystallization after annealing, while the interface structures of Nb/Si multilayers rapidly degrade and new compounds form at high temperatures. The introduction of B4C barrier layers significantly improves the thermal stability of Nb/Si multilayers.